Problem with list() function in PHP

Question

I've written the code below:

$release_id = intval(filter_var($_GET["rid"],FILTER_SANITIZE_STRING));
$query = "select * from press_releases where id = {$release_id}";

$result = $db->query($query);
$row = $result->fetch_assoc();

list($id, $short_description, $description, $created_date) = $row;

$db->close();

and I am using the variables such as $description, $short_description inside of the html tags but nothing shows. If I use the code below which is same except for the list() function:

$release_id = intval(filter_var($_GET["rid"],FILTER_SANITIZE_STRING));
$query = "select * from press_releases where id = {$release_id}";

$result = $db->query($query);
$row = $result->fetch_assoc();

$id = $row["id"];
$short_description = $row["short_description"];
$description = stripslashes(html_entity_decode($row["description"]));
$created_date = $row["created_date"];

$db->close();

it works perfectly. Basically list() function cannot assign the values coming from the $row array.

I don't understand why?

user456814 · Accepted Answer · 2011-07-02 21:03:34Z

5

According to the PHP docs for list():

list() only works on numerical arrays and assumes the numerical indices start at 0.

answered Jul 2, 2011 at 21:03

user456814

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2 Comments

Tarik Over a year ago

This makes sense now. It is already said on the documentation but I couldn't see it: php.net/manual/en/function.list.php

Felix Kling Over a year ago

@Braveyard: In addition, list() assigns the values in reverse order (see the warning further below).

Brad · Accepted Answer · 2011-07-02 21:03:01Z

4

I don't believe the list() function works with associative arrays. Try fetching your query results normally (numerical indices) and see if that resolves the issue for you.

answered Jul 2, 2011 at 21:03

Brad

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Comments

mario · Accepted Answer · 2011-07-02 21:24:47Z

3

You want to use extract() instead of list().

This is the one that's appropriate for associative results. And you shouldn't use it with SELECT * but a concrete list of SELECT varname1,varname2,varname3 so you don't get unexpected local variables.

_{It's also possible to use extract(array_intersect_key(..)) to get a filtered list of variables to be extracted, but that's overkill for database result sets that you can control anyway.}

answered Jul 2, 2011 at 21:24

mario

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1 Comment

Tarik Over a year ago

I really like this version as well.. Thanks a lot. extract and array_values would be great solutions...

Jani Hartikainen · Accepted Answer · 2011-07-02 21:05:14Z

2

A rather easy solution to this is as follows:

list($id, $short_description, $description, $created_date) = array_values($row);

Or simply don't fetch as assoc, but as a normal array.

I must say I don't really recommend doing this. Since your SQL query is fetching with *, it will break very easily - Let's say for whatever reason one of the columns gets shuffled around so it appears at some other position in the table. Bam.

Assuming you were to define each column separately in your query, then it would be fine.

answered Jul 2, 2011 at 21:05

Jani Hartikainen

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1 Comment

Felix Kling Over a year ago

In addition, you have to reverse the list of variables because list assignes the values from right to left.

CrayonViolent · Accepted Answer · 2011-07-02 21:04:20Z

1

My guess is that list() expects a numerically indexed array. Try using $row = $result->fetch_row(); instead

answered Jul 2, 2011 at 21:04

CrayonViolent

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Comments

Amber · Accepted Answer · 2011-07-02 21:04:29Z

1

list() expects an indexed array, not an associative one. Try using fetch_row().

answered Jul 2, 2011 at 21:04

Amber

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Comments

Emre Yazici · Accepted Answer · 2011-07-02 21:04:37Z

1

Use array_values like this:

list($id, $short_description, $description, $created_date) = array_values($row);

Read the comment by kevin in here on php.net.

answered Jul 2, 2011 at 21:04

Emre Yazici

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Comments

Emil Vikström · Accepted Answer · 2011-07-02 21:05:26Z

1

list does only work with numerically indexed arrays. Switch fetch_assoc to fetch_row or use array_values on $row before the assignment:

$row = $result->fetch_row();

or

list($id, $short_description, $description, $created_date) = array_values($row);

answered Jul 2, 2011 at 21:05

Emil Vikström

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Kerrek SB · Accepted Answer · 2011-07-02 21:09:28Z

1

Use fetch_row rather than fetch_assoc, see the example. ~~Associative~~Hash arrays have no well-defined element order!

edited Jul 2, 2011 at 21:09

answered Jul 2, 2011 at 21:03

Kerrek SB

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4 Comments

Kerrek SB Over a year ago

@Felix: Sorry, I meant "hash containers". Of course ordered associative containers like C++'s std::set do have an order -- but the order is not that of insertion, rather than of key value. I'm not sure about PHP, but I thought that associative arrays were hash-based, like std::unordered_map...

Felix Kling Over a year ago

Uhm, I don't know about C++. But in PHP there is actually only one type of array and the elements are ordered (insertion order), no matter whether the keys are numeric or strings.

Kerrek SB Over a year ago

@Felix: I see -- is this actually guaranteed? (What an expensive data structure that must be...) If it were, then the list construction should really work for those arrays, too.

Felix Kling Over a year ago

Yes it is. And yes it should work, but apparently it does not, for whatever reason.

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