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What You’ll Learn

  • Understanding the three code snippet types
  • Using the updated code editor
  • Selecting Sites, Tags, or Clients for snippets
  • Running and saving code snippets
  • Reviewing saved snippets and target counts
  • Removing snippets from child sites
  • Recovering from bad snippets
  • Useful wp-config.php snippets
Extension Add-on - This add-on provides standalone functionality within MainWP Dashboard. No third-party plugins required.
The MainWP Code Snippets Extension is a simple way to add code snippets to your child sites from one centralized location. A code snippet is a small chunk of PHP code that can be sent to your child sites, saved on your child sites, or written to wp-config.php, depending on the snippet type. Sometimes snippets contain full functions; other times, they modify an existing function.
This tool is recommended for advanced users only. We only recommend utilizing it if you are an experienced PHP coder.

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Code Snippet Types

The MainWP Code Snippets Extension allows you to process code in three ways:

Execute on Site

This type of snippet saves the snippet in the selected child site database and executes it when the child site loads. Use this option to make persistent changes to selected child sites. For example, use it to customize the admin footer across different sites in your network.
This type of snippet runs on selected child sites and displays the returned output in the Console. It is useful for queries that return information, such as the published post count for each selected site. This type is not saved on child sites.
This type of snippet writes the snippet to the selected child site’s wp-config.php file. Use it only for configuration constants and code that belongs in wp-config.php, such as increasing the WordPress memory limit, blocking external requests, or disabling WP-Cron.
MainWP is not responsible for the code that you run on your sites. Use this tool with extreme care and at your own risk. Run any code on a test site before releasing it on live sites. If you execute a bad code snippet and crash your child sites, you need to remove the code snippet from your sites.

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Code Editor and Validation

The snippet editor uses CodeMirror 6 and includes:
  • Code folding controls and fold keyboard shortcuts
  • Autocompletion
  • Automatic bracket closing
  • Bracket matching
  • Tab indentation with a four-space tab size
  • Line wrapping and active line highlighting
Before a snippet is saved, run, or pushed to child sites, the extension checks the PHP syntax. If the parser finds a syntax error, the extension stops the process and shows the error message.
Syntax validation helps catch malformed PHP before it reaches your sites. It does not verify that the code is logically safe, that called functions exist, or that the snippet will behave as intended in every site environment.
The validator also rejects top-level namespace, declare, and use statements because snippets are executed as raw PHP code, not as standalone PHP files.

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Select Sites, Tags, or Clients

Use the Select Sites panel to choose where a snippet applies. The selector includes tabs for Sites, Tags, and Clients. Each saved snippet stores one targeting mode at a time:
  • Sites - Save the selected child site IDs.
  • Tags - Save the selected tag IDs.
  • Clients - Save the selected client IDs.
If you switch from one targeting mode to another, the extension saves the targets from the active selection mode only.

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Snippets Table

The Snippets tab lists saved snippets in a table with these columns:
  • Snippet - Shows the snippet title and description together.
  • Type - Shows a colored label for Execute, Return, or wp-config.php.
  • Target - Shows a count with an icon for Sites, Tags, or Clients.
  • Last Edited - Shows the relative edit time, with the exact date available on hover.
  • Actions - Open or delete the snippet.

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Remove a Code Snippet From a Broken Site

Code snippets can be removed directly from the database. To do this:
1

Log in to your cPanel, locate phpMyAdmin, and open your site database

2

Locate and open the site's options table

The default table name is wp_options, but the prefix may be different on your site.
3

Remove the Code Snippets option rows

Locate and remove the option_name = mainwp_ext_snippets_enabled row, or the option_name = mainwp_ext_code_snippets row.
This will remove all database-saved code snippets that were applied using our Code Snippets extension. If you use bad snippets that are saved to wp-config.php, the file will need to be edited manually.

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Run a Code Snippet

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Run a New Code Snippet

1

Log in to your MainWP Dashboard

2

Go to MainWP > Add-ons > Administrative > Code Snippets

Open the New Snippet tab.
3

Enter a Snippet Title

4

Enter a Snippet Description (optional)

5

Select the snippet type

Choose Execute on Site, Return Info, or Add to wp-config.php.
6

Select Sites, Tags, or Clients

Use the site selector to choose the Sites, Tags, or Clients where you want to run the snippet.
7

Add your Code Snippet in the code editor

Add your Code Snippet in the code editor MainWP Code Snippets > Code Editor
8

Click the Run Snippet button

The extension saves the snippet, validates the PHP syntax, and opens the Console. For Return Info snippets, the Console shows returned output for each selected child site. For Execute on Site and Add to wp-config.php snippets, the Console shows the processing status.MainWP Code Snippets editor with Execute on Site selected and the Run Snippet button highlighted

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Run a Saved Code Snippet

1

Log in to your MainWP Dashboard

2

Go to MainWP > Add-ons > Administrative > Code Snippets

Open the Snippets tab.
3

Open the snippet that you want to run

Click the snippet title or the green action button in the table.MainWP Code Snippets table with the saved snippet action button highlighted
4

Review the snippet type and selected targets

Confirm the snippet type and the selected Sites, Tags, or Clients.
5

Click the Run Snippet button

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Save a Code Snippet

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Save a New Code Snippet

1

Log in to your MainWP Dashboard

2

Go to MainWP > Add-ons > Administrative > Code Snippets

Open the New Snippet tab.
3

Enter a Snippet Title

4

Enter a Snippet Description (optional)

5

Select the snippet type

Choose Execute on Site, Return Info, or Add to wp-config.php.
6

Select Sites, Tags, or Clients

Use the site selector to save the snippet target selection. The snippet stores only the active target mode: Sites, Tags, or Clients.
7

Add your Code Snippet in the code editor

Add your Code Snippet in the code editor MainWP Code Snippets > Code Editor
8

Click the Save button

The extension saves the snippet in MainWP Dashboard without pushing it to child sites.

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Edit a Saved Code Snippet

1

Log in to your MainWP Dashboard

2

Go to MainWP > Add-ons > Administrative > Code Snippets

Open the Snippets tab.
3

Locate the Code Snippet that you want to edit

4

Open the saved snippet

Click the snippet title or the green action button in the table.
5

Edit the snippet details

Update the title, description, snippet type, target selection, or code.
6

Click the Save button

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Remove a Code Snippet From Child Sites

1

Log in to your MainWP Dashboard

2

Go to MainWP > Add-ons > Administrative > Code Snippets

Open the Snippets tab.
3

Locate the Code Snippet that you want to remove from your child sites

4

Open the saved snippet

5

Update the selected targets

Unselect the child sites, tags, or clients where you want to remove the snippet.
6

Click the Run Snippet button

This process removes the existing saved copy from child sites and then re-adds it only to the currently selected targets. This method is recommended when you want to keep the snippet in the Snippets list so it can be used again later. To remove the snippet from all child sites but keep it saved in MainWP Dashboard, clear the selected targets and click Run Snippet.

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Console Process Status

When you click Run Snippet, the Console opens and shows the current process status. Depending on the snippet type and whether the snippet already exists on child sites, you may see steps such as checking existing snippets, saving snippets on child sites, and executing snippets on child sites. The Console also shows progress counts, site-level status icons, returned output for Return Info snippets, and a Stop Process button for stopping queued or in-progress processing.

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Useful Code Snippets

MainWP is not responsible for the code that you run on your sites. Use this tool with extreme care and at your own risk. It is recommended that you run any code on a test site before releasing it on live sites. In case you damage your site by using a bad code snippet, read Remove a Code Snippet From a Broken Site to see how to fix it.

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Delete rows in the wp_mainwp_stream_meta and wp_mainwp_stream tables

This can be useful if the wp_mainwp_stream_meta and wp_mainwp_stream tables have grown large in size. To prevent them from growing this large in the future, consider lowering the number of days for which the records are kept. NOTE: This will delete all records in these two tables, which means that the Pro Reports reports will not have any information about events prior to this deletion. When running the script, make sure to select Return Info. 
global $wpdb;
$wpdb->query( "TRUNCATE TABLE {$wpdb->mainwp_stream}" );
$wpdb->query( "TRUNCATE TABLE {$wpdb->mainwp_streammeta}" );

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Change the value of “Keep Records for” in MainWP Child Reports plugin

Code Snippets console output for the Return Info option When running the script, make sure to select Return Info. 
global $wpdb;

$option = get_option( 'wp_mainwp_stream' );

if ( $option && isset( $option['general_records_ttl'] ) ) {
    $option['general_records_ttl'] = 31; // New desired value (e.g., 30 days)
    update_option( 'wp_mainwp_stream', $option );
}

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Disable theme, plugin editor and plugin, core updates

This snippet goes to the wp-config.php file of your child sites. Be sure to select Add to wp-config.php when using the code snippet. 
define('DISALLOW_FILE_EDIT',true); // theme, plugin
define('DISALLOW_FILE_MODS',true); // core, plugin

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Disable CRON job feature

This snippet goes to the wp-config.php file of your site. Be sure to select Add to wp-config.php when using the code snippet. 
define('DISABLE_WP_CRON', true);

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Set auto-save interval

This snippet goes to the wp-config.php file of your site. Be sure to select Add to wp-config.php when using the code snippet. 
define('AUTOSAVE_INTERVAL', 200);

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Block external requests

This snippet goes to the wp-config.php file of your site. Be sure to select Add to wp-config.php when using the code snippet. 
define('WP_HTTP_BLOCK_EXTERNAL', true);
This snippet blocks outbound HTTP requests. It can also prevent WordPress, plugin, and theme update checks unless you allow the required hosts.

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Increase WordPress memory limit

This snippet goes to the wp-config.php file of your site. Be sure to select Add to wp-config.php when using the code snippet. 
define('WP_MEMORY_LIMIT', '95M');

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Enable Debug Mode

This snippet goes to the wp-config.php file of your site. Be sure to select Add to wp-config.php when using the code snippet. 
define( 'WP_DEBUG', true );

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Disable All Core Updates

This snippet goes to the wp-config.php file of your site. Be sure to select Add to wp-config.php when using the code snippet. 
define( 'WP_AUTO_UPDATE_CORE', false );

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Protect WordPress against malicious URL requests

Use the Execute on Site option when running this snippet. The extension saves this snippet in the child site’s database and runs it when the child site loads. 
global $user_ID; if($user_ID) {
        if(!current_user_can('administrator')) {
                if (strlen($_SERVER['REQUEST_URI']) > 255 ||
                        stripos($_SERVER['REQUEST_URI'], "eval(") ||
                        stripos($_SERVER['REQUEST_URI'], "CONCAT") ||
                        stripos($_SERVER['REQUEST_URI'], "UNION+SELECT") ||
                        stripos($_SERVER['REQUEST_URI'], "base64")) {
                                @header("HTTP/1.1 414 Request-URI Too Long");
                                @header("Status: 414 Request-URI Too Long");
                                @header("Connection: Close");
                                @exit;
        }
    }
}
Source: WPSnip.com