New to Hooks, trying to wrap my head around the syntax

[creativejay 47]

I really wanted to create this post with some sample code to show that I at least tried to figure it out on my own first, but I'm really struggling with how hooks are even written. I know it's a very simple context for anyone who's already using them (and hopefully it will be for me, soon), but this is my first time.

What I'm trying to achieve in this attempt is to verify/change the name and title fields of a page, of one specific template with one specific field, whenever the page is saved.

Initially, I am using the Family / Name Format for Children to skip the name/title/confirm save page when an author creates a new page in my site using kongondo's ProcessBlog module.

In English, I want to: Detect when a page of template blog_page is saved with the blog_categories field value of Swatch, and replace the title and name string with a concatenated version of the following fields (from the same page): blog_date, createdUser, blog_brand and blog_name.

From what I've read so far, I should build this hook into site/templates/admin.php, and I should use the saveReady() and maybe saveField() hooks. Other than knowing I need to define a custom hook, I really haven't got any idea of where to go from here. 

Here's my mangled first attempt at coding my hook. Hopefully you'll be able to tell how I might be misunderstanding this from the following:

$pages->addHookAfter('saveReady', $this, 'myPageRename);

public function myPageRename($event) {
 }

I'm afraid that's really as far as I've gotten because I have no idea what I'm doing. I try to follow examples but they feel really far removed from context for me.

Thanks for any light that can be shed on this!

[ESRCH 118]

There's a really great and simple example given by ryan here that can help you understand.

In your case, you should be able to do the following (not tested):

$pages->addHook('saveReady', function($event) {
  $sanitizer = wire('sanitizer');
  $pages = $event->object;
  $page = $event->arguments(0); 
  if($page->template == 'blog_page' && $page->blog_categories == 'Swatch') {
    // You can build the string as you wish, here is an example
    $concatenatedName = $page->blog_date;
    $concatenatedName .= '-' . $page->createdUser;
    $concatenatedName .= '-' . $page->blog_brand;
    $concatenatedName .= '-' . $page->blog_name;

    $page->title = $concatenatedName;
    $page->name = $sanitizer->pageName($concatenatedName);
  }
});

[LostKobrakai 5,209]

I find it easier to manage these things in a module like this. Also you need to use a before hook, as saving the page with the new title after saving would trigger an infinite loop. See next posts

<?php

/**
 * ProcessWire 'Hello world' demonstration module
 * 
 * ProcessWire 2.x 
 * Copyright (C) 2014 by Ryan Cramer 
 * Licensed under GNU/GPL v2, see LICENSE.TXT
 * 
 * http://processwire.com
 *
 */

class PutYourNameHere extends WireData implements Module {

	/**
	 * getModuleInfo is a module required by all modules to tell ProcessWire about them
	 *
	 * @return array
	 *
	 */
	public static function getModuleInfo() {

		return array(
			'title' => '', 
			'version' => 1, 
			'summary' => '',
			'singular' => true, 
			'autoload' => true,
			);
	}

	public function init() {
		$this->addHookAfter('Pages::saveReady', $this, 'doStuffOnPage'); 
	}

	public function doStuffOnPage($event) {
		$page = $event->arguments[0]; 

		if($page->template->name === "blog_page" && $page->blog_categories == "Swatch"){
			// Do your thing
		}
	}
	
}

[creativejay 47]

I find it easier to manage these things in a module like this. Also you need to use a before hook, as saving the page with the new title after saving would trigger an infinite loop.

Thank you! So using the string code from @ESRCH in the "//Do your thing" line of your example, I would then install this module in my site and then it will automatically run, or do I need to call it from somewhere else as well?

[LostKobrakai 5,209]

Exactly. You just would do good in renaming the module and placeing it in a file like ModuleClassName.module and mostly it's a good idea to pack it in a folder with this name, too. 

Edit:

Just for your education: The "autoload" config tells processwire to load the module everytime. 

Also you could use this to alert the user in the admin about the modules activity. This will generate a message, e. g. like the one telling you the page has been saved.

$this->message("Changed title according to settings in …");

[creativejay 47]

Brilliant, thank you!

[ESRCH 118]

Putting this in a separate module is indeed cleaner.

You probably already read these pages, but I'm putting the links here just in case, since they really helped me develop my own modules/hooks:

https://processwire.com/api/hooks/

http://wiki.processwire.com/index.php/Module_Creation

Also, the Helloworld Module in /site/modules is a great example module to get going.

[adrian 12,082]

Very good advice from soma (as always).

This is what I usually do:

$this->addHookAfter('Pages::saveReady', $this, 'renameBeforeSave');

public function renameBeforeSave(HookEvent $event) {
        $p = $event->arguments[0];
        $p->name = $new_name;
        $event->return = $p; // maybe this isn't actually needed - haven't tested and can't remember 
        //as soma mentioned - this last line definitely isn't needed!
}

Of course you'll need to add in your logic to limit by template/category and to build up the new name/title.

[Soma 6,629]

Actually saveReady is an after hook and it's especially useful as you know that the page is saved right after that. So no endless recursion and you don't need to save the page. With a before save hook you don't know if an error will occur.

Also no need to set the page back to the argument after you done with manipulating the page. So lots of mis-infos here..

Means the best answer isn't the best really

Edit: removed the 'Solved' flag for now.

[Soma 6,629]

No need for the event->return = $p or anything like that, Adrian

[adrian 12,082]

No need for the event->return = $p or anything like that, Adrian

Yeah, looks like my comment about that crossed with your correction

[creativejay 47]

Thanks @Soma and @adrian! I was having some trouble with it, so I'll rework it!

[LostKobrakai 5,209]

@Soma

I updated my post to reflect this as there could easily be people just copying the whole thing.

[creativejay 47]

@adrian here's the module I made from your code. I'm getting a unexpected T_VARIABLE, expecting T_FUNCTION (line 55) - that would be on "public function renameBeforeSave(HookEvent $event) {"

<?php

/**
 * ProcessWire 'Rename Page' module by forum user creativejay
 *
 * Checks to see if a page uses the template "blog-post" and has a $page->blog_categories value of "Swatch" then redefines the value of $page->title and $page->name
 * 
 * 
 * ProcessWire 2.x 
 * Copyright (C) 2014 by Ryan Cramer 
 * Licensed under GNU/GPL v2, see LICENSE.TXT
 * 
 * http://processwire.com
 *
 */

class RenamePage extends WireData implements Module {

	/**
	 * getModuleInfo is a module required by all modules to tell ProcessWire about them
	 *
	 * @return array
	 *
	 */
	public static function getModuleInfo() {

		return array(

			// The module's title, typically a little more descriptive than the class name
			'title' => 'Rename Page', 

			// version number 
			'version' => 3, 

			// summary is brief description of what this module is
			'summary' => 'Checks to see if a page uses the template blog-post and has a blog_categories value of Swatch then redefines the value of title and name',
			
			// Optional URL to more information about the module
			'href' => 'https://processwire.com/talk/topic/8863-new-to-hooks-trying-to-wrap-my-head-around-the-syntax/',

			// singular=true: indicates that only one instance of the module is allowed.
			// This is usually what you want for modules that attach hooks. 
			'singular' => true, 

			// autoload=true: indicates the module should be started with ProcessWire.
			// This is necessary for any modules that attach runtime hooks, otherwise those
			// hooks won't get attached unless some other code calls the module on it's own.
			// Note that autoload modules are almost always also 'singular' (seen above).
			'autoload' => true, 
		
			// Optional font-awesome icon name, minus the 'fa-' part
			'icon' => 'eraser', 
			);
	}
$this->addHookAfter('Pages::saveReady', $this, 'renameBeforeSave');

public function renameBeforeSave(HookEvent $event) {
        if($page->template->name === "blog_post" && $page->blog_categories == "Swatches"){
        	$concatenatedName = $page->blog_date;
		    $concatenatedName .= '-' . $page->createdUser;
		    $concatenatedName .= '-' . $page->blog_brand;
		    $concatenatedName .= '-' . $page->blog_name;
		    
			$concatenatedTitle = $page->blog_brand;
		    $concatenatedTitle .= ' ' . $page->blog_name;
		
		    $page->title = $concatenatedTitle;
		    $page->name = $sanitizer->pageName($concatenatedName);
		    }
        $event->arguments[0] = $page;
}

Can you spot what I've done wrong?

[LostKobrakai 5,209]

You need to add the hook in the init function as you can see it done in my first post here. The thing you're writing there is a class, these can only hold properties and functions and not raw code, like you did. It's only there to provide functionality, which can be called later. The init function of a module is always called on loading the module.

[adrian 12,082]

Try this:

<?php

/**
 * ProcessWire 'Rename Page' module by forum user creativejay
 *
 * Checks to see if a page uses the template "blog-post" and has a $p->blog_categories value of "Swatch" then redefines the value of $p->title and $p->name
 * 
 * 
 * ProcessWire 2.x 
 * Copyright (C) 2014 by Ryan Cramer 
 * Licensed under GNU/GPL v2, see LICENSE.TXT
 * 
 * http://processwire.com
 *
 */

class RenamePage extends WireData implements Module {

    /**
     * getModuleInfo is a module required by all modules to tell ProcessWire about them
     *
     * @return array
     *
     */
    public static function getModuleInfo() {

        return array(

            // The module's title, typically a little more descriptive than the class name
            'title' => 'Rename Page', 

            // version number 
            'version' => 3, 

            // summary is brief description of what this module is
            'summary' => 'Checks to see if a page uses the template blog-post and has a blog_categories value of Swatch then redefines the value of title and name',
            
            // Optional URL to more information about the module
            'href' => 'https://processwire.com/talk/topic/8863-new-to-hooks-trying-to-wrap-my-head-around-the-syntax/',

            // singular=true: indicates that only one instance of the module is allowed.
            // This is usually what you want for modules that attach hooks. 
            'singular' => true, 

            // autoload=true:indicates the module should be started with ProcessWire.
            // This is necessary for any modules that attach runtime hooks, otherwise those
            // hooks won't get attached unless some other code calls the module on it's own.
            // Note that autoload modules are almost always also 'singular' (seen above).
            'autoload' => true, 
        
            // Optional font-awesome icon name, minus the 'fa-' part
            'icon' => 'eraser', 
            );
    }
    
    public function init() {
        $this->addHookAfter('Pages::saveReady', $this, 'renameBeforeSave');
    }

    public function renameBeforeSave(HookEvent $event) {

        $p = $event->arguments[0];

        if($p->template->name === "blog_post" && $p->blog_categories == "Swatches"){
            $concatenatedName = $p->blog_date;
            $concatenatedName .= '-' . $p->createdUser;
            $concatenatedName .= '-' . $p->blog_brand;
            $concatenatedName .= '-' . $p->blog_name;
            
            $concatenatedTitle = $p->blog_brand;
            $concatenatedTitle .= ' ' . $p->blog_name;
        
            $p->title = $concatenatedTitle;
            $p->name = $sanitizer->pageName($concatenatedName, true);
        }
    }
}

[Martijn Geerts 3,254]

Damn you guys, I don't answer anything anymore.....

[creativejay 47]

Martijn you could proof that last code snippet for us! It's throwing a 500.

[creativejay 47]

Okay, I fixed the mismatched names inside the code (I changed the name to RenameSwatches a few times but the code was still referring to RenamePages). That fixed the 500 error, but nothing happens when I save an existing page.

I suppose I could add a dialog to see if it thinks it's running.

Another thought occurs to me.. the field blog_categories is a Page fieldtype. Would that require an adjustment?

[LostKobrakai 5,209]

Another thought occurs to me.. the field blog_categories is a Page fieldtype. Would that require an adjustment?

// Page field single
if($page->blog_categories->title === "Swatch"){
}

// Page field multiple
if($page->blog_categories->get("title=Swatch")){
}

[Martijn Geerts 3,254]

There's a lot not right in your renameBeforeSave method. Naming is also a little bit weird:

You hook after, but you call the method with before in the name.

$p->blog_categories == "Swatches" // If blog_categories is type of page it will not be a string.

$p->createdUser // is a Page // you can't concatenate it like this.

You can't call $sanitizer like this in module scope. (use $this->sanitizer)

[creativejay 47]

$p->blog_categories->title ?

$p->createdUser->title ?

And I should turn $p->blog_date into a string, I imagine?

[ESRCH 118]

$p->blog_categores->title == 'Swatch';

For the $p->createdUser, you can actually still use $p->createdUser, since the toString method of the page will convert it to its page id.

[kongondo 7,383]

blog_categories is a Multiple Page field. This will not work $p->blog_categories == 'swatch'; This has been pointed out above with example code by LostKobrakai.

Edit - see next post...

Edited January 21, 2015 by kongondo

[creativejay 47]

@kongondo your default blog_categories is, but I changed it to a Single Page field because of the way my (already familiarly strange to you) blog is structured.