VanDerHeijden.JsonBodyProvider

ASP.NET Core custom value provider Allows you to bind multiple simple parameters directly from a JSON request body — without using [FromBody] and without wrapper DTO classes.

Main purpose Call controller actions like this:

[HttpPost]
public IActionResult CreateUser(
    string Name,
    int Age,
    List<string> Roles,
    Guid TenantId,
    DateOnly StartDate,
    bool IsActive,
    string? Comment = null)
{
    // ← all parameters automatically come from JSON body
}

Most important facts first

Works only without [ApiController] attribute [ApiController] breaks this completely → remove it from the controller

Installation

dotnet add package JsonBodyProvider

Recommended minimal startup configuration

builder.Services
    .AddControllers()                       // ← no [ApiController] !
    .AddJsonBodyProvider(CorrectLists: true);  // ← enables normal list + string behaviour

Good real-world examples

Example 1 – Classic user creation

[Route("api/users")]
public class UsersController : ControllerBase
{
    [HttpPost]
    public IActionResult Create(
        string Name,
        int Age,
        string Email,
        List<string> Roles,
        bool IsActive = true)
    {
        // ...
    }
}

POST /api/users
Content-Type: application/json

{
  "Name": "Lisa van Dijk",
  "Age": 34,
  "Email": "lisa@example.com",
  "Roles": ["editor", "reviewer"],
  "IsActive": true
}

Example 2 – Order with items

[HttpPost("orders")]
public IActionResult PlaceOrder(
    string OrderNumber,
    DateOnly OrderDate,
    decimal TotalAmount,
    List<string> ProductCodes,
    Guid CustomerId,
    string? Remark = null)
{
    // ...
}

{
  "OrderNumber": "ORD-2025-78412",
  "OrderDate": "2025-06-18",
  "TotalAmount": 1249.95,
  "ProductCodes": ["PROD-A42", "PROD-B17", "PROD-C09"],
  "CustomerId": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "Remark": ""
}

Example 3 – Very flat analytics event

[HttpPost("events")]
public IActionResult TrackEvent(
    string EventName,
    string UserId,
    DateTime Timestamp,
    int Value,
    Dictionary<string, string> Properties,
    bool IsConversion,
    Guid? CampaignId)
{
    // ...
}

{
  "EventName": "purchase_completed",
  "UserId": "usr_9k3j2p8x",
  "Timestamp": "2025-06-18T14:22:09Z",
  "Value": 1,
  "Properties": {
    "Category": "electronics",
    "Source": "newsletter"
  },
  "IsConversion": true,
  "CampaignId": null
}

Example 4 – Very minimal update

[HttpPatch("items/{id}")]
public IActionResult PatchItem(
    Guid id,
    string? Title,
    string? Description,
    bool? Active,
    int? Priority)
{
    // only the fields that are sent will be bound
}

{
  "Title": "Updated task name",
  "Priority": 3
}

What you get for free

• Multiple parameters from one JSON body
• No need for [FromBody] on every parameter
• No wrapper DTO needed
• Empty strings stay empty strings
• Lists behave nicely (no random fallback to default(T) on parse errors)
• Headers and cookies are also available as parameters (optional)

Golden rule (repeat until it hurts)

Do NOT use [ApiController] on controllers where you want to use this package

If you really need [ApiController] → you cannot use this style of multi-parameter binding

License

MIT