wpmu_validate_blog_signup($blog_id, $blog_title, $user = ”)

Summary: Checks a requested new blog’s information against a series of validation rules.

Detail: This function checks that a new blog meets a number of validation rules before proceeding on to create the blog. The rules include making sure the new blog’s name isn’t on the banned list, checking that there is a name, that it is alphanumerical, that it’s long enough, etc. You can pretty much read through this function if you want to check the rules as they are.

You could also use this function to impose your own rules, if you’d prefer hacking the core to creating a plugin.

install_blog_defaults($blog_id, $user_id)

Summary: Installs the default values of a WP blog during the creation of a new blog

Details: This function does a lot, and depending on how you want your blogs setup, may be useful to modify. It sets up default values for such things as the blogroll, the first post, the first comment, the default category. Of these options, only the default post can be set in Blog Options, so for finer tuning of the end-user experience, editing this file might be helpful.

install_blog($blog_id, $blog_title = ”)

Summary: Creates a new blog with the id $blog_id and the title $blog_title

Detail: This is a very complex function that involves calling the upgrade-functions.php file and using a bunch of it’s functions to complete its task. This is definitely a function which – in the absence of a specific need – is better off left on its own and accessed through the API.

get_blog_post( $blog_id, $post_id )

Summary: Retrieves the post $post_id from the blog $blog_id

Detail: This simple function checks the wp_cache for the blog post in question, and in its absence, queries the database directly for the whole thing. Returns an object with all the values contained in the database.

get_blog_option( $blog_id, $setting, $default=’na’ )

Summary: Function returns the value of the specified option $setting.

Detail: This is a surprisingly complex function that returns the value of the specified options $setting. It first checks for the existence of a wp-cache value, and if none exists, queries the database.

The rest of the function complexity is simply to make sure that a properly-validated URL is returned if the requested option is the site URL.

get_blogaddress_by_id($blog_id)

Uses the get_blog_details() function to return the address of a blog given it’s blog ID.

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