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How to reference an embedded document in Mongoid? - Printable Version +- 0Day Forums (https://0day.red) +-- Forum: Coding (https://0day.red/Forum-Coding) +--- Forum: Ruby (https://0day.red/Forum-Ruby) +--- Thread: How to reference an embedded document in Mongoid? (/Thread-How-to-reference-an-embedded-document-in-Mongoid) |
How to reference an embedded document in Mongoid? - tyrolese782014 - 07-19-2023 Using Mongoid, let's say I have the following classes: class Map include Mongoid::Document embeds_many :locations end class Location include Mongoid::Document field :x_coord, :type => Integer field :y_coord, :type => Integer embedded_in :map, :inverse_of => :locations end class Player include Mongoid::Document references_one :location end As you can see, I'm trying to model a simple game world environment where a map embeds locations, and a player references a single location as their current spot. Using this approach, I'm getting the following error when I try to reference the "location" attribute of the Player class: Mongoid::Errors::DocumentNotFound: Document not found for class Location with id(s) xxxxxxxxxxxxxxxxxxx. My understanding is that this is because the Location document is embedded making it difficult to reference outside the scope of its embedding document (the Map). This makes sense, but how do I model a direct reference to an embedded document? RE: How to reference an embedded document in Mongoid? - chartresnpmcsb - 07-19-2023 Thinking outside the box, you could make Location its own document and use Mongoid Alize to automatically generate embedded data in your Map document from your Location documents. [To see links please register here] The advantage of this method is that you get efficient queries when conditions are suitable, and slower reference based queries on the original document when there's no other way. RE: How to reference an embedded document in Mongoid? - trimerous728 - 07-19-2023 In my use case, there is no need for the outside object to reference the embedded document. From the mongoid user group, I found the solution: Use referenced_in on the embedded document and NO reference on the outside document. class Page include Mongoid::Document field :title embeds_many :page_objects end class PageObject include Mongoid::Document field :type embedded_in :page, :inverse_of => :page_objects referenced_in :sprite end class Sprite include Mongoid::Document field :path, :default => "/images/something.png" end header_sprite = Sprite.create(:path => "/images/header.png") picture_sprte = Sprite.create(:path => "/images/picture.png") p = Page.create(:title => "Home") p.page_objects.create(:type => "header", :sprite => header_sprite) p.page_objects.first.sprite == header_sprite RE: How to reference an embedded document in Mongoid? - blacklister296469 - 07-19-2023 PLEASE go and VOTE for the "virtual collections" feature on MongoDB's issue tracker: [To see links please register here] It's the 2nd most requested feature, but it still hasn't been scheduled for release. Maybe if enough people vote for it and move it to number one, the MongoDB team will finally implement it. RE: How to reference an embedded document in Mongoid? - ClaySeller48 - 07-19-2023 Because Maps are their own collection, you would need to iterate over every Map collection searching within for the Location your Player is referenced. You can't access embedded documents directly. You have to enter through the collection and work your way down. To avoid iterating all of the Maps you can store both the Location reference AND the Map reference in your Player document. This allows you to chain criteria that selects your Map and then the Location within it. You have to code a method on your Player class to handle this. def location self.map.locations.find(self.location_id) end So, similar to how you answered yourself except you could still store the location_id in your player document instead of using the coord attribs. Another way would be to put Maps, Locations, and Players in their own collections instead of embedding the Location in your Map collection. Then you could use reference relationships without doing anything fancy... however your really just using a hierarchical database likes it's a relational database at this point... RE: How to reference an embedded document in Mongoid? - micrologue91820 - 07-19-2023 My current workaround is to do the following: class Map include Mongoid::Document embeds_many :locations references_many :players, :inverse_of => :map end class Player referenced_in :map field :x_coord field :y_coord def location=(loc) loc.map.users << self self.x_coord = loc.x_coord self.y_coord = loc.y_coord self.save! end def location self.map.locations.where(:x_coord => self.x_coord).and(:y_coord => self.y_coord).first end end This works, but feels like a kluge. |