FlexQuery.NETTurn your API into a secure, composable query engine

Why FlexQuery.NET? ​

Building APIs with dynamic filtering often leads to repetitive, hardcoded LINQ queries that are brittle and difficult to scale.

FlexQuery.NET transforms this experience by providing a unified query engine that parses client-defined criteria into optimized, secure database queries.

• Stop writing endless if blocks for every filter combination.
• Reduce boilerplate by 80% while adding more power to your API.
• Enforce security and validation boundaries at the engine level.

Quick Example ​

Send a single HTTP request and get filtered, projected, and paginated results:

Request

GET /api/customers?query=name contains "Connelly"
  &select=id,name,email,orders.id,orders.status
  &include=orders(status = "cancelled")
  &pageSize=10

Controller

[HttpGet]
public async Task<IActionResult> Get([FromQuery] QueryRequest request)
{
    // 1. Parse query into internal options
    var options = QueryOptionsParser.Parse(request);
    
    // 2. Execute full pipeline: Filter + Sort + Paging + Projection
    var results = await _context.Users
        .ToProjectedQueryResultAsync(options);

    return Ok(results);
}

Choose Your Level of Control ​

FlexQuery.NET is built as a layered system, allowing you to choose the perfect balance between abstraction and flexibility.

• Low-level: Atomic control over individual steps using ApplyFilter, ApplySort, ApplyPaging.
• Mid-level: High-level logic composition with ApplyQueryOptions or ApplyValidatedQueryOptions.
• High-level: Full execution, pagination, and data shaping with ToProjectedQueryResultAsync.

Features ​

🔍 Querying ​

• Dynamic Filtering: DSL, JSON, Indexed, and JQL query formats supported out of the box.
• Multi-field Sorting: Order by nested properties and aggregate functions (sum, count, max, min, avg).
• Paging: High-performance pagination optimized for large relational datasets.

🏗️ Data Shaping ​

• Projection: Select only the fields you need with select and powerful field aliases.
• Includes: Load and filter related collections independently using the Dual-Pipeline system.

🛡️ Safety ​

• Validation Engine: Pre-execution validation for field existence, operator validity, and type safety.
• Field-Level Security: Built-in whitelisting and blacklisting of fields with nested path support.

⚡ Architecture ​

• EF Core Translation: Expression-tree based, fully translatable to SQL by your database provider.
• Dual-Pipeline: Decouples root entity filtering (WHERE) from child data shaping (Filtered Includes).

Is FlexQuery.NET for you? ​

✅ Use it when: ​

• Building Admin Dashboards with complex, multi-column filtering requirements.
• Creating Reporting Systems that need dynamic aggregates and grouping.
• Developing Flexible APIs where clients need to define the data shape and scope.

❌ Not for you if: ​

• You only have simple CRUD endpoints with static query requirements.
• Your business logic requires strictly Hardcoded Queries that should never be modified by clients.
• You need the full features of GraphQL or the enterprise standards of OData.

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