Getting values from a just created array - php

Question

I have this function that creates an array of values:
function getPostInfo($query, $fields, $type, $limit, $since, $until, $lang, $stopwords, $identifier) {
$url = file_get_contents('https://graph.facebook.com/search?q='.spaces($query).'&fields='.$fields.'&limit='.$limit.'&until='.$until);
$j = json_decode($url);
foreach($j->data as $v) {
if ($v->type == $type) {
$author_id = $v->from->id;
$original_id = $v->id;
$post_url = getPostUrl($original_id, $author_id);
//$description = stopWords($v->message);
$description = $v->message;
$pub_date = $v->created_time;
$post[] = array(
'author_id' => $author_id,
'orginal_id' => $original_id,
'post_url' => $post_url,
'descritpion' => $description,
'pub_date' => $pub_date
);
}
}
return $post;
}
When I call this function like this:
$post = getPostInfo($query, $fields, $type, $limit, $since, $until, $lang, $stopwords, $identifier);
echo var_dump($post);
The array returns correctly.
But If I try to search for a specific value of the array like this:
echo var_dump($post['author_id']);
it always returns NULL.
What is wrong in my code?
Thank you for the help.

Answer 1

I believe if you change
$post[] = array(
to
$post = array(
it should fix the issue.
Can you display the result of your var_dump($post)?

Answer 2

The assignment in the function is wrong. You need to use this code (strip the [] parentesys)
$post = array(
'author_id' => $author_id,
'orginal_id' => $original_id,
'post_url' => $post_url,
'descritpion' => $description,
'pub_date' => $pub_date
);
or access the index you need by
$post[0]['author_id']
In this situation you should rely on var_dump or var_export to investigate on how your data structure is layed down. I prefer the second one as is output is similar to
the code needed to obtain the data and it is easier to find errors.
In the manual, you will see that var_dump returns void and if you try to echo its result you will not obtain what expected
echo var_dump($post['author_id']);
strip the echo and you will get fine with you output (use var_export or ob_start if you need to get a string with the output).
EDIT
As in the comment, the $post variable is an array of arrays, the above notes are still valid as you need to access the various author_id index prefixing the index of the array containing it. If you need to get all the id of the authors in a place then you can resort to array map:
$authors = array_map(function($x){return $x['author_id'];},$post);
If you where was trying to obtains something else you should better explain what the expected result was.

Answer 3

Like Eineki says you're trying to access an element of the array that doesn't exists. If you do a var_dump on the $post variable like this:
var_dump($post);
You should see that the $post array is actually a numerical array starting at [0] and each item includes a sub-array containing your data.
What you've created is a two dimensional array, an array of arrays, one array for each item in your $j->data array.
You can iterate through the array like this:
foreach ($post as $key => $value)
{
var_dump($value);
var_dump($value['author_id'];
}

Answer 4

Let's make this really fun and easy.
function getPostInfo($query, $fields, $type, $limit, $since, $until, $lang, $stopwords, $identifier) {
//your code
}
}
return (object)$post;
}
then when you access your returned object it's just
$post->author_id;
this is just for fun but it works well. Converts an array into a standard object. :)
ok let's get serious ;)
Initialize the array before the foreach statement ($posts = array()), then assign the variables to the array keys ($post['key'] = $value) then assign each set of array keys to the array ($posts[] = $post). I hope this helps.
function getPostInfo($query, $fields, $type, $limit, $since, $until, $lang, $stopwords, $identifier) {
$url = file_get_contents('https://graph.facebook.com/search?q='.spaces($query).'&fields='.$fields.'&limit='.$limit.'&until='.$until);
$j = json_decode($url);
$posts = array(); //initialize array here
foreach($j->data as $v) {
if ($v->type == $type) {
//create variables
$author_id = $v->from->id;
$original_id = $v->id;
$post_url = getPostUrl($original_id, $author_id);
//$description = stopWords($v->message);
$description = $v->message;
$pub_date = $v->created_time;
//asign values to array keys
$post['author_id'] = $author_id;
$post['orginal_id'] = $original_id;
$post['post_url'] = $post_url;
$post['descritpion']= $description;
$post['pub_date'] = $pub_date;
//asign $post to the $posts array to create an array of $post(s)
$posts[] = $post;
}
}
return $posts;
}
I think this might help accomplish what you want.
the following code is the reference used. It is from the examples from the Array section in the PHP manual.
<?php
// This:
$a = array( 'color' => 'red',
'taste' => 'sweet',
'shape' => 'round',
'name' => 'apple',
4 // key will be 0
);
$b = array('a', 'b', 'c');
// . . .is completely equivalent with this:
$a = array();
$a['color'] = 'red';
$a['taste'] = 'sweet';
$a['shape'] = 'round';
$a['name'] = 'apple';
$a[] = 4; // key will be 0
$b = array();
$b[] = 'a';
$b[] = 'b';
$b[] = 'c';
// After the above code is executed, $a will be the array
// array('color' => 'red', 'taste' => 'sweet', 'shape' => 'round',
// 'name' => 'apple', 0 => 4), and $b will be the array
// array(0 => 'a', 1 => 'b', 2 => 'c'), or simply array('a', 'b', 'c').
?>