发送对象数组时，Web API [FromBody]参数为null

Question

I seem to have run into an interesting problem with Web API - using this controller action, with a breakpoint on the opening brace to inspect thing :

[HttpPut]
public void Test([FromBody]object thing)
{
}

If I submit the following request (as CURL), I get the expected value which is a JObject containing the data from the body:

curl -X PUT -H "Content-Type: application/json" -d '{
    "Name": "Joe",
    "Key": { "Key": "Value" }
}' "http://localhost/api/TestController/Test"

That is, an anonymous object where Name is Joe and Key is another object containing Key = Value .

However, if I change this ever-so-slightly to instead submit an array of Keys , I get null . No error, just null .

curl -X PUT -H "Content-Type: application/json" -d '{
    "Name": "Joe",
    "Keys": [{ "Key": "Value" }]
}' "http://localhost/api/TestController/Test"

Why is this happening? The HTTP verb doesn't seem to matter (I've tried POST and PUT), and using dynamic instead of object is the same thing.

Here's some screenshots:

Answer 1

Your code is working fine when testing in Postman.

Answer 2

Turns out I had the global JSON setting for MaxDepth set to 2 elsewhere in my code, which was running before the controller action. Why this returns null and not an empty object is still beyond me, but changing this to 3 corrects the issue and functions as expected.

Sorry for the confusion everyone, thanks for the answers!

Answer 3

i think it all depends on how you wish to work with it, if you want to get a strongly typed model you can always create one like user3658685 said.

another thing you can do is bind the data to JObject and then serialize using Newton-soft Serializer:

public void Post([FromBody] JObject value)
{ 
    //instead of object you can use any type you wish to cast
    object obj = value.ToObject<object>();
}

Answer 4

WebApi uses model mapping class to try to map json object with the argument og your WebApi method. You can resolve this by creating a class with all attributes matching your json object.

public class Contract {
   public string Name { get; set; }
   public dynamic[] Keys { get; set; }
}

And changing the signature of your WebApi method with

public void Post([FromBody] Contract value)
{
}