It's entirely common to bookmark a site without labeling it "interesting" or "read later" or somehow categorize it. They may have bookmarked a given link or they may have tagged it (or both). Users have two distinct relationships with links. There is one interesting question, though. Many_to_many(:tags, Tag, join_through: LinkTag) Many_to_many(:tagged_links, Link, join_through: LinkTag) call the foreign key for links "link_id" in the join table and call the foreign key for user "user_id", etc), we can just pass the module name of the schema for the join table via the join_through option as below: defmodule Linkly.Link doĪlias Linkly. As long as we use the standard names for foreign keys in our tables (e.g. The third option is for arguments we can pass options to define how the tables are related to each other. The second argument is the module name of the schema. This is completely up to us to chose, but in general it's best to just use the name of the schema. The first argument is an atom that we want to use to access the associated records from in our schema. If a given link has been tagged with a given tag, then there will be a link_tag record with the appropriate foreign keys for links and tags are set.Īll we need to do to set up the many to many association in Ecto is to call the many_to_many/3 function in our schema definition. Similarly, links have a many-to-many relationship with tags and the "link_tags" join table also includes tag_id as foreign keys. If user #n has bookmarked link #m, then there will be a bookmark record with a user_id of n and a link_id of m. Instead, the relationship is tracked through the join table "link_tags", which has both link_ids and user_ids. The neither links nor users have the other as a foreign key in its schema. In our app, links have a many-to-many relationship to users. This time, we'll move on to many_to_many associations and also set up some has_many through associations. , we covered has_many and belongs_to associations and saw some of the conveniences Ecto offers once associations are defined. Would appreciate to get any advices, thanks.This episode we'll add tags to our project and create more advanced associations. Can’t get motivation to preload entity when it could go only with id from API client. = performer, attrs) doĪt this moment I stand on creating user with populating ids manually, because forms from frontend would send everything with populated ids. Performer: defmodule doĪlias MyApp.Production. |> validate_format(:email, unique_constraint(:phone) Import ~w(first_name last_name phone ~w(middle_name)a Migrations: create table(:users) doĪdd :user_id, references(:users, on_delete: :delete_all), null: falseĪdd :country_id, references(:countries), null: falseĪdd :native_language_id, references(:languages), null: falseĪdd :gender_id, references(:genders), null: falseĪdd :status_id, references(:performer_statuses), null: falseĬreate unique_index(:performers, ) Performer required to have user, country, native language and some other references. All of them belongs to User, because Manager can be Performer too. I have Manager, Performer and Client entities. I’m building GraphQL API with Phoenix + Absinthe (still didn’t touch) for my translation company’s CRM. I saw this post on medium about using only id's without assocs, but can’t see this approach confirmed as good in docs or threads. After books (Programming Elixir |> 1.6 and Programming Phoenix |> 1.4) and docs I read through so many posts and threads about using cast_assoc/3 and put_assoc/4 but still have issues with it usage and fully understand. I’m quite new to Elixir and Phonex but I felt in love with it so much.
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