LHSBrackets.ModelBinder

A .NET modelbinder for parsing query parameters that use the LHS Brackets syntax commonly used in REST APIs.

Platforms - .NET 5.0

Supported operators:

• [eq] - equal to
• [ne] - not equal to
• [gt] - greater than
• [gte] - greater than or equal to
• [lt] - less than
• [lte] - less than or equal to
• [in] - contained in array
• [nin] - not contained in array

Example request: GET https://localhost:3000/api/books?releaseDate[gte]=2021-01-01&authorId[in]=1,2,3&price[lt]=10

Model binding

LHSBrackets.ModelBinder

The model binder is using en-GB culture for now. Might be updated to take a culture input at a later date.

// Startup.cs
services.AddControllers(options => {
    options.ModelBinderProviders.Insert(0, new FilterModelBinderProvider());
})

// Define your own request model that derives from FilterRequest
public class BooksFilterRequest : FilterRequest
    {
        public FilterOperations<Guid> AuthorId { get; set; }
        public FilterOperations<DateTime> ReleaseDate { get; set; }
        public FilterOperations<decimal?> Price { get; set; }
    }

// Controller action - GET request
[HttpGet]
public async Task<IActionResult> GetBooks(
    [FromQuery] BooksFilterRequest filterRequest, // this uses the LHSBrackets model binder
    [FromQuery] string? someOtherRandomQuery // this uses the built-in model binder
)
{
    // stuff
}

Entity Framework

LHSBrackets.ModelBinder.EF

You can apply the filters to Linq statements for database queries. This will apply all LHS bracket-operations from the filter request that have values.

[HttpGet]
public async Task<IActionResult> GetBooks([FromQuery] BooksFilterRequest filterRequest)
{
    var books = await _dbContext.Books
        .ApplyFilters(x => x.AuthorId, filterRequest.AuthorId)
        .ApplyFilters(x => x.ReleaseDate, filterRequest.ReleaseDate)
        .ApplyFilters(x => x.Price, filterRequest.Price)
        .ToListAsync();
}

Swagger (upcoming)

nuget: LHSBrackets.ModelBinder.Swashbuckle

Swashbuckle support for generating accurate openapi 3.0 specifications coming up.