Check if array doesn't have a key and create it dynamically - php

Question

I need to check if the keys of an array match an array of keys, and if they don't match then they need to be created. While I managed to create the check I still need to return all keys that don't match in the in_array condition so that they can be added to the original array. How can I achieve this?
My current code:
$new_value = ['id','name','age'];
$keys = ['id','name','age','sex','height','weight'];
foreach($new_value as $new_value){
if(!in_array($new_value, $keys )){
$new_value["{$key}"] = '';
}
}
The desired result would be:
Array pre processing:
'id' => 1,
'name' => 'Ed',
'age' => 15,
Array post processing:
'id' => 1,
'name' => 'Ed',
'age' => 15,
'sex' => '',
'height' => '',
'weight' => '',

Answer 1

So, there are a couple of things here.
// When you are running through your foreach, you don't want to overwrite your
// array variable with the value, which is what is happening. Switch this to `new_values` (plural)
$new_values = ['id','name','age'];
$keys = ['id','name', 'age','sex','height','weight'];
// Since $keys is your desired structure, we want to loop through $key rather than $new_values, and add any missing keys to the $new_values
foreach($keys as $key){
// We want to check if $new_values has all the $keys (you were checking if $keys had all of $new_values, which it does already
if(!in_array($key, $new_values )){
// Since $key is already a string, we don't need to place it in quotes, just put the variable directly into the array as a new array item (because you are using an array of strings, the keys will be numerical)
$new_values[] = $key
}
}
If you are looking for a keyed array, so that you can get the value of $new_values['name'], then you will need to set your arrays up differently and do your checks differently. You can also use $keys to hold a default value.
// Set the keys for your array, instead of having an array of strings that is keyed numerically
$new_values = ['id' => 'user_id','name' => 'user name','age' => 'user age'];
$keys = ['id' => 'default_value','name' => 'default_value', 'age' => 'default_value','sex' => 'default_value','height' => 'default_value','weight' => 'default_value'];
// Here we'll get the key and value of each item in the $keys array
foreach($keys as $key => $default) {
// Check if the array key exists in new values and if not, set it to the predefined default value
if(!array_key_exists($key, $new_values) {
$new_values[$key] = $default;
}
}
EDIT
As per one of the comments on the answer, you could further simplify this with array_merge. If you want to throw an error or do something special on each field, you could use the loop. If you just want to fill in the blanks, it would work like:
// Set the keys for your array, instead of having an array of strings that is keyed numerically
$new_values = ['id' => 'user_id','name' => 'user name','age' => 'user age'];
$keys = ['id' => 'default_value','name' => 'default_value', 'age' => 'default_value','sex' => 'default_value','height' => 'default_value','weight' => 'default_value'];
// If you aren't going to be using the original $new_values array for anything, you can just overwrite it.
// As stated in the comment below, $new_values should be the second value, keys that are in both arrays will be overwritten by what's in the second array.
$new_values = array_merge($keys, $new_values);
// If you will be using the original $new_values array later in the code, you can set the output to a new variable
$filled_values = array_merge($keys, $new_values);

Answer 2

I'm not sure, but you can try next code:
<?php
$data = [
"id" => 1,
"name" => "Ed",
"age" => 15,
];
$keys = ["id", "name", "age", "sex", "height", "weight"];
$result = array_reduce(
$keys,
function ($data, $key) {
if (!isset($data[$key])) $data[$key] = '';
return $data;
},
$data
);
var_export($result);
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