Title: Help using a variable in a function parameter
Last modified: June 21, 2019

---

# Help using a variable in a function parameter

 *  Resolved [OthelloBloke](https://wordpress.org/support/users/othellobloke/)
 * (@othellobloke)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/)
 * I have the following code in a plugin:
 *     ```
       if( $var != '' && !is_user_logged_in() ) {
       	if( is_child( $var ) ) {
       		auth_redirect();
       	}
       }
       ```
   
 * $var is functioning as intended on the page and I use it elsewhere in the template,
   but it’s not working when used as a parameter for the is_child() function.
 * If I put the ID number manually as the parameter.. it works perfectly.
 * Can someone help me figure out why please?
    -  This topic was modified 6 years, 11 months ago by [OthelloBloke](https://wordpress.org/support/users/othellobloke/).

Viewing 15 replies - 1 through 15 (of 19 total)

1 [2](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/page/2/?output_format=md)
[→](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/page/2/?output_format=md)

 *  [catacaustic](https://wordpress.org/support/users/catacaustic/)
 * (@catacaustic)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11658956)
 * Start off with some standarddebigging. Something like this will let you see exactly
   what is going on with that code.
 *     ```
       if( $var != '' && !is_user_logged_in() ) {
               echo "<p>var: '".$var."'</p>";
       	if( is_child( $var ) ) {
       		auth_redirect();
       	}
       }
       ```
   
 * If that isn’t correct, wrk backwards until you find out where the problem is.
 *  Thread Starter [OthelloBloke](https://wordpress.org/support/users/othellobloke/)
 * (@othellobloke)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11658966)
 * I already did that. It’s echoing the page ID number that it’s supposed to.
 * But it doesn’t work when I put the variable as the parameter 🙁
 *  [catacaustic](https://wordpress.org/support/users/catacaustic/)
 * (@catacaustic)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659001)
 * The you should add the echo line in s the first line of the is_child() function
   and see what that’s telling you that it’s getting. If that’s the same, then look
   further into that function.
 * is_child() isn’t part of the WordPress core, so there’s no way for anyone here
   to say how it works unless we can see the code for it 🙂
 *  Thread Starter [OthelloBloke](https://wordpress.org/support/users/othellobloke/)
 * (@othellobloke)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659003)
 * It’s not echoing anything 🙁 I’m stuck. Here’s the is_child function:
 *     ```
       <?php
   
       if( !function_exists( "is_child" ) ) {
   
       	function is_child( $ofParent, $doRecursive = true ) {
   
       		global $wpdb;
       		$allCats = array();
   
       		// Turn title or slug into ID if needed.
       		if( !is_int( $ofParent ) ) {
       			if( is_page() )
       				# Different handling for Pages
       				$getID = $wpdb->get_results("
       					SELECT	ID as cat_ID
       					FROM	{$wpdb->posts}
       					WHERE	post_title = '{$ofParent}'
       					OR		post_name = '{$ofParent}'
       					LIMIT	0,1
       				");
       			else
       				# Get catID
       				$getID = $wpdb->get_results("
       					SELECT	cat_ID
       					FROM	{$wpdb->terms}
       //					FROM	{$wpdb->categories}
       					WHERE	cat_name = '{$ofParent}'
       					OR		category_nicename = '{$ofParent}'
       					LIMIT	0,1
       				");
   
       			if( !$getID )
       				# Not found.
       				return false;
       			else {
       				# Found.
       				$ofParent = $getID[0]->cat_ID;
       				unset( $getID );
       			}
       		}
   
       		// Everyone's a sub zero.
       		if( $ofParent == 0 && $doRecursive )
       			return true;
   
       		// Now let's break it down to categories (or pages).
       		if( is_page() ) {
       			global $post;
       			$allCats[] = $post->ID;
       		} elseif( is_single() ) {
       			$getCats = get_the_category();
       			foreach( $getCats as $getCat )
       				$allCats[] = $getCat->cat_ID;
       			unset( $getCats );
       		} elseif( is_category ) {
       			global $cat;
       			$allCats[] = $cat;
       		}
   
       		// Already a match? Would save processing time.
       		if( in_array( $ofParent, $allCats ) )
       			return true;
   
       		// Post without recursive search ends here.
       		if( ( is_single() ) && !$doRecursive )
       			return false;
   
       		// Otherwise, let's do some genealogy.
       		while( count( $allCats ) != 0 ) {
       			if( in_array( $ofParent, $allCats ) )
       				return true;
       			else 
       				$allCats = 
       					is_child_getParents( $allCats );
       		}
   
       		// Still here? Then nothing has been found.
       		return false;
   
       	}
       }
   
       if( !function_exists( "is_child_getParents" ) ) {
   
       	function is_child_getParents( $fromChilds ) {
   
       		// As there's only get_category_parents which isn't useful 
       		// for fetching parental data, we'll have to query this
       		// directly to the DB.
       		global $wpdb;
   
       		$fromChilds = implode( ", ", $fromChilds );
       		if( !$fromChilds ) return array();
   
       		$getParents = 
       			( is_page() )
       			?	# Pages
       				$wpdb->get_results("
       					SELECT	post_parent AS category_parent
       					FROM	{$wpdb->posts}
       					WHERE	ID IN ({$fromChilds})
       				")
       			: 	# Posts / Categories
       				$wpdb->get_results("
       					SELECT	category_parent
       //					FROM	{$wpdb->categories}
       					FROM	{$wpdb->terms}
       					WHERE	cat_ID IN ({$fromChilds})
       				");
   
       		foreach( $getParents as $getParent )
       			if( $getParent->category_parent != 0 )
       				$allParents[] = $getParent->category_parent;
   
       		return $allParents;
   
       	}
       }
       ```
   
 *  [catacaustic](https://wordpress.org/support/users/catacaustic/)
 * (@catacaustic)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659011)
 * What does this do?
 *     ```
       if( !function_exists( "is_child" ) ) {
   
       	function is_child( $ofParent, $doRecursive = true ) {
       echo "<p>ofParent: '".$ofParent."'</p>";
       		global $wpdb;
                       .....
   
               }
       }
       else {
       echo "<p>is_child() already exists!</p>";
       }
       ```
   
 *  Thread Starter [OthelloBloke](https://wordpress.org/support/users/othellobloke/)
 * (@othellobloke)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659018)
 * is_child already exists.
 *  [catacaustic](https://wordpress.org/support/users/catacaustic/)
 * (@catacaustic)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659020)
 * Then that’s your problem. Your version of is_child() is not being used because
   it’s already defined somewhere else before yours is loaded. You’ll need to find
   waht is already there, and see if it’s compatible. If not you can also change
   the name of your function to something unique that doesn’t interfere with anything
   else.
 *  Thread Starter [OthelloBloke](https://wordpress.org/support/users/othellobloke/)
 * (@othellobloke)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659023)
 * Yeah it’s being defined in the same plugin.
 *  [catacaustic](https://wordpress.org/support/users/catacaustic/)
 * (@catacaustic)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659024)
 * It can’t work like that. You can not ever have two functions called the same 
   thing. You will need to change the name of one of them to something unqiue.
 *  Thread Starter [OthelloBloke](https://wordpress.org/support/users/othellobloke/)
 * (@othellobloke)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659028)
 * No I mean it’s only defined in one place in the plugin… and then I use the is_child
   function later on in the plugin in a difference place.
 *  [catacaustic](https://wordpress.org/support/users/catacaustic/)
 * (@catacaustic)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659033)
 * That’s not how it works. It may only be defined in one place in your plugin, 
   but from the results of your own debugging it’s already been defined by something
   else before the system gets to your plugins code. That’s why the echo of “already
   exists” shows. If you remove the if(function_exists()) call you’ll see the error
   and where it is defined.
 * But, again… you only need to change the name of that function to soemthing unique
   it will work.
 *  Thread Starter [OthelloBloke](https://wordpress.org/support/users/othellobloke/)
 * (@othellobloke)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659034)
 * So why does it work if I replace my original code with:
 * if( !is_user_logged_in() && is_child(232) ) { auth_redirect(); }
 *  [catacaustic](https://wordpress.org/support/users/catacaustic/)
 * (@catacaustic)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659036)
 * But is that calling _your_ is_child() function, or _the other_ is_child() function?
   I’ll bet it’s the other one. And I can’t tell you that because I don’t know what
   the other is_chld() function does. Again, that’s added somewhere else.
 *  Thread Starter [OthelloBloke](https://wordpress.org/support/users/othellobloke/)
 * (@othellobloke)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659040)
 * I just went through the ENTIRE plugin, and the ONLY place is_child is used or
   mentioned is here:
 *     ```
       <?php
   
       if( !function_exists( "is_child" ) ) {
   
       	function is_child( $ofParent, $doRecursive = true ) {
   
       		global $wpdb;
       		$allCats = array();
   
       		// Turn title or slug into ID if needed.
       		if( !is_int( $ofParent ) ) {
       			if( is_page() )
       				# Different handling for Pages
       				$getID = $wpdb->get_results("
       					SELECT	ID as cat_ID
       					FROM	{$wpdb->posts}
       					WHERE	post_title = '{$ofParent}'
       					OR		post_name = '{$ofParent}'
       					LIMIT	0,1
       				");
       			else
       				# Get catID
       				$getID = $wpdb->get_results("
       					SELECT	cat_ID
       					FROM	{$wpdb->terms}
       //					FROM	{$wpdb->categories}
       					WHERE	cat_name = '{$ofParent}'
       					OR		category_nicename = '{$ofParent}'
       					LIMIT	0,1
       				");
   
       			if( !$getID )
       				# Not found.
       				return false;
       			else {
       				# Found.
       				$ofParent = $getID[0]->cat_ID;
       				unset( $getID );
       			}
       		}
   
       		// Everyone's a sub zero.
       		if( $ofParent == 0 && $doRecursive )
       			return true;
   
       		// Now let's break it down to categories (or pages).
       		if( is_page() ) {
       			global $post;
       			$allCats[] = $post->ID;
       		} elseif( is_single() ) {
       			$getCats = get_the_category();
       			foreach( $getCats as $getCat )
       				$allCats[] = $getCat->cat_ID;
       			unset( $getCats );
       		} elseif( is_category ) {
       			global $cat;
       			$allCats[] = $cat;
       		}
   
       		// Already a match? Would save processing time.
       		if( in_array( $ofParent, $allCats ) )
       			return true;
   
       		// Post without recursive search ends here.
       		if( ( is_single() ) && !$doRecursive )
       			return false;
   
       		// Otherwise, let's do some genealogy.
       		while( count( $allCats ) != 0 ) {
       			if( in_array( $ofParent, $allCats ) )
       				return true;
       			else 
       				$allCats = 
       					is_child_getParents( $allCats );
       		}
   
       		// Still here? Then nothing has been found.
       		return false;
   
       	}
       }
   
       if( !function_exists( "is_child_getParents" ) ) {
   
       	function is_child_getParents( $fromChilds ) {
   
       		// As there's only get_category_parents which isn't useful 
       		// for fetching parental data, we'll have to query this
       		// directly to the DB.
       		global $wpdb;
   
       		$fromChilds = implode( ", ", $fromChilds );
       		if( !$fromChilds ) return array();
   
       		$getParents = 
       			( is_page() )
       			?	# Pages
       				$wpdb->get_results("
       					SELECT	post_parent AS category_parent
       					FROM	{$wpdb->posts}
       					WHERE	ID IN ({$fromChilds})
       				")
       			: 	# Posts / Categories
       				$wpdb->get_results("
       					SELECT	category_parent
       //					FROM	{$wpdb->categories}
       					FROM	{$wpdb->terms}
       					WHERE	cat_ID IN ({$fromChilds})
       				");
   
       		foreach( $getParents as $getParent )
       			if( $getParent->category_parent != 0 )
       				$allParents[] = $getParent->category_parent;
   
       		return $allParents;
   
       	}
       }
       ```
   
 * and then when I try to use it. I’m really stuck.
 *  [catacaustic](https://wordpress.org/support/users/catacaustic/)
 * (@catacaustic)
 * [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/#post-11659044)
 * Again, it doesn’t have to be in _your_ plugin. It can be in any other plugin 
   or code before your plugin is loaded. A plugin is not an encapsulated littel 
   ball of code. It still has to interact and play nocely with everything else in
   the WordPress system including core, other plugins and themes.
 * Did you remove the if(function_exists()) call as I said? Do that with debugging
   on (WP_DEBUG in your wp_config.php file) and you’ll see where it’s defined, and
   it will be outside of your plugin.

Viewing 15 replies - 1 through 15 (of 19 total)

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The topic ‘Help using a variable in a function parameter’ is closed to new replies.

## Tags

 * [variable](https://wordpress.org/support/topic-tag/variable/)

 * In: [Developing with WordPress](https://wordpress.org/support/forum/wp-advanced/)
 * 19 replies
 * 2 participants
 * Last reply from: [OthelloBloke](https://wordpress.org/support/users/othellobloke/)
 * Last activity: [6 years, 11 months ago](https://wordpress.org/support/topic/help-using-a-variable-in-a-function-parameter/page/2/#post-11659140)
 * Status: resolved

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