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A way to call plugin assets only when needed

gjr Member
in Plugins
Just a discussion starter, or maybe there is already a way to do this that I am missing. Developing a plugin, and would like to add script/css links in the header when needed, using the applicable filter. However, I do not need to load these on most pages, but it could be variable, so I cannot simply check the $zp_current_page in the plugin file. Any suggestions on another way?

Even core extensions load all their scripts/css on pages when not necessary. For example, on my index page, I am loading rating and comment pagination js and css when it will never be needed.

Comments

  • jphilbert Member
    The only way I see that i can be done is manually.. add something the template file that is loading to disable them ..but you are right .. why load something if on that page its not gonna be used.
  • acrylian Administrator, Developer
    If it is just the theme page like album.php, image.php, pages.php etc. you wish to address you can use `$_zp_gallery_page`.

    Btw, most (we probably missed some) globals are listed here:
    http://www.zenphoto.org/news/zenphotos-global-variables

    There are also a lot of other functions to test like `is_Pages()`, `is_Newspage()`. Also there are way to test the context like `in_context()`.

    If you need to address specific albums or pages itself and not just the theme page you have to add checks there as well.

    Regarding plugins you think loading stuff where they should not please open tickets. Might very well be that we did miss some.
  • gjr Member
    Thanks acrylian, yes I was aware of the methods you mention. I am talking about specifically accessing the 'head_filter' say when a plugin function is called, since the function could be called on various pages or contexts. But it looks like by the time that happens the filter has already been processed.

    I will look at some of the core extensions for ideas. And also look to see how comment pagination/rating scripts are loaded and submit tickets. Thanks -
  • acrylian Administrator, Developer
    PHP is always already processed if the page is displayed (you know that of course...:-)). So you cannot dynamically add anything to the filter after the page has been displayed based upon any action. Unless you use JS/jQuery magic in the functions attached of course.

    If your function attached to the filter does not return anything if it is not on the right page or in the right context nothing happens.

    Maybe I don't understand what you are after?
  • gjr Member
    OK, here is my scenario:

    1. I have a user plugin.
    2. In the plugin class I have a function that can be called in template files or codeblocks.
    3. When the function is called, in order for it to work, I need to place scripts and css calls in the <head> (ideally).

    Currently I have this in the "plugin".php, outside of the main function:
    `zp_register_filter('theme_head','printJSwhatever...');`

    which calls a function to print the necessary js/css calls in the <head>. But it makes this call ALWAYS, on every page when the plugin is activated. I am looking for the possibility to only print this when the main plugin function is called either by a template page or codeblock entry. Not an expert in php or zp plugin architecture, probably something simple.... :)
  • acrylian Administrator, Developer
    You could try to put the filter call within the function called. I have never tried that and I am not sure it works regarding the load order of filters and plugins. Might be the filter execution is already done. Sbillard will surely be able to tell more about that.
  • gjr Member
    Yes already tried that, seems to not work (filter is already processed at that time?)
  • acrylian Administrator, Developer
    Yes, I think the filters are loaded first (as are the template functions etc) in the loading order since function calls later might need them already.

    If it is just a bit JS you could print that with the function itself as it does not matter where that appears. For CSS that is different of course.
  • sbillard Member
    You can alter the DOM even after the head filters have been invoked, but you would have to do so with javascript that your function emits.

    Generally speaking, your plugin should try to determine what it should be doing when it gets loaded if it can. So, for instance, the colorbox_js filter checks to see if it should register a theme_head filter based on the "page" being rendered.

    If you cannot determine what needs to be in the head until after the head has been created the only means for changing it is with javascript. The "head consolidator" plugin (Zenphoto unsupported repository) is an example of doing that.
  • gjr Member
    OK thanks. I will use the page method or "always on". It is not a critical issue, most people won't even notice I guess...
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