How to get inner array value using PHP without key - php

Question

In my php file I get string which looks like [["category_id","=","3"],["price","<","40"]] from Android. I will use that for select query. But how can I get each item from it?
Here my code:
<?php
$filter = $_POST[‘filter’];
$filter_text = “”;
foreach($filter as $filter_item){
foreach($filter_item as list($column, $equality, $value)){
$filter_text .= "product." . $column . $equality. "'" . $value . "' AND ";
}
}
...
?>

Answer 1

Looks like you're constructing a WHERE clause to an SQL query. Here's a clue on how to build the string, but you should be using prepared statements instead of injecting user input directly into your query! Also, you don't actually need to nest a foreach, as is demonstrated below. See comments for explanation.
To use prepared statements (and please do!), you can substitute the variables in the ANDed conditions with "product.? ? ?";. Then use PDOStatement::bindValue(). Other flavors of parameter binding are available.
<?php
// Your input array.
$filters = [["category_id","=","3"],["price","<","40"]];
// Your question is unclear on this, but if your $_POST['filter'] is not actually an array, but a JSON string, then you may try this:
$filters = json_decode($_POST['filter'], TRUE); // TRUE to decode to associative array.
// $where holds each WHERE condition, so you can perform a clean string glue with implode().
// In your current string concatenation, additional conditions are required, or the query
// will fail due to an errant trailing AND if none are following.
$where = [];
// $filterText will hold this part of your WHERE clause. Consider renaming it to something
// more descriptive, like $whereSql.
$filterText = '';
foreach ($filters as [$key, $comparisonOperator, $value])
$where[] = "product.$key $comparisonOperator $value";
// Glue each condition with as many ANDs are necessary.
$filterText .= implode(' AND ', $where);
echo $filterText;
// Outputs: product.category_id = 3 AND product.price < 40
UPDATE: Your question is a little unclear on this, so I've added something that you can try. This updated answer now assumes your input isn't actually an array, but a JSON string.

Answer 2

You can use implode and some looping
$filter = isset($_POST['filter']) ? $_POST['filter'] : '';
$arr = json_decode($filter,true);
foreach($arr as $k => $v) {
$query['q'][] = [
'column' => 'product.' . $v[0],
'equality' => $v[1],
'value' => $v[2]
];
}
$filter = array();
foreach($query as $q) {
foreach($q as $k) {
$filter[]= sprintf("%s %s %s", $k['column'],$k['equality'],$k['value']);
}
}
$query = implode(' AND ',$filter);
echo $query;
// product.category_id = 3 AND product.price < 40
Warning: You are wide open to SQL Injections and should use parameterized prepared statements instead of manually building your queries. They are provided by PDO or by MySQLi. Never trust any kind of input! Even when your queries are executed only by trusted users, you are still in risk of corrupting your data. Escaping is not enough!
-Dharman