CODEWITHSUNDEEP
c#asp.netasp.net-web-api
Scott
Scott

Reputation: 5369

Web API [FromBody] parameter is null when sending an array of objects

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: enter image description here enter image description here

Upvotes: 1

Views: 9359

Answers (4)

Win
Win

Reputation: 62260

Your code is working fine when testing in Postman.

enter image description here

enter image description here

Upvotes: 2

Erez.L
Erez.L

Reputation: 85

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>();
}

Upvotes: 1

user3658685
user3658685

Reputation: 1

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)
{
}

Upvotes: 0

Scott
Scott

Reputation: 5369

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!

Upvotes: 1

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