How to Use array_fill_keys to Create an Initially Empty User Permission Table? A Practical PHP Guide

gitbox 2025-08-27

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<p>echo <span><span class="hljs-string">"<p>In PHP development, we often need to initialize a permissions table for a group of users or roles. Suppose we have a user list where each user’s initial permissions are empty (or set to null by default). How can we efficiently generate such an array? PHP provides a very convenient function: <code>array_fill_keys

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2. Example: Creating a User Permission Table

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Let’s say we have the following users:

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$users = ['alice', 'bob', 'charlie'];

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We want to initialize an empty permissions array for each user:

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$permissions = array_fill_keys($users, []);

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After execution, the contents of $permissions are as follows:

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3. Dynamically Assigning Initial Permissions

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If we want each user’s initial permissions to be a default value instead of an empty array, for example, granting a 'read' permission:

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$permissions = array_fill_keys($users, ['read']);

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The result will be:

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4. Summary

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With array_fill_keys, we can quickly create an array where the keys are usernames (or role names) and the values are initial permissions. This saves us from the hassle of manually assigning values through loops, making it highly suitable for initializing user permission tables.

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array_fill_keys