如何“理解”我使用Ajax从PHP接收的数据？

Question

What I'm doing is returning an RSS feed obtained via a PHP cURL. I return $returnedData which is an associative array that looks something like this:

array(2){
        ["lastupdate"] => string(29) "Tue, 11 Feb 2014 15:25:42 GMT"
        ["feed"] => array(20) {
                    <items contained within ["feed"][0] to ["feed"][19] (very large)> 
                    }
}

I tried to run a json_encode before returning it to Ajax, but all it essentially did was convert my array into one large string. My Ajax is as follows:

$.ajaxSetup ({
        cache: false
    });

request = $.ajax ({
    type: "GET",
    url: "dataFetcher.php",
    data: arg,
});


request.done(function(response){
    var resultsArray = response;
    $("#message").text(resultsArray);
});

request.fail(function (jqXHR, textStatus, errorThrown){
    // log the error to the console
    console.error(
        "The following error occured: "+
        textStatus, errorThrown
    );
});

The thing is, I don't exactly know what I'm getting. If I do var_dump($returnedData) instead of return $returnedData I know that I get a string. But if I simply return $returnedData, I can't tell what Ajax is receiving. I tried changing the text displayed by using resultsArray[0] or resultsArray[1] or resultsArray["lastupdate"] hoping that it worked, but it didn't.

Would really appreciate it if someone could shed some light on what I'm not doing/what I'm doing wrong here.

Thanks!

Answer 1

AJAX receives the response sent by the server. I'm not a PHP programmer, but from what I've picked up reading other SO questions, you'd need to do something like:

echo json_encode($returnedData)

in your PHP script. The echo means that it's part of the output, and json_encode converts your PHP array into a JSON string, which represents the array in a way that JavaScript actually understands.

Depending on the headers of the response set in your PHP jQuery may or may not automatically parse the string as JSON, passing the resulting object/array to the success handler (as the value of the first argument) rather than just passing along the string response. You can tell it to do that (if you know the response will/should be JSON) by setting the dataType property in your $.ajax() call:

request = $.ajax ({
    type: "GET",
    url: "dataFetcher.php",
    data: arg,
    dataType: 'json'
});

Then inside your done handler function response would be the JavaScript object that matches your PHP array.

Answer 2

Two things:

1. Use json_encode in your PHP script to encode the data.
2. jQuery is interpreting the response as a string. You can either parse the response string as JSON, or you can take the easier route of setting the AJAX request to expect JSON.

So:

request = $.ajax ({
    type: "GET",
    url: "dataFetcher.php",
    data: arg,
    dataType: 'json' // <--- Your response parameter will be in JSON format by default, now.
});

Answer 3

You need to eval your response to javascript object

request.done(function(response){
    var resultsArray = response.evalJSON();
    $("#message").text(resultsArray);
});

or inside ajax call define that you will receive json

request = $.ajax ({
    type: "GET",
    url: "dataFetcher.php",
    data: arg,
    dataType: 'json'
});