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up vote 91 down vote favorite
23

I'm looking for the name of the PHP function to build a query string from an array of key value pairs. Please note, I am looking for the built in PHP function to do this, not a homebrew one (that's all a google search seems to return). There is one, I just can't remember its name or find it on php.net. IIRC its name isn't that intuitive.

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5 Answers 5

up vote 172 down vote accepted

You're looking for http_build_query().

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1  
Yeah, that's the one. –  Robin Barnes Dec 30 '08 at 17:00
    
Wish I'd known about that function a long time ago. Heh. –  ceejayoz Dec 30 '08 at 17:17
1  
Never knew about this. Super! –  Carpetsmoker Mar 15 '11 at 23:27
3  
+1 because I found it here faster than I could find it on php.net –  TecBrat Jun 5 '13 at 15:47
1  
Be careful with this function! It will omit any key-value pair where the value is NULL. echo http_build_query(array("foo"=>"bar","bar"=>null)) will produce only foo=bar –  cb0 Aug 13 at 13:06
up vote 11 down vote

Here's a simple php4-friendly implementation:

/**
* Builds an http query string.
* @param array $query  // of key value pairs to be used in the query
* @return string       // http query string.
**/
function build_http_query( $query ){

    $query_array = array();

    foreach( $query as $key => $key_value ){

        $query_array[] = urlencode( $key ) . '=' . urlencode( $key_value );

    }

    return implode( '&', $query_array );

}
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I guess you didn't see the accepted answer? –  John Conde May 13 '11 at 20:09
23  
this is a php4 version. –  thatjuan May 13 '11 at 21:08
1  
When doing its decoding, PHP appears to percent-decode the key as well. Possibly worth doing that here? –  cloudfeet Aug 1 '13 at 15:38
    
@cloudfeet seems reasonable to do so. Thanks for pointing it out. –  thatjuan Aug 1 '13 at 17:35
    
+1 for implode!! –  Wolter Hellmund May 8 at 23:47
up vote 0 down vote

I'm not aware of a builtin function, but there is the PECL class http://uk.php.net/manual/en/class.httpquerystring.php

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up vote 0 down vote

Implode will combine an array into a string for you, but to make an SQL query out a kay/value pair you'll have to write your own function.

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Tried that but it won't work. I'm trying to build an http query string which requires both the keys and the values from the array, implode can't do this. –  Robin Barnes Dec 30 '08 at 17:00
1  
I see, wasn't sure if you meant an SQL query string or a http query string. –  Click Upvote Dec 30 '08 at 21:05
up vote 0 down vote

but for inverse this work, you can use :

void parse_str(str $input, array $output);
//for example:
$str = "first=value&arr[]=foo+bar&arr[]=baz";
parse_str($str);
echo $first;  // value
echo $arr[0]; // foo bar
echo $arr[1]; // baz

parse_str($str, $output);
echo $output['first'];  // value
echo $output['arr'][0]; // foo bar
echo $output['arr'][1]; // baz

Good luck.

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