Dealing with a missing response in an Ajax Server-Side Call: The .done(function(data){..} function remains inactive

Let's say I make an Ajax server-side call using jQuery like this:

    $.ajax({
        url: "/myapp/fetchUser?username=" + username, 
        type : "get",
        dataType : "json",
        data : ''
    }).done(function(data) {
        console.log(data);
    });
}  

On the server-side, in Java, the fetchUser endpoint retrieves a JSON-serialized UserT object from the database. This object can either exist or be NULL. When the object exists, the code successfully executes the JS logic within .done(function(data) {..}. However, when the object returned is NULL, the JS code inside .done(function(data) ..) does not run.

Is there a way to handle a NULL response in jQuery? Currently, the execution halts if the response is NULL.

Answer №1

Ensure dataType : "json", is set in your request to guarantee valid json response, even if it is just {}. Modify your endpoint to consistently return valid json or remove this option from the ajax request and manually parse the response.

The reason why done is not triggered is because jQuery attempts to parse null, resulting in an error and triggering the error callback instead.

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