Zongsoft.Data 7.29.0

Zongsoft.Data ORM Framework

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<a name="abstract"></a>

Abstract

The Zongsoft.Data is a GraphQL-style ORM(Object/Relational Mapping) data access framework.

Its core idea is simple: describe the data shape and entity relationships declaratively, and let the engine generate the SQL. Most application code can query, write, and navigate data without hand-written SQL or SQL-like strings.

<a name="feature"></a>

Features

• Supports strict POCO objects without attribute or annotation dependencies;
• Supports read/write splitting;
• Supports data operations on inherited tables;
• Keeps mappings isolated by business module and provides extension points;
• Supports navigation, filtering, paging, grouping, and aggregation without hand-written SQL;
• Fits common object-oriented programming habits and is easy to start with;
• Focuses on balanced performance, maintainability, and ease of use;
• Keeps dependencies small, usually only ADO.NET plus the native ADO.NET driver.

<a name="driver"></a>

Drivers

Driver	Project Path	State
MySQL	/drivers/mysql	Available
SQL Server	/drivers/mssql	Available
PostgreSQL	/drivers/postgres	Available
SQLite	/drivers/sqlite	Available
DuckDB	/drivers/duckdb	Available
ClickHouse	/drivers/clickhouse	Available
InfluxDB	/drivers/influx	Available
TDengine	/drivers/tdengine	Available

💡 Tip: If you need a driver that is not listed here or commercial support, please contact us (zongsoft@qq.com).

<a name="plugin-quickstart"></a>

A Real Plugin Workflow: Discussions

The Discussions module obtains its accessor through the Core contract IDataAccessProvider. The module name is Discussions; its mapping uses the same container name. The engine and driver are composed by the host, not constructed by each business service.

1. Deploy the Module, Engine, and Driver

Add the following packages to an existing host deployment manifest; retain its Main, Web/Terminal and Security dependencies. See plugin composition.

[plugins zongsoft data]
nuget:Zongsoft.Data

[plugins zongsoft data mysql]
nuget:Zongsoft.Data.MySql

[plugins zongsoft discussions]
nuget:Zongsoft.Discussions

2. Prepare the Actual Data and Configuration

Follow the Discussions database documentation and module deployment manifest. Deploy the complete mapping and plugin, including validators and filters. Configure a named Discussions connection under /Data/ConnectionSettings, and configure the site and file storage using the module option file. Mapping files describe existing structures; loading one does not initialize a database.

3. Locate the Accessor from the Module

This is the accessor property from Module.cs, not a standalone program:

private IDataAccess _accessor;
public IDataAccess Accessor => _accessor ??=
	this.Services.ResolveRequired<IDataAccessProvider>().GetAccessor(this.Name);

ForumService and ThreadService inherit DataServiceBase<T> and operate through this.DataAccess. Read their methods together with DataValidator, which supplies the module's data boundary.

🚨 This is a source walkthrough, not a claim that a fresh Discussions deployment has passed integration testing. Use an isolated database with initialized site/user data and the appropriate identity. Do not bypass validators to make an example run, or dispose a container-owned accessor after each request.

<a name="schema"></a>

The data schema

The data schema is a DSL(Domain Specific Language) that describes which fields are queried or written (Delete/Insert/Update/Upsert). It looks similar to GraphQL, but it does not need a server-side GraphQL definition. It is used to choose fields, include navigation properties, and control cascade scopes.

The schema argument in a data access method is the schema text.

<a name="schema-syntax"></a>

Schema Syntax

schema ::=
{
    * |
    ! |
    exclusion |
    inclusion
} [,...n]

identifier ::= [_A-Za-z][_A-Za-z0-9]*
number ::= [0-9]+

path ::= identifier {"." identifier}
exclusion ::= "!" path
inclusion ::= path [limit] [sorting] ["{" schema [,...n] "}"] | path ".*"

limit ::= ":"(number | "*")

sorting ::=
"("
    {
        ["~"|"-"|"+"]identifier
    } [,...n]
")"

💡 The Department.Manager / Secret grammar examples below come from the actual SchemaParserTest fixture and Core SchemaTest. They test parsing, not a Discussions organization module.

<a name="schema-overview"></a>

Schema Overview

• Asterisk(*): includes all scalar properties. Navigation properties are not included unless you name them explicitly.
• Exclamation(!): excludes fields. A bare ! clears all members at the current level; !Name excludes the named property.
• A dot(.) joins nested member names. Department.Manager.Name is equivalent to Department{Manager{Name}}, and dotted paths may be mixed with braces. Whitespace is allowed on both sides of a dot.
• A terminal mapped navigation property automatically includes its scalar properties. Therefore Department, Department.*, and Department{*} produce the same member tree. The .* form is terminal and cannot be followed by another path segment.
• A dotted exclusion such as !Department.Manager.Secret validates every segment and removes only the target member. !Department removes the whole navigation member and is equivalent to Department{!}. The !* form and !path.* are invalid.
• Identifiers are composed of letters, digits, and underscores, must not start with a digit, and are case-insensitive.
• Multiple members are separated by commas(,); the sub-schema （inside the braces） uses the same syntax, so nesting is allowed at any depth. Empty comma segments and leading/trailing commas are ignored.
• Whitespace is not allowed inside an identifier, but is allowed between members, after the asterisk, and between an identifier and the sub-schema/sorting/limit tokens, e.g. Users {*}、Users :20、* , Users.
• Whitespace is not allowed inside a limit or right after the colon(:); it is not allowed inside the sorting parentheses or a sorting field, but is allowed between sorting fields （after a comma）.
• A limit or sorting expression finishes the dotted path. For example, Departments:10(~Name) includes the navigation's scalar properties, while Departments:10.Manager and Departments:10(~Name).Manager are invalid.

<a name="schema-paging"></a>

Limit and Sorting

A limit is written after the member name and starts with a colon(:). It controls the maximum number of records loaded for a one-to-many member:

Syntax	Meaning
omitted	unlimited （the default）
:N	at most N records when N > 0
:0	unlimited
:*	unlimited

The parsed limit is an integer. Any value less than or equal to zero means unlimited; canonical schema text omits an unlimited limit. Schema expressions accept only unsigned numbers or * after the colon.

Sorting is written after the optional limit and wrapped in parentheses; sorting fields are separated by commas. A ~ or - prefix means descending, while a + prefix or no prefix means ascending:

Users:20(-IsModerator,+UserId){*}

Every sorting field may carry its own prefix. +CreatedTime is exactly equivalent to CreatedTime. If a field is declared more than once, the last declaration determines its direction and position.

<a name="schema-sample"></a>

Sample description

• Note: All scalar properties except CreatorId and CreatedTime.

  *, !CreatorId, !CreatedTime
  

• Note: All scalar properties plus the Creator navigation property, including all scalar properties of Creator.

  *, Creator{*}
  

  The following forms are equivalent:

  *, Creator
  *, Creator.*
  *, Creator{*}
  

• Note: All scalar properties plus the Creator navigation property, but only Name and Nickname are loaded for Creator.

  *, Creator{Name,Nickname}
  

• Note: All scalar properties plus the Users collection navigation property (one-to-many), without sorting or a record limit.

  *, Users{*}
  

• Note: All scalar properties plus the Users collection navigation property (one-to-many), limited to at most 1 record.

  *, Users:1{*}
  

• Note: All scalar properties plus the Users collection navigation property (one-to-many), limited to at most 20 records.

  *, Users:20{*}
  

• Note: All scalar properties plus the Users collection navigation property (one-to-many) with an explicitly unlimited record count.

  *, Users:*{*}
  

• Note: All scalar properties plus the Users collection navigation property (one-to-many), sorted by IsModerator descending and UserId ascending, then limited to at most 20 records.

  *, Users:20(-IsModerator,+UserId){*}
  

---

💡 Nested braces can be replaced or mixed with dotted paths. The following expressions produce the same member tree:

*, User,
Department.*,
Department.Manager.Name,
Department.Manager.Gender,
Department.Manager.FullName,
!Department.Manager.Secret

*, User{*}, Department{*, Manager{Name,Gender,FullName,!Secret}}

<a name="schema-computed"></a>

Computed Members

An explicitly named member that is not mapped may still be used when the corresponding model defines a public instance property or field with that name. Such a computed member participates in the returned model shape but does not generate a database field. An unknown name that exists in neither the mapping nor the model is invalid. The * wildcard includes mapped scalar properties only and never adds computed members automatically.

💡 Note: Any mapped inputs required by a computed property must be included explicitly.

<a name="mapping"></a>

Mapping file

A data mapping file is an XML file with the .mapping extension. It defines the metadata for entities, tables, fields, keys, and navigation relationships. Do not put all metadata for a large application into one file; each business module should have its own mapping file.

The Zongsoft.Data.xsd XML Schema file provides IntelliSense and validation for hand-written mapping files.

The mapping file root is schema, and each container represents one metadata namespace. Most business modules have one container whose name matches the module name.

The following is a partial excerpt of the Discussions mapping; deploy the original complete file, not this shortened fragment.

<schema xmlns="http://schemas.zongsoft.com/data">
	<container name="Discussions">
		<entity name="Forum" table="Discussions_Forum">
			<key>
				<member name="SiteId" />
				<member name="ForumId" />
			</key>
			<property name="SiteId" type="uint" nullable="false" />
			<property name="ForumId" type="ushort" nullable="false" sequence="#(SiteId)" />
			<property name="GroupId" type="ushort" nullable="false" />
			<property name="Name" type="nvarchar" length="50" nullable="false" />
			<complexProperty name="Users" port="ForumUser" multiplicity="*" immutable="false">
				<link port="SiteId" />
				<link port="ForumId" />
			</complexProperty>
		</entity>
	</container>
</schema>

Common mapping elements:

• entity maps an application entity to a table. table is the physical table name（when omitted it defaults to namespace_entity, or the entity name when the namespace is empty; alias is also accepted as an alternative to table）, inherits points to a parent entity, driver limits the entity to a specific data driver, and immutable="true" makes the entity read-only except for insert operations.
• property maps a scalar member to a field. Important attributes include type, field, nullable, length, precision, scale, default, sequence, sortable, and immutable.
• sequence="*" means the database built-in identity/sequence is used. sequence="#" means the Zongsoft default external sequencer is used. sequence="#Name" means a named external sequencer; sequence="#Name@seed/interval" also specifies the seed and interval; sequence="#(ParentId)" means an external sequencer grouped by the specified reference property; sequence="Entity:Property" references the sequencer of another entity's property.
• complexProperty defines a navigation property. Its port points to the target entity, or to a target entity's navigation property such as ForumUser:User. multiplicity supports ?（zero-or-one，default）、!（exactly one）、*（one-to-many）; link maps foreign key properties to the current entity（anchor specifies the anchor on the current side and defaults to the port name when omitted）, and constraints add fixed navigation filters（when actor is omitted it is inferred from the multiplicity: Foreign for one-to-many, otherwise Principal）.
• command defines a named SQL command or stored procedure. Commands are executed through Execute, Execute<T>, or ExecuteScalar. type supports text（default）and procedure; mutability declares whether the command reads or writes data. It is not merely descriptive metadata: when read/write splitting is configured, the data source selector uses it as the routing basis—none selects a readable source, while delete、insert、update、upsert select a writable source. The selector does not infer mutability by analyzing the SQL text. The loader parses these enum values case-insensitively, but use lowercase to pass XSD validation.

The current Discussions mapping does not define a forum statistics command or stored procedure. For the command contract, refer to MetadataCommand and the XSD; do not call a name that has not been deployed.

Enable XML IntelliSense for mapping files:

Copy Zongsoft.Data.xsd and Zongsoft.Data.catalog.xml to the XML Schemas template directory of Visual Studio, for example:

• Visual Studio 2026 (Enterprise Edition) <br /> C:\Program Files\Microsoft Visual Studio\18\Enterprise\Xml\Schemas

Although some developers like generating mapping files, we recommend writing them by hand:

• Data structures and relationships are the foundation of a system. Database tables are their physical form, and mapping files describe how application entities match those tables.
• Mapping files should be maintained by the system architect or module owner. Settings such as inherits, immutable, sortable, sequence, and navigation properties directly affect application code.

<a name="connection"></a>

Connection Settings

The connection name is resolved by DataAccessProviderBase. Discussions requests its module name; configure that name explicitly instead of accidentally falling back to another module's default connection.

Use the following configuration shape with deployment-supplied values. REPLACE_WITH_* marks required environment values, not a shipped account or database.

<options>
	<option path="/Data">
		<connectionSettings>
			<connectionSetting connectionSetting.name="Discussions" driver="MySql"
				value="Server=REPLACE_WITH_HOST;Database=REPLACE_WITH_DATABASE;UserName=REPLACE_WITH_USER;Password=REPLACE_WITH_PASSWORD" />
		</connectionSettings>
	</option>
</options>

For read/write separation, use accessor#source names and ReadOnly/WriteOnly modes. This is an engine capability, not a claim that Discussions ships a replicated database topology. See DataSourceSelector and the MySQL driver. Replication, consistency and credentials remain deployment responsibilities.

<a name="usage"></a>

Usages

All data operations go through the Zongsoft.Data.IDataAccess interface in Zongsoft.Core. It supports these operations:

• int Count(...)
• TValue? Aggregate(...)
• bool Exists(...)
• IEnumerable<T> Execute<T>(...) object ExecuteScalar(...)
• int Import(...)
• int Delete(...)
• int Insert(...) int InsertMany(...)
• int Update(...) int UpdateMany(...)
• int Upsert(...) int UpsertMany(...)
• IEnumerable<T> Select<T>(...)

💡 Examples use the real Discussions models and mapping. Code explicitly marked as an excerpt comes from the linked service. Other queries are local API adaptations against those models, not additional deployed services. They run inside a module service after plugin composition; siteId and userId denote validated caller identity values, not user-supplied authorization overrides. See the database design before trying writes.

<a name="operand"></a>

Operand

Operands can be used in conditions (Condition) and in values written to fields. The main operand types are:

• Constant operand ConstantOperand<T>
• Field operand FieldOperand
• Function operand FunctionOperand
• Aggregation operand AggregateOperand
• Unary operand UnaryOperand, including:

• ! logical NOT
• ~ bitwise NOT
• - arithmetic negation

• Binary operand BinaryOperand, including:

• + addition
• - subtraction
• * multiplication
• / division
• % remainder
• & bitwise or logical AND
• | bitwise or logical OR
• ^ bitwise or logical XOR

Examples

ThreadService.OnGet increments the persisted view count after its access checks. The following is its update fragment:

this.DataAccess.Update<Thread>(new
{
	TotalViews = Operand.Field(nameof(Thread.TotalViews)) + 1,
	ViewedTime = DateTime.Now,
}, Condition.Equal(nameof(Thread.ThreadId), thread.ThreadId));

Operand.Field refers to the stored value; + 1 is evaluated by the database rather than by a client-side read/modify/write loop. Keep the surrounding authorization and history handling when reading this service.

For operator precedence without a database, OperandTest.Test1 constructs the expression below and checks its tree. These constants are test inputs, not an order-processing application:

Operand a = Operand.Constant(1);
Operand b = Operand.Constant(2);
Operand c = Operand.Constant(3);
Operand d = Operand.Constant(4);
Operand e = Operand.Constant(5);

var expression = (a + b) * (c - d) / e;

Function and aggregate operands are defined by Operand; database support depends on the selected driver.

<a name="condition"></a>

Condition

Condition represents predicates for queries and writes. Combine conditions with & and |; keep authorization constraints outside any business OR group.

The actual ForumService.GetThreads starts with:

var criteria =
	Condition.Equal(nameof(Thread.ForumId), forumId) &
	Condition.Equal(nameof(Thread.Visible), true);

The method then excludes the separately loaded topmost threads on the first page before calling Select<Thread>. See the complete method for paging behavior.

Search DTOs are also real models: ThreadCriteria in Thread.cs declares nullable fields and a Range<DateTime>? time range; its Title property uses [Condition(ConditionOperator.Like)]. ThreadService selects that type with [DataService(typeof(ThreadCriteria))]. Do not redefine a different DTO with the same name. The Core Criteria API supplies parsing and transformation.

<a name="usage-query"></a>

Query operation

<a name="usage-query-1"></a>

Basic query

• By default, all scalar fields are returned. Use the schema argument to choose a smaller field set.
• Query results are lazy. Actual data access starts when you enumerate the result or call LINQ methods such as ToList() or First().

Note: Queries are not paged by default. Avoid calling ToList() or ToArray() on a large result set unless you really need all rows in memory.

// Query all scalar fields that match the condition(lazy loading).
var threads = this.DataAccess.Select<Thread>(
	Condition.Equal("SiteId", siteId) &
	Condition.Equal("Visible", true));

// Query one entity and load only selected fields.
var forum = this.DataAccess.Select<Forum>(
	Condition.Equal("SiteId", siteId) &
	Condition.Equal("ForumId", 100),
	"SiteId,ForumId,Name,Description,CoverPicturePath").FirstOrDefault();

<a name="usage-query-exists"></a>

Exists and aggregate query

Use Exists when you only need to know whether a row exists. Use Count, Sum, Average, Maximum, Minimum, Median, Deviation, or Variance extension methods when you only need aggregate values.

var exists = this.DataAccess.Exists<Thread>(
	Condition.Equal(nameof(Thread.ThreadId), threadId) &
	Condition.Equal(nameof(Thread.Visible), true));

var totalThreads = this.DataAccess.Count<Thread>(
	Condition.Equal(nameof(Thread.ForumId), forumId));

var totalViews = this.DataAccess.Sum<Thread, long>(
	nameof(Thread.TotalViews),
	Condition.Equal(nameof(Thread.ForumId), forumId));

<a name="usage-query-2"></a>

Scalar value query

Scalar queries return a single field value. They avoid loading unused fields and avoid the cost of populating a full entity.

Call description:

1. Set the generic type to the field type, or to a type that the field can be converted to;
2. Specify the entity name with the method's name argument （it must be the qualified name registered in the mapping file, i.e. container.entity; when the container name is empty, the bare entity name can be used — Discussions.UserProfile below is the qualified name from the forum module's mapping file）;
3. Specify exactly one property name with the method's schema argument.

var email = this.DataAccess.Select<string>("Discussions.UserProfile",
	Condition.Equal("UserId", userId),
	"Email" // Load only the Email field, which is a string.
).FirstOrDefault();

/* Return a scalar value set(IEnumerable<uint>) */
var counts = this.DataAccess.Select<uint>("Discussions.History",
	Condition.Equal("UserId", userId),
	"ViewedCount" // Load only the ViewedCount field.
);

<a name="usage-query-3"></a>

Multi-field Query

ThreadService.SetMostRecentThread loads only the author fields needed to update the forum's latest-thread summary. This excerpt uses the real UserProfile model:

var userId = data.GetValue(p => p.CreatorId, this.Principal.Identity.GetIdentifier<uint>());
var user = this.DataAccess.Select<UserProfile>(
	Condition.Equal(nameof(UserProfile.UserId), userId),
	$"{nameof(UserProfile.UserId)}," +
	$"{nameof(UserProfile.Name)}," +
	$"{nameof(UserProfile.Nickname)}," +
	$"{nameof(UserProfile.Avatar)}").FirstOrDefault();

data is the method's IDataDictionary<Thread> argument. This is a member-level excerpt, not a complete replacement for the method. Dictionaries and ExpandoObject are also supported for scalar projections; see DictionaryPopulatorProvider. Navigation population requires a model-shaped target; do not expect nested navigation objects in dictionary projections.

<a name="usage-query-4"></a>

Paging query

Pass a paging argument to Select to run a paged query. See Paging for the available options.

// Page 2, 25 rows per page.
var paging = Paging.Page(2, 25);

var threads = this.DataAccess.Select<Thread>(
	Condition.Equal(nameof(Thread.SiteId), siteId) &
	Condition.Equal(nameof(Thread.ForumId), 100),
	paging
);

/*
 * After the query returns, the paging object contains the result summary:
 * paging.Count is the total page count.
 * paging.Total is the total row count.
 */

<a name="usage-query-5"></a>

Sorting query

Pass Sorting values to Select to order the result. See Sorting for details.

var threads = this.DataAccess.Select<Thread>(
	Condition.Equal(nameof(Thread.SiteId), siteId) &
	Condition.Equal(nameof(Thread.ForumId), 100),
	Paging.Disabled, /* Disable paging for this query. You can pass a Paging object instead. */
	Sorting.Descending("TotalViews"),   // 1.Descending for TotalViews
	Sorting.Descending("TotalReplies"), // 2.Descending for TotalReplies
	Sorting.Ascending("CreatedTime")    // 3.Ascending for CreatedTime
);

<a name="usage-query-6"></a>

Navigation properties

Navigation(complex) properties are included through the schema argument. They support one-to-one, one-to-zero-or-one, and one-to-many relationships, and can be nested.

<a name="usage-query-7"></a>

One-to-One

/*
 * 1) Thread.Post is a one-to-one navigation property associated with Post.
 *    In the mapping file this is multiplicity="!", so the generated SQL uses INNER JOIN.
 *
 * 2) Thread.MostRecentPost is a zero-or-one navigation property associated with Post.
 *    In the mapping file this is multiplicity="?", so the generated SQL uses LEFT JOIN.
 */
var thread = this.DataAccess.Select<Thread>(
	Condition.Equal("ThreadId", 100001),
	"*,Post{*},MostRecentPost{*}"
).FirstOrDefault();

<a name="usage-query-8"></a>

One-to-Many

/*
 * 1) ForumGroup.Forums is a one-to-many navigation property.
 *    In the mapping file this is multiplicity="*", so the navigation property is loaded by a separate SQL query.
 *
 * 2) Both one-to-one and one-to-many navigation properties can be nested.
 *
 * Note: * means all scalar properties only. Navigation properties must be named explicitly.
 */
var groups = this.DataAccess.Select<ForumGroup>(
	Condition.Equal("SiteId", siteId),
	"*,Forums{*, Moderators{*}, MostRecentThread{*, Creator{*}}}"
);

<a name="usage-query-9"></a>

Navigation constraint

For one-to-many navigation properties, you often need to filter the child collection. This is called a navigation constraint.

A forum(Forum) has many forum members(ForumUser). Moderators are a subset of those forum members, and this subset is defined with complexProperty/constraints in the mapping file.

In the example below, the Users navigation property of Forum represents all forum members, while Moderators represents only the members whose IsModerator field is true.

<entity name="Forum" table="Discussions_Forum">
	<key>
		<member name="SiteId" />
		<member name="ForumId" />
	</key>

	<property name="SiteId" type="uint" nullable="false" />
	<property name="ForumId" type="ushort" nullable="false" sequence="#(SiteId)" />
	<property name="GroupId" type="ushort" nullable="false" />
	<property name="Name" type="nvarchar" length="50" nullable="false" />

	<complexProperty name="Users" port="ForumUser" multiplicity="*" immutable="false">
		<link port="SiteId" />
		<link port="ForumId" />
	</complexProperty>

	<complexProperty name="Moderators" port="ForumUser:User" multiplicity="*">
		<link port="SiteId" />
		<link port="ForumId" />

		
		<constraints>
			<constraint actor="Foreign" name="IsModerator" value="true" />
		</constraints>
	</complexProperty>
</entity>

<entity name="ForumUser" table="Discussions_ForumUser">
	<key>
		<member name="SiteId" />
		<member name="ForumId" />
		<member name="UserId" />
	</key>

	<property name="SiteId" type="uint" nullable="false" />
	<property name="ForumId" type="ushort" nullable="false" />
	<property name="UserId" type="uint" nullable="false" />
	<property name="Permission" type="byte" nullable="false" />
	<property name="IsModerator" type="bool" nullable="false" />

	<complexProperty name="User" port="UserProfile" multiplicity="!">
		<link port="UserId" />
	</complexProperty>
</entity>

<a name="usage-query-10"></a>

Navigation springboard

Sometimes a navigation property should return the target of another navigation property on the associated entity. The Moderators property above is such a case:

1. Use the colon syntax in the port attribute. The left side is the associated entity name, and the right side is the navigation property to jump to.

2. Add constraints to decide which associated rows are included.

Note: A moderator does not need to expose the forum member's Permission field. Returning UserProfile is simpler than returning ForumUser and then reading ForumUser.User. Therefore Moderators uses port="ForumUser:User".

Compare the Users and Moderators property types in the Forum class. This member excerpt preserves the nested Forum.ForumUser type; constructors, equality methods, and unrelated members are omitted:

public abstract class Forum
{
	public abstract uint SiteId { get; set; }
	public abstract ushort ForumId { get; set; }
	public abstract ushort GroupId { get; set; }
	public abstract string Name { get; set; }

	public abstract IEnumerable<ForumUser> Users { get; set; }
	public abstract IEnumerable<UserProfile> Moderators { get; set; }

	public struct ForumUser : IEquatable<ForumUser>
	{
		public uint SiteId;
		public ushort ForumId;
		public uint UserId;
		public Permission Permission;
		public bool IsModerator;

		public Forum Forum;
		public UserProfile User;
	}
}

var forum = this.DataAccess.Select<Forum>(
	Condition.Equal("SiteId", siteId) &
	Condition.Equal("ForumId", 100),
	"*, Users{*, User{Name,Email,Avatar}}, Moderators{Name,Email,Avatar}"
).FirstOrDefault();

// moderator is UserProfile (the navigation hop returns UserProfile directly, so just list its scalar properties).
foreach(var moderator in forum.Moderators)
{
	Console.Write(moderator.Name);
	Console.Write(moderator.Email);
	Console.Write(moderator.Avatar);
}

// member is ForumUser; its User navigation property leads to UserProfile.
foreach(var member in forum.Users)
{
	Console.Write(member.Permission);

	Console.Write(member.User.Name);
	Console.Write(member.User.Email);
	Console.Write(member.User.Avatar);
}

<a name="usage-query-11"></a>

Group Queries

Grouping describes grouping keys, aggregate functions and result aliases. It is separate from row paging and sorting.

Discussions defines per-forum counters on Forum, but it does not define a ForumStatistic projection or a grouped statistics service. Its real workflow updates those counters in ThreadService.SetMostRecentThread and PostService. Read that workflow before adding a separate aggregate query: stored counters and on-demand aggregates have different cost and consistency characteristics.

For grouping support itself, follow the IDataAccess.Select overloads accepting Grouping in the public contract, and the selected database driver. Choose fields from the actual mapping and a result shape matching the keys/aliases; there is no preinstalled forum statistics command to call.

<a name="usage-query-12"></a>

Navigation condition

Navigation conditions filter by fields on associated entities.

/*
 * Query history records whose related thread is valued,
 * and whose first or most recent view time is within the last 30 days.
 */
var histories = this.DataAccess.Select<History>(
	Condition.Equal("Thread.IsValued", true) & /* Navigation condition */
	(
		Condition.Between("FirstViewedTime", DateTime.Today.AddDays(-30), DateTime.Now) |
		Condition.Between("LastViewedTime", DateTime.Today.AddDays(-30), DateTime.Now)
	)
);

/* Same query, using Range.Timing to build the time range. */
var histories = this.DataAccess.Select<History>(
	Condition.Equal("Thread.IsValued", true) & /* Navigation condition */
	(
		Condition.Between("FirstViewedTime", Range.Timing.Last(30, 'D')) |
		Condition.Between("LastViewedTime", Range.Timing.Last(30, 'D'))
	)
);

<a name="usage-query-13"></a>

Subquery Filtering

ThreadService.GetIsModeratorCriteria uses a real navigation subquery to check forum membership:

return Condition.Exists("Forum.Users",
	Condition.Equal(nameof(Forum.ForumUser.UserId), this.Principal.Identity.GetIdentifier<uint>()) &
	Condition.Equal(nameof(Forum.ForumUser.IsModerator), true));

Approve, Visible and other restricted methods combine this predicate with the target thread condition. For a more complex OR expression, read ForumService.OnValidate: it calls the base validation first, then applies the whole visibility expression with criteria.And(...).

🚨 Do not rewrite this as siteCondition & publicCondition | privateCondition: the second branch would no longer be constrained by siteCondition. Retain the module validator and service authorization when adapting these excerpts.

<a name="usage-query-14"></a>

Type conversion

Use a type converter when a database field type cannot be directly converted to the entity property type.

For example, the Tags field in the Thread table is nvarchar, but the Tags property of the Thread model is a string array. Reading and writing this property requires custom conversion. See TagsConverter and the Tags property on Thread.

<a name="usage-execute"></a>

Execute operation

Execute runs a named command defined in a mapping file. Use it for SQL statements, stored procedures, and commands that do not naturally map to one entity operation. The declared mutability is the data source selector's basis for read/write routing: mutability="none" selects a readable source, while insert, update, delete, and upsert select a writable source; the selector does not inspect the SQL script to determine this. A command without an explicit mutability is treated as writable （Delete|Insert|Update）, so there is usually no need to declare it.

Discussions currently uses entity operations rather than mapped forum-statistics commands. There is no deployed Forum.GetStatistics or Forum.RefreshStatistics in its mapping. Do not invoke those names.

For an implementation reference, MetadataCommand owns the command name, alias, parameters and driver-specific scripts. Zongsoft.Data.xsd defines valid XML. A stored procedure uses type="procedure" and an alias naming an existing procedure; output parameters use the declared direction and are returned through the supplied Parameter objects. These are extension contracts, not additional Discussions features.

<a name="usage-delete"></a>

Delete operation

This fragment uses the real Post model, with caller-supplied postId and an authorized userId; it is not an excerpt of the Discussions deletion service. Use that service in application code so its authorization and attachment-cleanup workflow remain active.

this.DataAccess.Delete<Post>(
	Condition.Equal("Visible", false) &
	Condition.Equal("CreatorId", userId) &
	Condition.Equal("PostId", postId)
);

<a name="usage-delete-cascade"></a>

Cascade deletion

Cascade deletion can delete child records associated through zero-or-one, one-to-one, or one-to-many navigation properties.

this.DataAccess.Delete<Post>(
	Condition.Equal("PostId", 100023),
	"Votes"
);

<a name="usage-insert"></a>

Insert operation

this.DataAccess.Insert("Discussions.Forum", new {
	SiteId = siteId,
	GroupId = 100,
	Name = forumName
});

<a name="usage-insert-options"></a>

Insert options

DataInsertOptions controls insert-only behaviors:

• IgnoreConstraint() ignores database constraint conflicts, such as duplicate primary keys or unique keys. The failed row is skipped instead of throwing a conflict exception.
• Sequence(...) controls how sequence fields are generated. Use DataSequenceBehavior.Never when the value is supplied by the caller and should not be generated.
• Return(...) asks the database to return generated values when the current driver supports returning values.
• SuppressValidator() disables validators registered for this insert operation.

var count = this.DataAccess.Insert<Forum.ForumUser>(
	new {
		SiteId = siteId,
		ForumId = 100,
		UserId = 100,
		Permission = Permission.Read,
	},
	DataInsertOptions.IgnoreConstraint());

If you also provide a value for a sequence field, chain the sequence option:

var options = DataInsertOptions
	.Sequence(DataSequenceBehavior.Never)
	.IgnoreConstraint();

this.DataAccess.Insert<Forum>(new {
	SiteId = siteId,
	ForumId = 100,
	GroupId = 10,
	Name = "General",
}, options);

<a name="usage-insert-complex"></a>

Associated insertion

Related one-to-one and one-to-many navigation values can be inserted together.

var forum = Model.Build<Forum>();

forum.SiteId = siteId;
forum.GroupId = 100;
forum.Name = forumName;

forum.Users = new Forum.ForumUser[]
{
	new Forum.ForumUser { UserId = 100, IsModerator = true },
	new Forum.ForumUser { UserId = 101, Permission = Permission.Read },
	new Forum.ForumUser { UserId = 102, Permission = Permission.Write }
};

this.DataAccess.Insert(forum, "*, Users{*}");

<a name="usage-import"></a>

Import operation

Import is used for bulk data import. Pass the target entity name, the data collection, and the member list that should be imported.

var users = new []
{
	new { SiteId = siteId, ForumId = 100, UserId = 100, Permission = Permission.Read },
	new { SiteId = siteId, ForumId = 100, UserId = 101, Permission = Permission.Write },
};

var count = this.DataAccess.Import(
	"Discussions.ForumUser",
	users,
	"SiteId,ForumId,UserId,Permission".Split(','));

Use DataImportOptions.IgnoreConstraint() when duplicated rows should be skipped during import. It can be chained with Parameter(...) when filters or services need operation-level flags:

var options = DataImportOptions
	.IgnoreConstraint();

var count = this.DataAccess.Import(
	"Discussions.ForumUser",
	users,
	"SiteId,ForumId,UserId,Permission".Split(','),
	options);

<a name="usage-update"></a>

Update operation

var user = Model.Build<UserProfile>();

user.UserId = 100;
user.Name = name;
user.Nickname = nickname;
user.Gender = Gender.Male;

this.DataAccess.Update(user);

<a name="usage-update-dynamic"></a>

Anonymous class

The value to write can be an anonymous object, dynamic object (ExpandoObject), or dictionary (IDictionary, IDictionary<string, object>).

this.DataAccess.Update<UserProfile>(
	new {
		Name=name,
		Nickname=nickname,
		Gender=Gender.Male,
	},
	Condition.Equal("UserId", 100)
);

<a name="usage-update-schema"></a>

Exclude fields

Use schema to choose the fields to update, or to exclude fields.

/*
 * Only Name and Gender are updated.
 * Other fields are ignored even if their values changed.
 */
this.DataAccess.Update<UserProfile>(
	user,
	"Name, Gender"
);

/*
 * * allows all fields, but CreatorId and CreatedTime are excluded.
 * Even if user contains values for these two properties, no SET clauses are generated for them.
 */
this.DataAccess.Update<UserProfile>(
	user,
	"*, !CreatorId, !CreatedTime"
);

<a name="usage-update-complex"></a>

Associated Updates

The real ThreadService.Approve updates the thread and its content post in one operation:

public bool Approve(ulong threadId)
{
	var criteria = Condition.Equal(nameof(Thread.ThreadId), threadId) &
	               Condition.Equal(nameof(Thread.Approved), false) &
	               GetIsModeratorCriteria();

	return this.DataAccess.Update<Thread>(new
	{
		Approved = true,
		ApprovedTime = DateTime.Now,
		Post = new
		{
			Approved = true,
		}
	}, criteria, "*,Post{Approved}") > 0;
}

GetIsModeratorCriteria() is the private helper in the same class, shown under subquery filtering. The schema *,Post{Approved} explicitly includes the post's approval field. Do not remove the moderator predicate or the module's validator. One-to-many associated writes use upsert semantics; the exact SQL belongs to the selected driver.

<a name="usage-upsert"></a>

Upsert Operations

Upsert inserts a row when its key does not exist and updates it when it does. A real use is the browsing-history update in ThreadService.SetHistory, keyed by user and thread and incrementing ViewedCount.

🚨 The current source has a discrepancy: that method writes MostRecentViewedTime, while History and the mapping define LastViewedTime. This document does not present the method as a verified runnable example or silently correct the implementation. Align the service/model/mapping before reusing that path.

For the upsert contract and driver restrictions, see IDataAccess, DataUpsertOptions and the selected driver's README. Key matching, sequence generation, defaults on insertion and updates to existing rows must be considered separately.

<a name="usage-returning"></a>

Returning values

Delete, insert, update, and upsert options can request returned values from the database provider. This is useful for deleted file paths, identity values, generated values, and updated counters. The feature is available only when the current driver supports returning values.

var options = DataUpdateOptions.Return(ReturningKind.Newer, nameof(Thread.TotalViews));

this.DataAccess.Update<Thread>(
	new {
		TotalViews = Operand.Field(nameof(Thread.TotalViews)) + 1,
	},
	Condition.Equal(nameof(Thread.ThreadId), threadId),
	options);

if(options.Returning.Rows.Count > 0 &&
	 options.Returning.Rows[0].TryGetValue(nameof(Thread.TotalViews), ReturningKind.Newer, out var value))
{
	var totalViews = Convert.ToInt64(value);
}

For simple counters, the Increase and Decrease helpers wrap this pattern:

var totalViews = this.DataAccess.Increase<Thread>(
	nameof(Thread.TotalViews),
	Condition.Equal(nameof(Thread.ThreadId), threadId));

The following adaptation uses the real PostAttachment model to inspect returned IDs only; it does not implement file deletion:

var options = DataDeleteOptions.Return(nameof(PostAttachment.AttachmentId));

this.DataAccess.Delete<PostAttachment>(
	Condition.Equal(nameof(PostAttachment.PostId), postId),
	options);

foreach(var row in options.Returning.Rows)
{
	if(row.TryGetValue(nameof(PostAttachment.AttachmentId), out var value))
		Console.WriteLine(value);
}

<a name="usage-options"></a>

Options, events, and transactions

Every data access method accepts an option object. Options are intentionally small, but they are important because validators, filters, events, and service hooks all receive the same option instance.

Common option members:

Option member	Applies to	Description
Parameter(...) / new DataXxxOptions(parameters)	All option types	Adds operation-level parameters. These parameters are for validators, filters, callbacks, and service hooks. They are not SQL parameters; mapped commands use IEnumerable<Parameter> for SQL/stored procedure parameters.
SuppressValidator()	Select, Exists, Aggregate, Delete, Insert, Update, Upsert	Skips registered data validators for this operation. Use it only when the caller has already enforced the scope or the operation is an internal maintenance operation.
Return(...)	Delete, Insert, Update, Upsert	Requests returned values. Insert returns newer values; delete returns older values; update/upsert can request ReturningKind.Newer or ReturningKind.Older.
IgnoreConstraint()	Insert, Import, Upsert	Skips rows that conflict with database constraints when the driver supports it.
Sequence(...)	Insert, Upsert	Controls sequence generation for sequence fields.

Read option members:

Option	Description
DataSelectOptions.Distinct()	Generates a distinct query. It is especially useful for scalar or small projection queries.
DataSelectOptions.SuppressLazy(false)	Suppresses lazy loading of navigation collections. Pass true when the query should also be distinct.
DataExistsOptions.SuppressValidator()	Runs an existence check without validators.
DataAggregateOptions.SuppressValidator()	Runs a count/sum/aggregate query without validators.

Write option members:

Option	Description
DataInsertOptions.Sequence(DataSequenceBehavior.Auto)	Uses the provided sequence value when present; otherwise generates one. This is the default behavior.
DataInsertOptions.Sequence(DataSequenceBehavior.Alway)	Always lets the sequencer generate the value.
DataInsertOptions.Sequence(DataSequenceBehavior.Never)	Never generates the sequence value; use the value supplied by the caller.
DataUpdateOptions.SuppressValidator(UpdateBehaviors.PrimaryKey)	Allows primary key fields to be included in an update. This is for repair or migration code, not normal business updates.
DataUpsertOptions.IgnoreConstraint()	Applies the same conflict-ignore intent to upsert statements.

A real operation parameter is "Thread", read by PostService.OnInsert. The service accepts either a Thread model or IDataDictionary<Thread>, resolves ForumService through its service provider, then decides whether the new post is approved. Read the complete method for null handling and file-content storage. These options are operation context, not SQL parameters; there is no built-in SkipSynchronization or SkipAudit switch.

Before/after callbacks, IDataAccess events and filters expose operation stages. ThreadFilter is a real result-filtering example: OnFiltered wraps results through FilteredResult, hiding unapproved content from unauthorized readers or reading externally stored content. The wrapper preserves synchronous/asynchronous enumeration and paging notifications; read both files together.

For transaction scope, the following excerpt is the transaction body of ThreadService.OnInsert, after content validation and schema preparation:

using(var transaction = new Transaction())
{
	var count = base.OnInsert(data, schema, options);

	if(count < 1)
		return count;

	this.SetMostRecentThread(data);
	transaction.Commit();

	return count;
}

The private SetMostRecentThread helper belongs to that class. The transaction groups insertion and the related summary updates; it does not roll back external file/object-storage writes. Keep authorization and validators enabled in normal application calls.

<a name="usage-other"></a>

Other

For more details, see the related documentation for read/write splitting, inherited tables, schemas, mapping files, filters, validators, type conversion, and data isolation.

If this project is useful to you, please Watch, Fork, or Star it.

<a name="performance"></a>

Performance

Zongsoft.Data aims for balanced performance, maintainability, and usability instead of optimizing for a single benchmark. For an ORM data access engine, performance mainly depends on:

1. Generating clean and efficient SQL, using database-specific syntax when it helps;
2. Populating models/entities efficiently from query results;
3. Avoiding reflection on hot paths and caching parsed expression trees.

Because data relationships are described declaratively, the engine can turn user intent into expression trees and then into provider-specific SQL. This keeps application code focused and leaves more room for provider-level optimization.

The implementation uses emitting and dynamic compilation to prepare model population and parameter binding paths ahead of time. See ModelEmitter and related classes for details.

Plugin-Based Integration

Compose this feature through the host; a package reference supplies compile-time APIs, while plugin loading also requires deployed manifests and runtime assets. See the complete plugin workflow.

The manifest mounts the Data environment and driver collection. Add a database-driver plugin, a named connection and the application's .mapping; installing the engine alone neither selects a database nor creates tables.

Runtime artifact	Source of truth
Zongsoft.Data	Zongsoft.Data.plugin
File copying and dependencies	Zongsoft.Data.deploy

Add this fragment to an existing host .deploy (retain Main and the host’s other base manifests; do not replace the whole file):

[plugins zongsoft data]
nuget:Zongsoft.Data

Run dotnet deploy against a test deployment as explained in the workflow, with the host's framework, platform, architecture and, where needed, site. Pin compatible versions in real deployments; application dependencies such as databases, caches or commercial runtimes are still separate prerequisites.

Additional artifacts listed by the deployment manifest include Zongsoft.Data.plugin. Retain assemblies, dependencies and satellite resource directories as well. Restart the host after deployment, check plugin loading and service/driver registration, then verify the workflow above; copied files alone do not prove that the feature is active.