Question

I have 2 JS files, one containing a list of generic functions to be shared between multiple files called “form.js”, and another specific to a certain page on my CMS called “blog.form.js”.

Inside “form.js”, I have a generic JS function that makes a jQuery.ajax() request whenever I’ve requested to load a record from the database:

function load_record( field_id, class_name, entity_type ) {

// Send ajax request to load the record, and enable the form's state once the record's content has been received.
var response = $.ajax({
    async: false,
    dataType: "json",
    data: {
        action: "load_"+entity_type,
        id: $("#"+field_id+"_list").val()
    },
    success: function(response) {
        // Make visible the buttons to allow actions on record, such as deleting or renaming.
        $("#"+field_id+"_actions").show();

        // Make visible the container of all form elements related to the record.
        $("#"+field_id+"_form_inputs").show();

        // Must return response so the calling JS file can use the values returned to
        // populate the form inputs associated with the record that's just been loaded
        // with the correct values.
        return response;
    },
    type: "post",
    url: "/ajax/record/"+class_name
});
alert( response.link + " " + response + " " + response.responseText);
return response;

}

Inside “blog.form.js”, I have function called when I select a database record to load from a menu containing a list of them:

// Select a link for editing.
$("#links_list").live( "change", function(){ 
    // Insert response returned from function call to load the db record into a variable.
    // This is so the form inputs associated with the record loaded can be populated with the correct values. 
    var response = load_record('links_edit', 'blog', 'link'); 
    alert( response.link );
    $("#links_edit_url").val( response.link );        
});

The ajax request returns the desired response. Unfortunately, the debug alert statement “alert( response.link + ” ” + response + ” ” + response.responseText)” inside load_record() returns the following: undefined [Object XMLHTTPRequest] {“link”: “http://www.url.com”}.

Thus, the debug alert statement “alert( response.link )” in the other function returns undefined as well.

An XMLHTTPRequest object is returned successfully. So, why is response.link stating its value is undefined?

Any help is much appreciated.

Answer 1

You were totally on the right track, and you can make a function that returns an ajax object. jQuery returns that ajax call as a Deferred object – so it has extra methods on it to tap into the ajax response after the fact.

$("#links_list").live( "change", function(){ 
    load_record('links_edit', 'blog', 'link').done( function( response ) {
        alert( response.link );
        $("#links_edit_url").val( response.link );     
    });
});

The alert( response.link + " " + response + " " + response.responseText); in load_record will keep returning as it has been unless you add it to the success or done handlers.

Take a look at Deferreds on jquerys site with the link above if you need some more info on what .done() really is. I hope this helps.