Prefixing array keys with a string (:) in PHP

Question

Quick one; I know a solution, but I'm looking for something more elegant if it exists.

I'm using PDO for prepeared statements:

$sql = "INSERT INTO my_table (foo, bar, baz) VALUES (:foo, :bar, :baz)";

$source->execute($sql, array(
    ':foo' => $foo,
    ':bar' => $bar,
    ':baz' => $baz,
));

This is fine, but I want to pass in a previously created array, however the keys contained aren't prefixed by the colon (:), and I figure there must be an elegant way to take:

$array = array(
    'foo' => 'some',
    'bar' => 'random',
    'baz' => 'value',
);

And translate it into:

$array = array(
    ':foo' => 'some',
    ':bar' => 'random',
    ':baz' => 'value',
);

Without doing:

$temp = array();
foreach($array as $key => $value){
    $temp[':' . $key] = $value;
}
$array = $temp;

I've browsed the PHP docs, but I can't find a function (or sequence of) that suits the purpose.

Any ideas?

Addendum

Leaving the accepted answer, but +1 @chim for his clever 1-liner; solves the X in my XY problem. Reformatted solution:

$format = ':%s';
$values = array_flip(array_map(function ($key) use($format) {
    return sprintf($format, $key);
}, array_flip($values)));

Wrapped in a function, perhaps array_keys_format(array $array, $format)

AFAIK PDO's execute() will work correctly even if the keys aren't prefixed by a colon. — NullUserException
– NullUserException, Commented Oct 1, 2011 at 8:16
@NullUserException - I thought that too, but its kicking back invalid SQL state, complaining about the query parameters (other than the colon prefix, it would run given its unnecessary) — Dan Lugg
– Dan Lugg, Commented Oct 1, 2011 at 8:18
@Bracketworks: what php version are you using? Tested with 5.2.17 and 5.3.8 here, and working as expected. — Decent Dabbler
– Decent Dabbler, Commented Oct 1, 2011 at 8:28
@fireeyedboy - Yea, sleep deprivation != working. 5.3.6, and yea, its working :) Sorry NullUser, you were right also. — Dan Lugg
– Dan Lugg, Commented Oct 1, 2011 at 8:30

Decent Dabbler · Accepted Answer · 2011-10-01 08:29:46Z

8

$source->execute($sql, array(
    'foo' => $foo,
    'bar' => $bar,
    'baz' => $baz
));

This is presuming the above calls PDOStatement::execute() under the hood, with the above array as its argument.¹

:)

^{1) Tested with version 5.2.17 and 5.3.8 here, and working as expected.}

edited Oct 1, 2011 at 8:29

answered Oct 1, 2011 at 8:18

Decent Dabbler

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1 Comment

Dan Lugg Over a year ago

You know, perhaps it's late, but its working now. I'm going to bed, but first I'm accepting this answer because it fixes the problem, just as NullUser had said too. +1's all around. Thanks @fireeyedboy!

lsl · Accepted Answer · 2011-10-01 08:34:46Z

3

It has already been answered but this is what I came up with anyway.

$arr = array('foo'=>1,'bar'=>2);

$arr = array_flip($arr);

array_walk($arr,create_function('&$v,$k', '$v = ":$v";'));

$arr = array_flip($arr);

print_r($arr);

answered Oct 1, 2011 at 8:34

lsl

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Comments

0xDEADBEEF · Accepted Answer · 2011-10-01 08:21:07Z

2

use the php map-function: http://php.net/manual/en/function.array-map.php

function reduce($key)
{
if(strpos($key,":")===0)
return substr($key,1);
return $key;
}

$array = array_map("reduce",$array);

answered Oct 1, 2011 at 8:21

0xDEADBEEF

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2 Comments

chim Over a year ago

Doesn't work array_map doesn't affect the keys of an array, and the reduce function above doesn't prepend a : to the beginning of anything.

chim Over a year ago

What the function does do is remove a leading : from the values in the array.

chim · Accepted Answer · 2013-04-11 08:23:59Z

2

One liner...

$array = array('test'=>'55','yest'=>'66');

$array = array_flip(array_map(function($v){return ':' . $v;},array_flip($array)));

// array(':test'=>'55',':yest'=>'66');

However this isn't safe as array_flip relies on all values being unique.

So one of the looping solutions is probably the best, or alternatively array_keys with array_combine.

edited Apr 11, 2013 at 8:23

answered Apr 9, 2013 at 15:51

chim

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1 Comment

mickmackusa Over a year ago

Flipping must not be trusted if the values in the array may collide after being coalesced to a scalar-type key.

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