How to change HttpContext.Response - asp.net

Question

I want that my api all the time returns the same model something like this:
result {
body: "body",
error: {
message: "message",
StatusCode: "stasusCode"
}
}
My any controller returns some model. For example:
model: {
field1: "field1",
field2: "field2"
}
I want that a middleware generate the model like this if we have successful:
result {
body: {
field1: "field1",
field2: "field2"
}
error: null
}
So how I should change response body?
If we dont have successful I implemented like this:
var result = JsonSerializer.Serialize(new
{
response = new RequestModel
{
Error = new ErrorModel
{
Message = error.Message,
StatusCode = error.Code
},
Body= null
}
});
await response.WriteAsync(result);
Please help me...

Answer 1

What you are looking for is probably a custom error handling middleware. You can create something like below code to override response or have a look here to see how you can create it as you like.
public class ErrorHandlingMiddleware
{
private readonly RequestDelegate _next;
private readonly ILogger<ErrorHandlingMiddleware> _logger;
public ErrorHandlingMiddleware(RequestDelegate next, ILogger<ErrorHandlingMiddleware> logger)
{
_next = next;
_logger = logger;
}
public async Task InvokeAsync(HttpContext context)
{
try
{
await _next(context);
}
catch (Exception e)
{
_logger.LogWarning("message to log before handling the exception", e);
await HandleException(context, e);
}
}
}
private async Task HandleException(HttpContext context, Exception exception)
{
var responseObject = JsonSerializer.Serialize(new
{
response = new RequestModel
{
Error = new ErrorModel
{
Message = error.Message,
StatusCode = error.Code
},
Body= null
}
});
var exceptionData = var data = Encoding.UTF8.GetBytes(responseObject );
_logger.LogError(exception.ToString()); // log exception if you need
context.Response.ContentType = "application/json"; // set content type
context.Response.StatusCode = (int)HttpStatusCode.InternalServerError; // status code you want to return
await context.Response.Body.WriteAsync(exceptionData, 0, exceptionData.Length, CancellationToken.None);
}