Relationships – How to know which one is the parent and which one is the child

Question

I am designing a website for a fashion label who have collections every season, and they do multiple 'projects' for each collection. For instance artwork, videos etc. For instance Collection A may have 3 projects attached to it, and Collection B may have 2 projects.

Collections
      - title (text input)
      - url_title (text input)
      - collection-year (text input)
      - season (select dropdown)
      - images (channel images)

Projects
      - title (text input)
      - url_title (text input)
      - project-collection (relationship to collection)
      - project-images (channel images)

Relationships seem like the best way to link a project with a collection. What I'm struggling with though is creating a submenu for the projects that are grouped by collection. For instance...

Collection A
- Project 1A
- Project 2A
- Project 3A

Collection B
- Project 1B
- Project 2B

Any ideas?

Thanks! Michael

Answer 1

If on every project you have to choose the collection it points to, the collections turns being their child entries.

On the menu, grouping by the collections, you gonna have to look for each one parent:

{exp:channel:entries channel="colletions"}
  {title}
  {parents field="project-collection"}
    {parents:title}
  {/parents}
{/exp:channel:entries}

To who is submitting the data, is quite the opposite: they can see every project as a child of the collections. This is why, from a template coding perspective, it can looks like a little confusing.

Think this way: the channel entry which has to be submitted before is always the child and the channel which has the relationship field is always the parent. As the collection have to be created before the projects, they're the child entries.