


How do I install the dependencies listed in my composer.json file? (composer install)
Jul 16, 2025 am 01:34 AMThe most direct way to install dependencies is to run composer install. The specific steps are as follows: 1. Make sure that Composer is installed, and you can check the version through composer --version; 2. Enter the project root directory and execute composer install. The command will install dependencies based on composer.json and composer.lock, generate automatic loading configurations and store them in vendor/ directory; 3. You can use --no-dev to skip development dependencies, -o optimization class loader, --prefer-dist to priority download zip files, etc. to enhance control; 4. If the installation fails, common reasons include incompatible PHP version, lack of extensions, network problems or insufficient permissions, and you can troubleshoot and solve them based on the error message.
The most direct way to install the dependencies listed in the composer.json
file is to run the composer install
command. This command will download and set all required packages based on your composer.json
and optional composer.lock
files.
Make sure you have Composer installed
Before executing any Composer commands, you need to make sure that Composer is already installed on your system. You can check whether it is installed by following the command:
composer --version
If you see an output similar to Composer version 2.xx
, it means that it has been installed. If not, you can download and install it from getcomposer.org .
Run composer install
in the project directory
Go to the root directory of your project (that is, the directory where composer.json
is located), and run:
composer install
This command does several things:
- Read dependencies defined in
composer.json
- If
composer.lock
exists, install it accurately according to the version in the file - If there is no
composer.lock
, the appropriate version will be parsed according tocomposer.json
and acomposer.lock
will be generated. - Download all dependencies into
vendor/
directory - Automatic load configuration write to
vendor/autoload.php
Tip: If you are running for the first time, or if you don't have
composer.lock
, Composer will automatically create it. This file is important and is recommended to submit it to Git so that other developers can install completely consistent dependent versions.
Common options when installing dependencies
Sometimes you may need some extra control, and the following are a few commonly used parameters:
--no-dev
Skip the dependencies required by the development environment (such as PHPUnit and PHPStan and other tools that are only used in the development stage).--optimize-autoloader
or-o
Optimize class loaders to improve performance, and are recommended to use in production environments.--prefer-dist
Preferring to downloading packaged.zip
files from remotely, rather than cloning Git repositories, is usually faster.--ignore-platform-reqs
Ignore platform requirements (such as PHP versions or extensions) for certain special scenarios, but are not recommended for regular use.
For example, when deploying to a production environment, you can run it like this:
composer install --no-dev -o
What to do if you encounter problems?
If the installation fails, common reasons are:
- PHP version does not meet the requirements
- Missing the necessary PHP extensions (such as
ext-curl
,ext-mbstring
) - The network connection problem causes the package to be downloaded
- Insufficient permissions, cannot be written to
vendor/
orcomposer.lock
Checking the error message can usually locate the problem. For example, if the prompt is missing a certain extension, it can be solved by installing the corresponding extension; if it is a network problem, you can try to use a domestic mirror source.
Basically that's it. As long as the command runs through, the dependency will be installed.
The above is the detailed content of How do I install the dependencies listed in my composer.json file? (composer install). For more information, please follow other related articles on the PHP Chinese website!

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