Using WordPress ‘allow_subdirectory_install()’ PHP function

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The allow_subdirectory_install() WordPress PHP function checks if a subdirectory installation is allowed in a multisite network setup.

Usage

Use the function allow_subdirectory_install() in your code as follows:

if ( allow_subdirectory_install() ) {
    echo "Subdirectory installation is allowed.";
} else {
    echo "Subdirectory installation is not allowed.";
}

The function returns true if a subdirectory installation is allowed, and false otherwise.

Parameters

  • This function does not take any parameters.

More information

See WordPress Developer Resources: allow_subdirectory_install()
This function is used in the WordPress core to manage multisite networks. It’s an important part of WordPress’ multisite feature, allowing you to control the type of site installation.

Examples

Checking if Subdirectory Install is Allowed

// Use the function to check if a subdirectory install is allowed
if ( allow_subdirectory_install() ) {
    echo "Proceed with subdirectory installation.";
} else {
    echo "Cannot proceed, subdirectory installation is not allowed.";
}

This code checks whether subdirectory installation is allowed and outputs a message accordingly.

Conditional Actions Based on Subdirectory Installation

// Perform action based on the allowance of subdirectory install
if ( allow_subdirectory_install() ) {
    // code to execute if subdirectory install is allowed
    install_subdirectory();
} else {
    // alternative code to execute if not allowed
    echo "Please choose another installation method.";
}

In this example, we use the function to decide the course of action in our program. If a subdirectory installation is allowed, the function install_subdirectory() is called. Otherwise, a message is displayed to the user.

Setting Variables Based on Subdirectory Installation

// Set a variable based on the allowance of subdirectory install
$canInstall = allow_subdirectory_install();

// Use the variable later in your code
if ($canInstall) {
    // code to execute if subdirectory install is allowed
    install_subdirectory();
} else {
    // alternative code to execute if not allowed
    echo "Please choose another installation method.";
}

This example demonstrates how to store the result of the function in a variable for later use in your program.

Using Subdirectory Installation Status in a Function

function manage_installation() {
    if ( allow_subdirectory_install() ) {
        // code to execute if subdirectory install is allowed
        install_subdirectory();
    } else {
        // alternative code to execute if not allowed
        echo "Please choose another installation method.";
    }
}

// Call the function
manage_installation();

In this example, we use the function within another function to manage the installation process.

Handling Installation Exceptions

// Handle exception if subdirectory installation is not allowed
try {
    if ( !allow_subdirectory_install() ) {
        throw new Exception('Subdirectory installation is not allowed.');
    }

    // code to execute if subdirectory install is allowed
    install_subdirectory();
} catch (Exception $e) {
    echo 'Caught exception: ',  $e->getMessage(), "\n";
}

In this case, we use the function in combination with a try-catch block to handle exceptions. If a subdirectory installation is not allowed, an exception is thrown and caught.