Cannot return null from an action method with a return type of 'Microsoft.AspNetCore.Mvc.JsonResult'
Context: I created a simple app which displays card view items on view. I have added a file picker in there. Once the file picker selected an image and the save button has been clicked, my code triggered the exception
System.InvalidOperationException: Cannot return null from an action method with a return type of 'Microsoft.AspNetCore.Mvc.JsonResult'.
My Rider does not let me debug like this (as per attached screenshot) so I have no idea what caused this exception.
My full code here. Could anyone kindly point me in the right direction?
https://paste.mod.gg/bnhhtfmvhaku/0BlazeBin - bnhhtfmvhaku
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2 Replies
if you return
Ok(model) it will serialize it to JSON for you and null values are permitted then. You generally shouldn't need to use the underlying XXXResult objects
For example Ok has an underlying type OkObjectResult which you could use but it's a lot easier to just return Ok(model) instead of return new OkObjectResult(model)
Do be aware though if you return a string or int (or any other value type) with Ok() it wont serialize it for you.
would show:
Generally I'd recommend using the return type IActionResult unless you have specific requirements too, ie public async Task<IActionResult> CreateUserIactionResult is a decent way to do it, but Results is better
Here's the gist of it: https://gist.github.com/Atulin/7b9747ff316b864f7c305ac1bc96fab5