JQuery Do something when data returned from .post

Question

I have a site that is sending off using the .post function in JQuery to run a php script. This script adds some data to a database but if the data already exists in the database it doesn't add the data. Depending on whether the data is added or not I want the javascript to do different things. I don't know how to get the php to return a value that says "data entered" or "data not entered" so the javascript can use that value to decided upon it next action.

Here is the javascript, I only want the append to happen if the php returns that the data was entered into the database.

$('#addpios').click(function() {
  var scopesheetidvalue = $("#scopesheetid").val();
  var piovalue = $("#pioselected").val();
$.post("addpio.php", { scopesheetid: scopesheetidvalue, pionumber: piovalue },function(data){
$('#pioslist').append("<li><input class='removepio' type='submit' value='"+piovalue+"' /><span class='listitem'>PIO "+piovalue+"</span></li>");} 
    );   
}); 

Here is the PHP

$scopesheetid = $_POST['scopesheetid'];
$pionumber = $_POST['pionumber'];
$alreadyexisitssql = "SELECT * FROM [ScopesheetPIO] WHERE [ScopesheetID]='$scopesheetid' AND [PIONumber]='$pionumber'";
$alreadyexisits=odbc_exec($connection,$alreadyexisitssql);

if(odbc_fetch_row($alreadyexisits)){
//retrun a value that says the data already exists
}
else{
    $addpiosql = "INSERT INTO [ScopesheetPIO] ([ScopesheetID], [PIONumber]) VALUES ('$scopesheetid', '$pionumber')";
    $addpioresult=odbc_exec($connection,$addpiosql);
//retrun a vlaue that the data was added
}

What I really want is a way to pass a value from the PHP script back into the Jquery

Answer 1

I would modify your jQuery to the following:

$.post('addpio.php', { ... }, function(data) {
    if (data.result) {
        $('#pioslist').append(...);
    }
}, 'json');

In your PHP file, use this when the data is inserted:

echo json_encode(array(
    'result' => TRUE
));

Use this when the data already exists:

echo json_encode(array(
    'result' => FALSE
));

Answer 2

Build an array in PHP and output it as JSON. Then inspect the returned JSON in your script.

if(odbc_fetch_row($alreadyexists)){
    // Return a value that says the data already exists
    $result = array(
        "error" => "Data already exists"
    );
} else {
    // Database stuff goes here...
    // Return a value that the data was added
    $result = array(
        "success" => 1
    );
}
echo json_encode($result);

JavaScript $.post callback:

function(data) {
    if(data.success) {
        // Append element to HTML
    } else {
        // An error occurred, inform the user
        // Don't actually use alert(), this is just for demonstrating purposes
        alert(data.error);
    }
}

Later on, you can then create more complex responses with extra data by simply adding them to the $result array and reading them from data in your JavaScript.

Answer 3

Write anything in your PHP that you'll test in your callback function :

PHP

if(odbc_fetch_row($alreadyexisits)){
 echo "ko";
}
else{
    $addpiosql = "INSERT INTO [ScopesheetPIO] ([ScopesheetID], [PIONumber]) VALUES ('$scopesheetid', '$pionumber')";
    $addpioresult=odbc_exec($connection,$addpiosql);
    echo "ok";
}

JS

$.post("addpio.php", { scopesheetid: scopesheetidvalue, pionumber: piovalue },function(data){
    if( data == 'ok' ) {
        $('#pioslist').append("<li><input class='removepio' type='submit' value='"+piovalue+"' /><span class='listitem'>PIO "+piovalue+"</span></li>");
    }
});  

Answer 4

You can easily pass data from a script to jQuery. IMO I think its best to use JSON as its much more neater.

PHP (for example):
$arrayOfData=array("val1"=>"value","val2"=>"value");

//encode it
$arrayOfData=json_encode($arrayOfData);

//print it on screen
echo $arrayOfData;

And then get it in jQuery using the .getJSON.

$.getJSON("url_of_php_fle",function(myData){

//now use myData as the array:
alert(myData.val1);//which will give you "value" as what you set in PHP

}):

It really is that easy.