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Jared Kimball
6,896 PointsCreating dynamic, CMS-like fields in rails for different post types
I am building a Rails 4 app that has many different types of posts (50+) and each type of post will have different fields. All posts will share fields and entities in common like :title, :body, :image, :category. Category will be the differentiator between each post type. Only admins can create categories. Say I create a category "sports". On top of the attributes above, it has attributes like :intensity, :equipment, :calories_burned. I have a users model and an admin model. Is there a way to create post types with custom fields/attributes to each type dynamically as an admin user?
3 Answers
Daniel Reedy
25,284 PointsThere are a few different approaches to adding custom fields. You can use ActiveRecord Serialization to store the custom field definitions. You could also create another relationship from Category to define your custom fields, something like this:
Once you've stored your custom fields you will need to add the additional logic to your view to add the correct fields to your form and then you'll need to store that information within the Post model or create an additional model that stores the values for the custom fields.
Overall it is fairly straightforward problem, you ultimately need to decide if it's better to store all that information within the Category and Post models or split it out into related models.
Artem Prytkov
11,932 PointsIf you use PostrgeSQL as database, you might want to store informations about fields for each category (and responces for each post) in Hash. See this thread: stackoverflow.com/questions/8816176/how-can-i-store-a-hash-in-my-database
But it`ll require additional code for building forms, and saving/loading data from it.
Jared Kimball
6,896 PointsArtem, thanks I thought about that last night and it makes total in terms of using a helper method to render form elements. Daniel, thanks a lot man, I'll check out your blog.
Kyle Daugherty
16,441 PointsKyle Daugherty
16,441 PointsHey Daniel Reedy,
What tool did you use to design that schema. Looks sharp.
Thanks!
Jared Kimball
6,896 PointsJared Kimball
6,896 PointsDaniel Reedy, are you missing a has_many :custom_fields association on the category model? This look much more straight forward when you illustrate it this way. How would you approach populating the views? Say some :custom_fields may require text_fields, selections, booleans..?
Artem Prytkov
11,932 PointsArtem Prytkov
11,932 Points@Daniel I think you missed a column in posts where you store actual values for custom attributes
@Jared Custom fields table has type column. If it store actual class, you have to write helper, which build custom field depending on that class,
Daniel Reedy
25,284 PointsDaniel Reedy
25,284 PointsMy answer was not intended to be exhaustive and good catch on the diagram, I did forget to add the addition relationship for Category.
I've done something very similar in the past, to build a dynamic form builder, and I may see if I can abstract the code out of the project.
The short answer is I stored the values for the custom fields in another model, indexed by post so that validations could be included.
Daniel Reedy
25,284 PointsDaniel Reedy
25,284 PointsI wrote a blog post awhile back (which I originally forgot about while answering your question) that demos how I am doing dynamic validations in a project. In the article I discuss how we are dynamically rendering out forms which are defined using a database. Take a look and see if that helps with the implementation. Dynamic Validation in a Rails Model
Kyle Daugherty, I'm using Omnigraffle for the ERD diagram