GREsau / GREsau.AspNetCore

Utilities for ASP.NET Core

GREsau.AspNetCore

Utilities for ASP.NET Core web applications.

Installing

Install via NuGet:

> dotnet add package GREsau.AspNetCore

JSON Property Model Metadata Names

Basic usage:

services.AddControllers().AddJsonPropertyModelMetadataNames();

By default, when model validation fails, MVC will use the C# property names in the resulting ValidationProblemDetails. This will typically returned to the client as a JSON body of a 400 Bad Request response.

For example, given the model class:

public class MyModel
{
    [Range(1, 100)]
    [JsonPropertyName("foo")]
    public int Number { get; set; }

    [Required]
    public string Text { get; set; }
}

If the client POSTs the JSON { "foo": 0 } to a controller that takes MyModel, then they will receive a 400 with a body similar to:

{
  "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1",
  "title": "One or more validation errors occurred.",
  "status": 400,
  "traceId": "|01234567-0123456789abcdef.",
  "errors": {
    "Number": [
      "The field Number must be between 1 and 100."
    ],
    "Text": [
      "The field Text is required."
    ]
  }
}

...even though the client would have no prior knowledge of the identifier Number. To make MVC use the identifier foo instead, you can use this library's AddJsonPropertyModelMetadataNames() extension method on IMvcBuilder (or IMvcCoreBuilder), e.g. in your Startup class:

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers().AddJsonPropertyModelMetadataNames();
}

Then, the response body would be:

{
  "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1",
  "title": "One or more validation errors occurred.",
  "status": 400,
  "traceId": "|01234567-0123456789abcdef.",
  "errors": {
    "foo": [
      "The field foo must be between 1 and 100."
    ],
    "text": [
      "The field text is required."
    ]
  }
}

Be aware this will alter the name used for model binding of any properties, unless they are explicitly overridden (e.g. using a [BindProperty(Name = "...")] attribute). However, it will not alter the model binding name for any method parameters, or properties of a controller (any subclass of ControllerBase).