Can not deserialize instance of java.util.arraylist out of start_object token

Question

Problem :

I want to POST the List of custom objects. My JSON in a request body is as below :

{
    "collection": [
        {
            "name": "Test ordert1",
            "detail": "ahk ksa"
        },
        {
            "name": "Test ordert2",
            "detail": "Fistekua"
        }
    ]
}

 

But I am facing below error:

“Can not deserialize instance of java.util.arraylist out of start_object token”

How can I fix the above error?

Answer 1

The problem is in the JSON - this cannot, by default, be the deserialized into the Collection because it's not actually the JSON Array - that would look like below:

[
    {
        "name": "Test ordert1",
        "detail": "ahk ksa"
    },
    {
        "name": "Test ordert2",
        "detail": "Fistekua"
    }
]

As you are not controlling a exact process of a deserialization (RestEasy does)

The first option - would be to just inject a JSON as the String and then take the control of a deserialization process as below:

Collection<COrder> readMyValues = new ObjectMapper().readMyValue(
    jsonAsMyString, new TypeReference<Collection<COrder>>() { }
);

You would loose the bit of a convenience of not having to do that by yourself, but you would easily sort out a problem.

Second option - If you cannot change a JSON - would be to construct the wrapper to fit a structure of the JSON input - and use that instead of the Collection<COrder>.