EE 2.6.1. Combine relationships and related categories for editorial workflow

Question

On our Single entry pages we recommend other articles. Four slots are available. channel: articles. channel fields: Content Elements field for the text and a native EE Relationship field called "related_articles"

Here´s the editorial workflow: After writing the article an editor can select between 0 and 4 articles manually. The EE-field "related_articles" will be used for that. All relationships are between entries of the same channel.

There are 4 slots to fill. EE will fill the empty slots automatically with articles from the same category.

An example: The editor wrote an article in the category A and manually added one related article. Then EE has to add three more category A articles to the mix.

This is my code for the editor´s picks:

{exp:channel:entries channel="article"}
    {related_articles}
       <p>{related_articles:title}</p>
    {/related_articles}
{/exp:channel:entries}

This is my code for the stuff, that EE adds automatically.

{exp:channel:entries channel='article' 
    related_categories_mode='yes' 
    custom_fields='yes' 
    limit='{4 - count_of_editors_pick}' 
    entry_id='not {the_IDs_from_editors_pick}'
}
  <p>{title}</p>
{/exp:channel:entries}

Both work well solo, but how do I combine them? I tried the math plugin plus the session variables plugin. I stored the {count} for the first loop in {rel_art}, so I know, how many articles the editor added.

{exp:math formula='4 - [1]' params='{exp:session_variables:get name="rel_art"}'}

But it seems, that I run into a parse order issue here. I can´t use this to set the limit parameter within the channel entries tag.

My questions

1. How do I limit EE´s related categories loop so that it fills up the remaining slots?
2. How do I avoid entry dublications? EE should not add any entries choosen by the editor.

Answer 1

Use Stash - Here's how:

{!--  ============================================
STORE A LIST OF RELATED ARTICLES INTO A LIST
================================================== --}

{!-- first the manually chosen ones --}
{exp:stash:set_list name="rels" parse_tags="yes" trim="yes"}
    {exp:channel:entries channel="article"}
        {related_articles}
            {stash:the-title}{related_articles:title}{/stash:the-title}
        {/related_articles}
    {/exp:channel:entries}
{/exp:stash:set_list}

{!-- next append the automatically chosen ones to the same list. No need for more than 4 --}
{exp:channel:entries channel="article" related_categories_mode="yes" custom_fields="yes" limit="4"}
    {exp:stash:append_list name="rels" parse_tags="yes" trim="yes"}
        {stash:the-title}{title}{/stash:the-title}
    {/exp:stash:append_list}
{/exp:channel:entries}

{!--  ============================================
OUTPUT THE DATA
================================================== --}

{exp:stash:parse process="end"}
    <ul>
    {exp:stash:get_list name="rels" unique="yes" limit="4"}
        <li>{the-title}</li>
    {/exp:stash:get_list}
    </ul>
{/exp:stash:parse}

Unique="yes" will prevent any duplicates, and setting the chosen related articles before the automatically chosen ones will ensure that the former takes precedence over the latter.

If you're using a separate embedded template for your display output you won't need the stash:parse tag, but if you're getting and setting in the same template you'll need it here to avoid parse order headaches.