JsonToLinq 1.0.0-rc911

JsonToLinq

JsonToLinq - lightweight C# library that converts JSON-based query definitions into LINQ expressions. Ideal for building dynamic filters, predicates, and queries.

🎯 Use Cases

JsonToLinq can be applied in various scenarios where dynamic, runtime-defined queries are needed. Examples include:

• Server-side filtering: Apply JSON-defined filters received from front-end applications to collections or database queries.
• Dynamic reporting: Build complex filters and predicates for reports without hardcoding logic.
• Custom dashboards: Let users define queries for dashboards dynamically and translate them to LINQ expressions.
• EF Core / Entity Framework queries: Map JSON filters directly to LINQ queries executed on the database.
• Audit & logging filters: Dynamically select subsets of data based on JSON rules for auditing or logging purposes.

🚀 Quick Start

using Neomaster.JsonToLinq;

var users = source.Where(
  """
  {
    "Logic": "&&",
    "Rules": [
      {
        "Field": "balance",
        "Operator": "=",
        "Value": 0
      },
      {
        "Logic": "||",
        "Rules": [
          {
            "Field": "lastVisitAt",
            "Operator": "=",
            "Value": null
          },
          {
            "Field": "lastVisitAt",
            "Operator": "<=",
            "Value": "2025-01-01T00:00:00Z"
          }
        ]
      }
    ]
  }
  """);

🛠️ Operators

👓 Operators and their handling logic are encapsulated in class ExpressionOperatorMapper. The default operator mapping can be accessed via property Pairs.

🔠 String comparisons are case-sensitive, depending on the database collation, not on the operators.

📌 Default Operators

🌟 Add Custom Operators

JsonLinq.Configure(options =>
  {
    options.OperatorMapper
      .Add("lt", Expression.LessThan)
      .Add("gt", Expression.GreaterThan);
  });

🔬 Demos and Experiments

This repository contains a project with working examples. You are welcome to submit a PR with your own examples, bug reports, or new features. To describe a filter, use the following notation:

🔤 Filter Notation

Syntax

expr = logic[expr(, expr)*]

• expr - a single rule or a combination of rules
• logic - an operator used to combine multiple rules, e.g. &&, &, ||, |, or a custom one

Examples

1. &&[x = null]
2. &&[a < 0, b > 0]
3. &&[x = null, ||[a < 0, b > 0]]

💻 Demo Project

This project provides examples of working with EF Core and a PostgreSQL database.

🧪 A real database is used instead of in-memory storage, ensuring clean and realistic experiments.

➕ You can add your own examples with other databases or ORMs via a PR.

▶️ Before running the demos, select the first menu item, Prepare Data, to apply migrations and populate the tables with test data.