breadcrumb-issues.md

Before explaining the issue why breadcrumb is incomplete accross various Civi forms, let me explain the algorithm how the Civi Breadcrum is built for each link.

Code

https://github.com/civicrm/civicrm-core/blob/master/CRM/Core/Menu.php#L548L585

Algorithm

1. foreach ($paths as path) 
2. $pathElements = explode('/', $path)  // say $path = civicrm/contribute/add
3.  array_pop($pathElements); // here to exclude current page from breadcrumb

4. $currentPath = NULL;
5.  // iterate through each sub path and check if the sub path has title and url
  5.1 while ($newPath = array_shift($pathElements)) {
    5.2 $currentPath = $currentPath ? ($currentPath . '/' . $newPath) : $newPath; 
    // say at second iteration $currentpath is 'civicrm/contribute'

    // add to crumb array, if current-path's title exists in list of paths
    5.3 if (array_key_exists($currentPath, $paths) && isset($menu[$currentPath]['title'])) {
      $crumbs[] = array(
        'title' => $paths[$currentPath]['title'],
        'url' => $paths[$currentPath]['url'],
      );
     }
   }
6.  $paths[$path]['breadcrumb'] = $crumbs;
7. } // end of foreach loop

Bugs

Currently some pages show incomplete breadcrumb because it might be two case which are:

1. Missing breadcrumb : For particular sub-path (as in step 5.2) there is no title present, hence the breadcrumb for that sub path din't got added in the sequence. e.g. 'New Student' - https://dmaster.demo.civicrm.org/civicrm/contact/add?ct=Individual&cst=Student&reset=1 Here the url path is 'civicrm/contact/add' and as per code there should be Home(/) >> CiviCRM(/civicrm) >> Contact Dashboard (civicrm/contact) but currently it shows Home >> CiviCRM as no url -'civicrm/contact' exist in the list of path.

Fix : Register a url 'civicrm/contact' with title 'Contact Dashboard' (i.e. https://dmaster.demo.civicrm.org/civicrm/user?reset=1&id=203&cid=203) Similarly we need to register the missing sub-url in CiviCRM for other urls which has missing breadcrumb(s)

2. Incorrect breadcrumb(s) : It might be the case that sometime wrong breadcrumb is appended. Let me explain with an example - say 'Manage Contribution Pages' whose url is 'civicrm/admin/contribute' and currently Civi translates its breadcrumb as "Home >> CiviCRM >> Administer CiviCRM" where it should be 'Home >> CiviCRM >> CiviContribute Dashboard'. This because there is a sub-path 'civicrm/admin' whose title is 'CiviCRM Administer'.

Fix : Change the url to 'civicrm/contribute/admin' from 'civicrm/admin/contribute'

NOTE: I think its ok to exclude the breadcrumb of current page (as in step 3) because this is how other CMSs render their breadcrumbs.

Core Fix

1. Register missing sub-url in CRM/Core/xml/Menu/Core.xml
2. Correct the url by arranging the menu subparts in correct order as mentioned in Bugs#2/Fix