Build adapters to compare array structures from different sources

M66 2025-06-06

In PHP, array_diff_uassoc is a function for comparing two or more arrays. It will not only compare the values of the array, but also their keys. The core function of this function is to return all key-value pairs that exist in the first array but are not in other arrays, and will compare the keys through user-defined callback functions. By appropriately using array_diff_uassoc , we can build an adapter to compare array structures from different sources.

This article will show you how to use the array_diff_uassoc function to build an adapter to compare data structure differences from different sources, especially when you need to compare key names based on certain business rules.

1. Basic concepts

Definition of array_diff_uassoc function

 array_diff_uassoc ( array $array1 , array $array2 , callable $key_compare_func ) : array

$array1 : The first array.
$array2 : The second array.
$key_compare_func : A callback function used to compare two keys.

This function returns key-value pairs that exist in $array1 and are not in $array2 . The comparison key is done through the $key_compare_func callback function.

The role of key_compare_func

The callback function key_compare_func must accept two parameters, namely the keys of two arrays. It should return:

An integer less than 0: if the first key is less than the second key;
Returns 0: If the two keys are equal;
An integer greater than 0: If the first key is greater than the second key.

This comparison method is very suitable for use when you need to compare keys according to specific rules.

2. Ideas for building adapters

We will use a simple example to show how to build an adapter with array_diff_uassoc and compare array structures from different sources.

Suppose we have two different data sources, each containing an array of key-value pairs, and we need to compare these arrays to find out the differences between them.

Sample code

 <?php

// The first array（source1）
$array1 = [
    'id' => 1,
    'name' => 'Alice',
    'email' => 'alice@m66.net',
    'age' => 28
];

// The second array（source2）
$array2 = [
    'id' => 2,
    'name' => 'Bob',
    'email' => 'bob@m66.net',
    'address' => '123 Main St'
];

// Custom key comparison function
function key_compare($key1, $key2) {
    // If the two keys are equal，return 0
    return strcmp($key1, $key2);
}

// use array_diff_uassoc Compare arrays
$diff = array_diff_uassoc($array1, $array2, 'key_compare');

// Output difference
print_r($diff);

?>

Code parsing:

Array definition : We define two arrays $array1 and $array2 , which represent data from different sources. These arrays have different structures (such as different key names and data).
Custom key comparison function : key_compare is the callback function we defined, which uses strcmp() to compare two keys. If the two keys are equal, return 0; otherwise, return the corresponding comparison result.
Call array_diff_uassoc : We compare $array1 and $array2 through the array_diff_uassoc function. At this time, it will find out the different parts of the keys in the two arrays based on the customized key comparison function.
Output Difference : print_r($diff) outputs the difference part in the two arrays.

Output example:

 Array
(
    [email] => alice@m66.net
    [age] => 28
)

Explain the output:

The above output shows that there are two keys ( email and age ) in $array1 , which do not exist in $array2 . This is the difference part of what we call the two arrays.

3. Application scenarios of adapters

Use array_diff_uassoc to build adapters, which are especially suitable for the following scenarios:

Multi-source data comparison : When processing data from multiple sources, you may encounter different structures. Using array_diff_uassoc , you can flexibly compare these data sources and find out their differences.
Complex data structure conversion : Sometimes we need to convert data in different formats into a unified format according to business rules. array_diff_uassoc can help us identify mismatched parts and then make adjustments.
Profile comparison : When comparing configuration files for different environments, array_diff_uassoc can help us easily identify differences between different configurations, especially when the key name rules for these configurations are different.

4. Summary

array_diff_uassoc is a powerful PHP function that can help us use custom key comparison functions to accurately judge the differences between them when comparing arrays from different sources. In practical applications, we can implement the adapter mode through it to adapt to diverse data structures and business needs.

With the above example, we can see how to compare array structures using array_diff_uassoc and implement flexible adapter functionality based on custom rules. I hope this article can help you better understand and apply this function!

array_diff_uassoc