Convert PostgreSQL array to PHP array - php

Question

I have trouble reading Postgresql arrays in PHP. I have tried explode(), but this breaks arrays containing commas in strings, and str_getcsv() but it's also no good as PostgreSQL doesn't quote the Japanese strings.
Not working:
explode(',', trim($pgArray['key'], '{}'));
str_getcsv( trim($pgArray['key'], '{}') );
Example:
// print_r() on PostgreSQL returned data: Array ( [strings] => {または, "some string without a comma", "a string, with a comma"} )
// Output: Array ( [0] => または [1] => "some string without a comma" [2] => "a string [3] => with a comma" )
explode(',', trim($pgArray['strings'], '{}'));
// Output: Array ( [0] => [1] => some string without a comma [2] => a string, with a comma )
print_r(str_getcsv( trim($pgArray['strings'], '{}') ));

Answer 1

If you have PostgreSQL 9.2 you can do something like this:
SELECT array_to_json(pg_array_result) AS new_name FROM tbl1;
The result will return the array as JSON
Then on the php side issue:
$array = json_decode($returned_field);
You can also convert back. Here are the JSON functions page

Answer 2

As neither of these solutions work with multidimentional arrays, so I offer here my recursive solution that works with arrays of any complexity:
function pg_array_parse($s, $start = 0, &$end = null)
{
if (empty($s) || $s[0] != '{') return null;
$return = array();
$string = false;
$quote='';
$len = strlen($s);
$v = '';
for ($i = $start + 1; $i < $len; $i++) {
$ch = $s[$i];
if (!$string && $ch == '}') {
if ($v !== '' || !empty($return)) {
$return[] = $v;
}
$end = $i;
break;
} elseif (!$string && $ch == '{') {
$v = pg_array_parse($s, $i, $i);
} elseif (!$string && $ch == ','){
$return[] = $v;
$v = '';
} elseif (!$string && ($ch == '"' || $ch == "'")) {
$string = true;
$quote = $ch;
} elseif ($string && $ch == $quote && $s[$i - 1] == "\\") {
$v = substr($v, 0, -1) . $ch;
} elseif ($string && $ch == $quote && $s[$i - 1] != "\\") {
$string = false;
} else {
$v .= $ch;
}
}
return $return;
}
I haven't tested it too much, but looks like it works.
Here you have my tests with results:
var_export(pg_array_parse('{1,2,3,4,5}'));echo "\n";
/*
array (
0 => '1',
1 => '2',
2 => '3',
3 => '4',
4 => '5',
)
*/
var_export(pg_array_parse('{{1,2},{3,4},{5}}'));echo "\n";
/*
array (
0 =>
array (
0 => '1',
1 => '2',
),
1 =>
array (
0 => '3',
1 => '4',
),
2 =>
array (
0 => '5',
),
)
*/
var_export(pg_array_parse('{dfasdf,"qw,,e{q\"we",\'qrer\'}'));echo "\n";
/*
array (
0 => 'dfasdf',
1 => 'qw,,e{q"we',
2 => 'qrer',
)
*/
var_export(pg_array_parse('{,}'));echo "\n";
/*
array (
0 => '',
1 => '',
)
*/
var_export(pg_array_parse('{}'));echo "\n";
/*
array (
)
*/
var_export(pg_array_parse(null));echo "\n";
// NULL
var_export(pg_array_parse(''));echo "\n";
// NULL
P.S.: I know this is a very old post, but I couldn't find any solution for postgresql pre 9.2

Answer 3

Reliable function to parse PostgreSQL (one-dimensional) array literal into PHP array, using regular expressions:
function pg_array_parse($literal)
{
if ($literal == '') return;
preg_match_all('/(?<=^\{|,)(([^,"{]*)|\s*"((?:[^"\\\\]|\\\\(?:.|[0-9]+|x[0-9a-f]+))*)"\s*)(,|(?<!^\{)(?=\}$))/i', $literal, $matches, PREG_SET_ORDER);
$values = [];
foreach ($matches as $match) {
$values[] = $match[3] != '' ? stripcslashes($match[3]) : (strtolower($match[2]) == 'null' ? null : $match[2]);
}
return $values;
}
print_r(pg_array_parse('{blah,blah blah,123,,"blah \\"\\\\ ,{\100\x40\t\daő\ő",NULL}'));
// Array
// (
// [0] => blah
// [1] => blah blah
// [2] => 123
// [3] =>
// [4] => blah "\ ,{## daőő
// [5] =>
// )
var_dump(pg_array_parse('{,}'));
// array(2) {
// [0] =>
// string(0) ""
// [1] =>
// string(0) ""
// }
print_r(pg_array_parse('{}'));
var_dump(pg_array_parse(null));
var_dump(pg_array_parse(''));
// Array
// (
// )
// NULL
// NULL
print_r(pg_array_parse('{または, "some string without a comma", "a string, with a comma"}'));
// Array
// (
// [0] => または
// [1] => some string without a comma
// [2] => a string, with a comma
// )

Answer 4

If you can foresee what kind text data you can expect in this field, you can use array_to_string function. It's available in 9.1
E.g. I exactly know that my array field labes will never have symbol '\n'. So I convert array labes into string using function array_to_string
SELECT
...
array_to_string( labels, chr(10) ) as labes
FROM
...
Now I can split this string using PHP function explode:
$phpLabels = explode( $pgLabes, "\n" );
You can use any sequence of characters to separate elements of array.
SQL:
SELECT
array_to_string( labels, '<--###DELIMITER###-->' ) as labes
PHP:
$phpLabels = explode( '<--###DELIMITER###-->', $pgLabes );

Answer 5

As #Kelt mentioned:
Postgresql arrays look like this: {1,2,3,4}
You can just simply replace first { and last } with [ and ]
respectively and then json_decode that.
But his solution works only for one-dimensional arrays.
Here the solution either for one-dimensional and multidimensional arrays:
$postgresArray = '{{1,2},{3,4}}';
$phpArray = json_decode(str_replace(['{', '}'], ['[', ']'], $postgresArray)); // [[1,2],[3,4]]
To cast back:
$phpArray=[[1,2],[3,4]];
$postgresArray=str_replace(['[', ']'], ['{', '}'], json_encode($phpArray));

Answer 6

Based on the answers in the thread i created two simple php functions that can be of use:
private function pgArray_decode(string $pgArray){
return explode(',', trim($pgArray, '{}'));
}
private function pgArray_encode(array $array){
$jsonArray = json_encode($array, true);
$jsonArray = str_replace('[','{',$jsonArray);
$jsonArray = str_replace(']','}',$jsonArray);
return $jsonArray;
}

Answer 7

I tried the array_to_json answer, but unfortunalety this results in an unknown function error.
Using the dbal query builder on a postgres 9.2 database with something like ->addSelect('array_agg(a.name) as account_name'), I got as result a string like { "name 1", "name 2", "name 3" }
There are only quotes around the array parts if they contain special characters like whitespace or punctuation.
So if there are quotes, I make the string a valid json string and then use the build-in parse json function. Otherwise I use explode.
$data = str_replace(array("\r\n", "\r", "\n"), "", trim($postgresArray,'{}'));
if (strpos($data, '"') === 0) {
$data = '[' . $data . ']';
$result = json_decode($data);
} else {
$result = explode(',', $data);
}

Answer 8

If you have control of the query that's hitting the database, why don't you just use unnest() to get the results as rows instead of Postgres-arrays? From there, you can natively get a PHP-array.
$result = pg_query('SELECT unnest(myArrayColumn) FROM someTable;');
if ( $result === false ) {
throw new Exception("Something went wrong.");
}
$array = pg_fetch_all($result);
This sidesteps the overhead and maintenance-issues you'd incur by trying to convert the array's string-representation yourself.

Answer 9

I can see you are using explode(',', trim($pgArray, '{}'));
But explode is used to Split a string by string (and you are supplying it an array!!). something like ..
$string = "A string, with, commas";
$arr = explode(',', $string);
What are you trying to do with array? if you want to concatenate have a look on implode
OR not sure if it is possible for you to specify the delimiter other than a comma? array_to_string(anyarray, text)

Answer 10

Postgresql arrays look like this: {1,2,3,4}
You can just simply replace first { and last } with [ and ] respectively and then json_decode that.
$x = '{1,2,3,4}';
$y = json_decode('[' . substr($x, 1, -1) . ']'); // [1, 2, 3, 4]
To cast back the other way would be mirror opposite:
$y = [1, 2, 3, 4];
$x = '{' . substr(json_encode($y), 1, -1) . '}';

Answer 11

A simple and fast function for converting deep PostgreSQL array string to JSON string without using pg connection.
function pgToArray(string $subject) : array
{
if ($subject === '{}') {
return array();
}
$matches = null;
// find all elements;
// quoted: {"1{\"23\"},abc"}
// unquoted: {abc,123.5,TRUE,true}
// and empty elements {,,}
preg_match_all( '/\"((?<=\\\\).|[^\"])*\"|[^,{}]+|(?={[,}])|(?=,[,}])/', $subject,$matches,PREG_OFFSET_CAPTURE);
$subject = str_replace(["{","}"],["[","]"],$subject); // converting delimiters to JSON
$matches = array_reverse($matches[0]);
foreach ($matches as $match) {
$item = trim($match[0]);
$replace = null;
if ((strpos($item,"{") !== false) || (strpos($item,"}") !== false)) {
// restoring replaced '{' and '}' inside string
$replace = $match[0];
} elseif (in_array($item,["NULL","TRUE","FALSE"])) {
$replace = strtolower($item);
} elseif ($item === "" || ($item[0] !== '"' && !in_array($item,["null","true","false"]) && !is_float($item))) {
$replace = '"' . $item . '"'; // adding quotes to string element
}
if ($replace) { // concatenate modified element instead of old element
$subject = substr($subject, 0, $match[1]) . $replace . substr($subject, $match[1] + strlen($match[0]));
}
}
return json_decode($subject, true);
}