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Data Model Questions /

Moderators: martimiz, Sean, Ed, biapar, Willr, Ingo, swaiba

Object Relations with many_many

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3 Posts   1204 Views


Community Member, 13 Posts

5 August 2010 at 1:54am

Edited: 19/12/2011 7:14am

Has anyone developed an application with SilverStripe where an object has a many to many relationship with another object, and the related object has a many to many relationship with another object? e.g. Let's say I have a resource, and the resource has stages. A resource can have 1-n stages and a stage can be assigned to 1-n resources. In addition, a stage can have 1-n categories and a category be assigned to 1-n stages for each resource, but the relationship between stages and categories is not the same for every resource. Can SilverStripe handle a data model such as this? What would the workflow look like? In my estimation a user would:
1. Create a resource
2. Assign a stage
3. Assign categories to the stage related to the resource.
4. Repeat steps two and three for each additional stage assigned to the resource.



Community Member, 33 Posts

19 December 2011 at 4:51am

Edited: 19/12/2011 7:14am

I work since four weeks with SS, and my primary concern is not the flashy lights and bells, but the management of a datamodel with several levels : objectA N----M object B N------M object C N------M object D
I have same concerns of yours and I'm afraid that SS is not capable of handing this.
F.Ex the DOM is very nice but only handles up to 2 levels .


Forum Moderator, 1899 Posts

19 December 2011 at 6:48am

Edited: 19/12/2011 7:14am

This is a little confusing the title is "many_many" but the notation in both posts are "1-n" and "n-m"... maybe if you stick to a slightly more long hand "has_many" or "many_many" this would be crystal clear.

Using ModelAdmin I have not come across any relationship depths it is unable to handle in the form...

a has_many b
b has_many c
c has_many d

It opens a greybox popup to edit the relationship and then if you keep drilling down it down replace the greybox popup with the new one. This has a limitation of no back (i.e. once editing d you can only return to a, not c).

If d has_many a this creates a circle and the scaffolding fails - easily fixed by removing it within getCMSFields, but it ends the ability to "drill down" into the relationship.

I normally handle the many_many with multi select rather than the ManyManyComplexTableField, but I assume if I didn't it would allow the editing of the relationship as above.

So to summarise - avoid circular relationships and try to use ModelAdmin.