Request Contracts

HTTP request contracts define the shape of your API calls using interfaces and attributes. Every HTTP contract implements IHttpRequest<TResult> and is decorated with attributes that describe the HTTP verb, route, parameters, and body.

IHttpRequest<TResult>

All HTTP contracts must implement IHttpRequest<TResult> where TResult is the deserialized response type.

using Shiny.Mediator.Http;

[Http(HttpVerb.Get, "/api/users/{Id}")]
public class GetUserRequest : IHttpRequest<UserResponse>
{
    [HttpParameter(HttpParameterType.Path)]
    public string Id { get; set; }
}

Note

HTTP requests work only as Request contracts. If you do not require a response, you can use IRequest<HttpResponseMessage>.

The [Http] Attribute

The [Http] attribute defines the HTTP verb and route template for the request.

[Http(HttpVerb.Get, "/api/resource")]
[Http(HttpVerb.Post, "/api/resource")]
[Http(HttpVerb.Put, "/api/resource/{Id}")]
[Http(HttpVerb.Patch, "/api/resource/{Id}")]
[Http(HttpVerb.Delete, "/api/resource/{Id}")]

HTTP Verb Examples

GET - Retrieve data

[Http(HttpVerb.Get, "/api/products")]
public class GetProductsRequest : IHttpRequest<List<Product>>
{
    [HttpParameter(HttpParameterType.Query)]
    public string Category { get; set; }

    [HttpParameter(HttpParameterType.Query)]
    public int Page { get; set; } = 1;
}

POST - Create a resource

[Http(HttpVerb.Post, "/api/products")]
public class CreateProductRequest : IHttpRequest<Product>
{
    [HttpBody]
    public CreateProductDto Body { get; set; }
}

PUT - Replace a resource

[Http(HttpVerb.Put, "/api/products/{Id}")]
public class UpdateProductRequest : IHttpRequest<Product>
{
    [HttpParameter(HttpParameterType.Path)]
    public string Id { get; set; }

    [HttpBody]
    public UpdateProductDto Body { get; set; }
}

PATCH - Partially update a resource

[Http(HttpVerb.Patch, "/api/products/{Id}")]
public class PatchProductRequest : IHttpRequest<Product>
{
    [HttpParameter(HttpParameterType.Path)]
    public string Id { get; set; }

    [HttpBody]
    public PatchProductDto Body { get; set; }
}

DELETE - Remove a resource

[Http(HttpVerb.Delete, "/api/products/{Id}")]
public class DeleteProductRequest : IHttpRequest<Product>
{
    [HttpParameter(HttpParameterType.Path)]
    public string Id { get; set; }
}

The [HttpParameter] Attribute

The [HttpParameter] attribute maps a property to a specific part of the HTTP request. There are three parameter types:

Path Parameters

Path parameters are substituted into the route template. The property name must match the {placeholder} in the route.

[Http(HttpVerb.Get, "/api/users/{UserId}/orders/{OrderId}")]
public class GetOrderRequest : IHttpRequest<OrderResponse>
{
    [HttpParameter(HttpParameterType.Path)]
    public string UserId { get; set; }

    [HttpParameter(HttpParameterType.Path)]
    public string OrderId { get; set; }
}

Query Parameters

Query parameters are appended to the URL as query string values.

[Http(HttpVerb.Get, "/api/search")]
public class SearchRequest : IHttpRequest<SearchResults>
{
    [HttpParameter(HttpParameterType.Query)]
    public string Term { get; set; }

    [HttpParameter(HttpParameterType.Query)]
    public int PageSize { get; set; } = 25;

    [HttpParameter(HttpParameterType.Query)]
    public string SortBy { get; set; }
}

// Resulting URL: /api/search?Term=hello&PageSize=25&SortBy=name

Value Formatting

Path, query and header values are formatted by HttpParameterFormatter, so the URL is the same no matter which culture the device runs in:

Type	Sent as
DateTimeOffset, DateTime	Round-trip ISO 8601 (2026-09-04T21:46:57.0000000+00:00)
DateOnly	yyyy-MM-dd
TimeOnly	HH:mm:ss (fractional seconds when present)
Numbers (int, decimal, double, …)	Invariant culture (1234.5, never 1234,5)
bool	true / false
Enums	Member name (numeric OpenAPI enums are sent as their value)

Path and query values are URL-encoded, and null query values are skipped. A collection property (List<T>, T[], HashSet<T>, …) repeats the parameter once per item:

[HttpParameter(HttpParameterType.Query)]
public List<string> Tag { get; set; }   // ?Tag=a&Tag=b

Don’t escape or pre-format values yourself — they would be encoded twice.

Header Parameters

Header parameters are added as HTTP request headers.

[Http(HttpVerb.Get, "/api/data")]
public class GetDataRequest : IHttpRequest<DataResponse>
{
    [HttpParameter(HttpParameterType.Header)]
    public string ApiVersion { get; set; } = "2.0";

    [HttpParameter(HttpParameterType.Header)]
    public string CorrelationId { get; set; }
}

The [HttpBody] Attribute

The [HttpBody] attribute marks a property to be serialized as the JSON request body.

[Http(HttpVerb.Post, "/api/orders")]
public class CreateOrderRequest : IHttpRequest<OrderResponse>
{
    [HttpBody]
    public OrderDto Order { get; set; }
}

There can only be one [HttpBody] property per contract. The body is serialized to JSON.

Complete CRUD Example

Here’s a full set of contracts for a typical CRUD API:

using Shiny.Mediator;
using Shiny.Mediator.Http;

// List
[Http(HttpVerb.Get, "/api/products")]
public class ListProductsRequest : IHttpRequest<List<Product>>
{
    [HttpParameter(HttpParameterType.Query)]
    public string Category { get; set; }

    [HttpParameter(HttpParameterType.Query)]
    public int Page { get; set; } = 1;

    [HttpParameter(HttpParameterType.Query)]
    public int PageSize { get; set; } = 25;
}

// Get by ID
[Http(HttpVerb.Get, "/api/products/{Id}")]
public class GetProductRequest : IHttpRequest<Product>
{
    [HttpParameter(HttpParameterType.Path)]
    public string Id { get; set; }
}

// Create
[Http(HttpVerb.Post, "/api/products")]
public class CreateProductRequest : IHttpRequest<Product>
{
    [HttpBody]
    public CreateProductDto Body { get; set; }
}

// Update
[Http(HttpVerb.Put, "/api/products/{Id}")]
public class UpdateProductRequest : IHttpRequest<Product>
{
    [HttpParameter(HttpParameterType.Path)]
    public string Id { get; set; }

    [HttpBody]
    public UpdateProductDto Body { get; set; }
}

// Delete
[Http(HttpVerb.Delete, "/api/products/{Id}")]
public class DeleteProductRequest : IHttpRequest<Product>
{
    [HttpParameter(HttpParameterType.Path)]
    public string Id { get; set; }
}

Usage:

IMediator mediator; // injected

// List products
var products = await mediator.Request(new ListProductsRequest
{
    Category = "electronics",
    Page = 1
});

// Get single product
var product = await mediator.Request(new GetProductRequest { Id = "123" });

// Create product
var created = await mediator.Request(new CreateProductRequest
{
    Body = new CreateProductDto { Name = "Widget", Price = 9.99m }
});

// Update product
var updated = await mediator.Request(new UpdateProductRequest
{
    Id = "123",
    Body = new UpdateProductDto { Name = "Updated Widget", Price = 12.99m }
});

// Delete product
var deleted = await mediator.Request(new DeleteProductRequest { Id = "123" });

Combining All Parameter Types

A single contract can use path, query, header, and body parameters together:

[Http(HttpVerb.Post, "/api/v1/tenants/{TenantId}/items")]
public class CreateItemRequest : IHttpRequest<ItemResponse>
{
    [HttpParameter(HttpParameterType.Path)]
    public string TenantId { get; set; }

    [HttpParameter(HttpParameterType.Query)]
    public bool Validate { get; set; } = true;

    [HttpParameter(HttpParameterType.Header)]
    public string CorrelationId { get; set; }

    [HttpBody]
    public CreateItemDto Body { get; set; }
}