Lyo.Query.Evaluation 2.0.0

Lyo.Query.Evaluation

This slice of the query engine turns a WhereClause into an expression tree and evaluates it. Every IWhereClauseService member is implemented here except caching, which Lyo.Query adds by overriding this package's virtual members.

The split exists because Lyo.Validation needs exactly this and nothing else. Evaluating a ValidationSchema used to mean referencing Lyo.Query, which pulled in cache, encryption, hashing, key store, compression, and health. WhereClauseEvaluator uses a ConcurrentDictionary instead of the shared cache, so a consumer that only wants to know whether an object matches a clause pays for expression building and nothing else.

Metrics are recorded here rather than in Lyo.Query, because Lyo.Metrics has no NuGet dependencies of its own. IMetrics is an optional constructor parameter that defaults to NullMetrics.Instance, so the uninstrumented path costs nothing.

Features

• In-memory matching. MatchesWhereClause against a compiled predicate.
• Match explanation. ExplainMatch produces the WhereClauseExplainNode tree that validation turns into errors.
• Queryable translation. ApplyWhereClause, SortByProperty, and ApplyOrdering against IQueryable<T>.
• Path resolution. Dotted paths, including collection segments, go through TryValidatePropertyPath and SharedEntityMetadataCache.
• Value conversion. Filter literals go through IValueConversionService / ValueConversionService, which delegates to TypeConversion.
• Metrics. Durations, success counters, and errors under Lyo.Query.Constants.Metrics, tagged entity_type. Pass an IMetrics to opt in; omit it and nothing is recorded or allocated.
• Extension points. GetMatcher, GetEfPredicate, and GetIncludePaths are virtual so a host can plug in its own caching.

Examples

Evaluate a clause without Lyo.Query

using Lyo.Query.Services.ValueConversion;
using Lyo.Query.Services.WhereClause;

IWhereClauseService where = new WhereClauseEvaluator(new ValueConversionService());

var clause = new ConditionClause("Status", ComparisonOperatorEnum.In, new[] { "Open", "Pending" });
if (!where.MatchesWhereClause(order, clause))
    Console.WriteLine(where.ExplainMatch(order, clause).FailureSummary);

Smallest DI wiring

services.TryAddSingleton<IValueConversionService, ValueConversionService>();
services.TryAddSingleton<IWhereClauseService, WhereClauseEvaluator>();

Record metrics without Lyo.Query

using Lyo.Metrics;

// Pass an IMetrics to instrument evaluation. Omitting it uses NullMetrics.Instance.
var metrics = new MetricsService();
IWhereClauseService where = new WhereClauseEvaluator(new ValueConversionService(), metrics);

where.MatchesWhereClause(order, clause);

var successes = metrics.GetCounterValue(
    Lyo.Query.Constants.Metrics.MatchesWhereClauseSuccess,
    tags: [(Lyo.Query.Constants.Metrics.Tags.EntityType, nameof(Order))]);

How this relates to Lyo.Query

Lyo.Query.BaseWhereClauseService subclasses WhereClauseEvaluator and overrides the protected GetMatcher / GetEfPredicate / GetIncludePaths members to go through ICacheService. It also forwards the injected IMetrics only when CacheOptions.EnableMetrics is set, since that flag lives in Lyo.Cache and cannot be read from here. IWhereClauseService signatures are the same either way, so nothing downstream can tell which one it got.

Take this package when the consumer only evaluates clauses. Take Lyo.Query when the consumer wants the shared cache and the rest of the request/paging surface.

netstandard2.0 caveat

On net targets, IWhereClauseService.ExplainMatch ships a default implementation so database-only services need not implement it. netstandard2.0 has no default interface implementations, so the member is abstract there and implementers must supply it.

Dependencies

Generated from ProjectReference / PackageReference (same model as docs/Lyo.ProjectGraph.html).

• Lyo.Common.Core (direct, lyo)
• Lyo.Exceptions (direct, lyo)
• Lyo.Metrics (direct, lyo)
• Lyo.Query.Models (direct, lyo)
• Lyo.Common.Json (transitive, lyo)
• Lyo.Common.Metadata (transitive, lyo)
• Lyo.Parameters (transitive, lyo)
• Microsoft.Bcl.AsyncInterfaces 10.0.5 (transitive, microsoft, netstandard2.0)
• System.Memory 4.6.3 (transitive, microsoft, netstandard2.0)
• System.Text.Json 10.0.5 (transitive, microsoft, netstandard2.0)