Assigning a javascript array with PHP/Postgresql query values in a loop

Question

So, I have a postgresql database and I'm querying a particular column's values and assigning each value to a javascript array. Now I have a javascript function which outputs this data on a map. When i test the array manually (Entering the respective array index one by one), it returns the output perfectly alright. But in a loop (When i want to output all at once), i can only see the first element's output. The rest of the array is simply ignored or there's an error. I don't understand where the mistake is. Here's the code:

<script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?key=AIzaSyC0HZ81Ea8Jy8fJ6zm6_uvPp8UhLg5mczo&sensor=true"></script>
<script type="text/javascript" src="GeoJSON.js"></script>
<script type="text/javascript" src="polygon.js"></script>


<script type="text/javascript">

var geojson_Polygon = new Array();

function kaushik()
{

    <?php
        require("header.php");

        $connection = pg_connect($full);

        if(!$connection)
        {
            pg_close($connection);

        }

        $result = pg_query($connection, "SELECT ogc_fid, ST_AsGeoJSON(wkb_geometry), name FROM features");
        if (!$result) 
        {
            exit;
        }

        $i = 0;         
        while ($row = pg_fetch_row($result)) 
        {   
            echo "\n";
            echo "geojson_Polygon[$i] = $row[1];";
            echo "\n";
            echo "\n";
            $i++;
        }

    ?>

    for (var j=0; j<317; j++)
    {
        showFeature(geojson_Polygon[j]);
    }


}
</script>

I don't know, what you want to do... You are generating PHP code with JS? This couldn't work i think, because PHP is a server side language and will be rendered on the server. JS runs on the client and will be rendered after PHP. — Tobi
– Tobi, Commented Apr 20, 2012 at 8:15
I'm sure it works. Cause the first iteration of the javascript loop is successful. Its only the successive iterations that fail. — KaushikTD
– KaushikTD, Commented Apr 20, 2012 at 8:28
@Tobi PHP is processed on the server and then sent to the client, while javascript is processed on the client. Basically writing PHP code that echoes javascript or writing javascript code is exactly the same thing. — Nicola Peluchetti
– Nicola Peluchetti, Commented Apr 20, 2012 at 8:32

tereško · Accepted Answer · 2012-04-20 08:41:43Z

2

If what you want to do is build a JS array , then just do:

<script type="text/javascript">
   var data = [ <?php

      // --- snip
      $first = true;
      while ($row = pg_fetch_row($result)) 
      {
          if ( $first )
          {
             $first = false;
          }else{
             echo ',';
          }
          echo $row[$i]
      }
      // ---- snip

   ?> ];
</script>

answered Apr 20, 2012 at 8:41

tereško

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4 Comments

KaushikTD Over a year ago

The array builds fine. Now, when i try to output the array is the problem. I don't know where I'm going wrong there..

tereško Over a year ago

@KaushikTD , well . what is the output you get ?

KaushikTD Over a year ago

snipplr.com/view/64689/javascript-array-assigned-using-php-loop

KaushikTD Over a year ago

What I meant was that the array builds fine with the code I gave. I believe there's some problem when pulling out all the data at one shot.

Nicola Peluchetti · Accepted Answer · 2012-04-20 08:29:24Z

0

i think you should do

 while ($row = pg_fetch_row($result)) 
    {   
        echo "\n";
        echo "geojson_Polygon[$i] = $row[$i];";
        echo "\n";
        echo "\n";
        $i++;
    }

otherwise the value is always the same

edited Apr 20, 2012 at 8:29

answered Apr 20, 2012 at 8:13

Nicola Peluchetti

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6 Comments

KaushikTD Over a year ago

okay so showFeature(); is a javascript function found in polygon.js which plots the polygon on a map (after converting from GeoJSON to Google Maps Api format). This is successful. the conversion and plotting. Please see that the for loop falls only after the php end tag. I'm using php and javascript. Php to query the db. And I'm using echo to output javascript.

Nicola Peluchetti Over a year ago

@KaushikTD maybe you should change $row[1] to $row[$i] otherwise in the loop $row[1] is always the same. Anyway can you post the generated html?

KaushikTD Over a year ago

in PostGresql row[1] refers to the first column and not the first row! The php loop automatically queries all the data in that column row[1]. If I did what you've mentioned, I'll be getting results from all the columns, and not the particular column i want data out of.

Nicola Peluchetti Over a year ago

@KaushikTD yep you are right, i'll delete this, can you please post the generated javascript?

KaushikTD Over a year ago

The generated javascript is pretty long, about 317 data points, with each point holding co-ordinates of a polygon in GeoJSON format. I'll link it to you. Just give me a sec.

|

Richard Huxton · Accepted Answer · 2012-04-20 09:49:18Z

0

Just read the rows into a php array and then assign it as json.

<script>
...
var geojson_Polygon = <?php echo json_encode($all_rows); ?>;
....

answered Apr 20, 2012 at 9:49

Richard Huxton

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