Question

I have a function A which loads the data from db if the user has liked the image. I have another function B which loads the count for the total number of likes for the image. Both these functions return response using JSON.

If I call them individually, everything works fine, but if I call function B in function A, I get no JSON response and nothing happens although firebug does show two JSON arrays being outputted.

What is wrong with the code?

Function A:

public function loadLikes() {
        //sql query

            try
            {


                $query = $this->_db->prepare($sql);
        $params = array(':imageid' => $imageid, ':author' => $author);
        $query->execute($params); 

                //calling function B
                $this->countLikes($imageid);

                if ($query->rowCount() > 0) {

                    while ($row = $query->fetch(PDO::FETCH_ASSOC)) {
                    if ($row['like'] == '1') {
                        $response = json_encode(array('like' => true));
                        echo $response;
                        return TRUE;
                    }
                    elseif ($row['like'] == '2')  {
                        $response = json_encode(array('unlike' => true));
                        echo $response;
                        return TRUE;
                    }
                    else {
                        $error = "Invalid";
                        $response = json_encode(array('like' => false, 'text' => $error));
                        echo $response;
                        return FALSE;
                    }
                  }

                }
                else {

                    $response = json_encode(array('unlike' => true));
                    echo $response;
                    return FALSE;
                }

            }
            catch(PDOException $ex)
            {
                echo json_encode(array('like' => false, 'text' => $ex));
                return FALSE;
            }

    }

Function B:

public function countLikes($i) {
        //sql query

            try
            {           
                $query = $this->_db->prepare($sql);
                $params = array(':imageid' => $i);
                $query->execute($params); 

                if ($query->rowCount() > 0) {
                    $count = $query->fetchColumn();
                    $response = json_encode(array('count' => $count));
                    echo $response;
                    return TRUE;
                }


            }
            catch(PDOException $ex)
            {

                return FALSE;
            }

    }

jQuery:

$.ajax({
                            type: "POST",
                            url: url,
                            data: postData, 
                            dataType: "json",
                            success: function(data){
                                $(".count-like").show(600).text(data.count);
                                if(data.like) {
                                    $("a#alike").attr('class', 'starred');  
                                }
                                else if (data.unlike) {
                                    $("a#alike").attr('class', 'unlike');
                                }
                                else {
                                    alert(data.text);
                                }
                            }
                        });

Answer 1

If you invoke both functions, then each will output a JSON array. This will result in a HTTP response with following content:

{"like":1}{"count":2}

Both arrays would be valid separately. But if concatenated like this, it’s no longer valid JSON.

Instead of outputting the json serialization with echo you should collect it in a temporary variable, merge the two arrays, and then output the combined array with a single:

echo json_encode(array_merge($countArray, $likeArray));

Example adaptions of your code

Function B should become:

public function countLikes($i) {
    //sql query

        try
        {           
            $query = $this->_db->prepare($sql);
            $params = array(':imageid' => $i);
            $query->execute($params); 

            if ($query->rowCount() > 0) {
                $count = $query->fetchColumn();

                /* JUST RETURN HERE */
                return (array('count' => $count));
            }


        }
        catch(PDOException $ex)
        {

            /* INSTEAD OF FALSE use an empty array,
               which is interpreted as false in boolean context*/
            return array();
        }

}

Then when you call the function:

//calling function B
$countArray = $this->countLikes($imageid);

This will always be an array. Which you then can use in the output code:

$response = json_encode(array('like' => true) + $countArray);

(It’s still inadvisable to have an echo right there. But too much code, too little context to propose a nicer rewrite. And if it works, ..)