JsonToLinq 1.0.0-rc9

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.

📌 Default Operator Mapping

🧪 Demos

Filtering Users

// 1. Source data.
var users = new List<User>
{
  new() { Id = 1, Balance = 0, LastVisitAt = null },
  new() { Id = 2, Balance = 0, LastVisitAt = DateTime.UtcNow },
  new() { Id = 3, Balance = 0, LastVisitAt = DateTime.UtcNow.AddYears(-10) },
  new() { Id = 4, Balance = 100, LastVisitAt = null },
  new() { Id = 5, Balance = 100, LastVisitAt = DateTime.UtcNow },
  new() { Id = 6, Balance = 100, LastVisitAt = DateTime.UtcNow.AddYears(-10) },
};

// 2. JSON filter definition (simulates front-end request).
var filterJson = JsonDocument.Parse(
  """
  {
    "Logic": "&&",
    "Rules": [
      {
        "Field": "balance",
        "Operator": "=",
        "Value": 0
      },
      {
        "Logic": "||",
        "Rules": [
          {
            "Field": "lastVisitAt",
            "Operator": "=",
            "Value": null
          },
          {
            "Field": "lastVisitAt",
            "Operator": "<=",
            "Value": "2025-01-01T00:00:00Z"
          }
        ]
      }
    ]
  }
  """);

// 3. Parse JSON to LINQ expression and compile.
var filterExpr = JsonLinq.ParseToFilterExpression<User>(filterJson);
var filterLambda = filterExpr.Compile();

// 4. Apply filter.
var filteredUsers = users.Where(filterLambda);

// 5. Output results.
foreach (var fu in filteredUsers)
{
  Console.WriteLine($"Id: {fu.Id}");
}

// Id: 1
// Id: 3