PHP AJAX HTML: changing unique table data in foreach loop - php

Question

I'm new to PHP and Ajax. I am trying to create a table of object data where I can select the displayed data based on a <select><option>... form.
I have a PHTML template which looks like the following:
<?php
$content = "";
// creates data selector
$content .= "
<form id = select_data>
<select id = data_selection>
<option value = data1>Data 1</option>
<option value = data2>Data 2</option>
<option value = data3>Data 3</option>
<option value = data4>Data 4</option>
</select>
<input id = selected_data type=submit />
</form>";
// creates table header
$content .= "
<tr>
<th>Data</th>
</tr>";
$array_ids = array(1, 2, 3); // etc, array of object id's
foreach ($array_ids as $array_id) {
$object = // instantiate object by array_id, pseudocode
$object_data = $object->getData('default-data'); // get default data to display
// create table item for each object
$content .= "
<tr>
<td><p>$object_data</p></td>
</tr>";
}
print $content;
?>
This prints out the table content, loads objects by their id, then gets and displays default data within the <p> tag.
And then I have some Javascript which looks like the following:
<script src="//code.jquery.com/jquery-1.11.3.min.js"></script>
<script>
$(document).ready(function(){
$('#select_data').on('submit', function(e){ // get selected data type
e.preventDefault();
var data_selected = $("#data_selection :selected").val(); // create var to pass to ajax
$.ajax({
type: "POST",
url: 'post.php',
data: {data_selected: data_selected},
success: function(data){
$("p").html(data); // replace all <p> tag content with data
}
});
});
});
</script>
This Javascript gets the selected data type, creates a variable out of it to pass on to the ajax which then calls post.php, which looks like the following:
<?php
$attribute = false;
if (isset($_POST['data_selected'])){
$data = $_POST['data_selected']; // assigns variable out of ajax data
$object = //instantiate object, again pseudocode
$object_data = $object->getData($data); // get new data to replace into the ```<p>``` tag
echo $object_data;
}
?>
The problem is that the Javascript that I have changes every single <p> tag to the last data iterated by the foreach loop because each <p> tag is not uniquely identified and the Ajax does not update the data based on a unique identifier, such as maybe the $array_id. Which brings me to my attempted solution.
I tried to identify each <p> tag with the following:
<td><p id = $array_id>$object_data</p></td>
And then creating a new Javascript variable out of the array ID:
var p_tag_id = <?php echo $array_id; ?>;
And finally making the Ajax success function target element ID's based on var p_tag_id:
$("#" + p_tag_id).html(data);
While this does not change all the <p> tags like previously, it only changes the final <p> tag and leaves all instances before it unchanged because the Javascript is not iterating over each <p> tag, or because the foreach loop does not call the Javascript as a function for each $array_id.
How can I rewrite this code so that the Ajax updates the data of each table item uniquely instead of updating them all with the same data? Is there a better way to approach this problem?

Answer 1

You need a way to identify the table row containing the <p> tag you wish to update, and perhaps the value attribute of the SELECT element could help.
You can get the number of the clicked option from your data_selected variable by using slice to strip-off the last character (i.e. the number):
var num = data_selected.slice(-1) - 1;
(Subtract 1 because the table rows are zero-indexed)
Then, in the AJAX code block's success function:
$('table tr').each(function(i,v){
if (i == num){
$(v).find('td').find('p').html(data);
}
});
The above grabs all the table rows (as a collection) and loops through them one-by-one. In the function, i is the index number of the row and v is the row itself. Index numbers begin at zero, which is why you earlier subtracted 1 from the (for eg) data3 [3] value, leaving num == 2. When you find the right row number, use .find() to find the <td> in that row, and then the <p> in that <td> and Bob's yer uncle.
I haven't tested the above code so there could be bugs in the example, but off-the-cuff this approach should work.

Answer 2

I figured out a solution. I assigned the $array_id to each <p> tag after all in order to identify them uniquely:
<td><p id = $array_id>$object_data</p></td>
Then I looped over all the <p> tags and assigned the $array_id of this <p> tag to a variable like so:
$("p").each(function() {
var array_id = $(this).attr("id");
And finally I made the Ajax success target elements based on their ID:
$("#" + array_id ).html(data);
Here is the full Javascript code for anybody who is interested. Hopefully this helps someone else out!
<script>
$(document).ready(function(){
$('#select_data').on('submit', function(e){
e.preventDefault();
var data_selected = $("#data_selection :selected").val();
$("p").each(function() {
var array_id = $(this).attr("id");
$.ajax({
type: "POST",
url: 'post.php',
data: {data_selected: data_selected, array_id: array_id},
success: function(data){
$("#" + array_id).html(data);
}
});
});
});
});
</script>