Hi all,
I’ve just published json_api_query_builder which can transform a JSON-API request with filters, fields, include, sort into an Ecto Query.
Eg:
params = %{
"fields" => %{
"article" => "description",
"comment" => "body",
"user" => "email,username"
},
"filter" => %{
"articles.tag" => "animals"
},
"include" => "articles,articles.comments,articles.comments.user"
}
Blog.Repo.all(Blog.User.Query.build(params))
To map between the JSON-API model and the DB model, the user implements a Query module with callbacks to handle filters, field mapping, preloading relationships, etc…
defmodule Article do
use Ecto.Schema
schema "articles" do
field :body, :string
field :description, :string
field :slug, :string
field :tag_list, {:array, :string}
field :title, :string
belongs_to :author, User, foreign_key: :user_id
has_many :comments, Comment
timestamps()
end
defmodule Query do
use JsonApiQueryBuilder,
schema: Article,
type: "article",
relationships: ["author", "comments"]
@impl JsonApiQueryBuilder
def filter(query, "tag", value), do: from(a in query, where: ^value in a.tag_list)
def filter(query, "comments", params) do
comment_query = from(Comment, select: [:article_id], distinct: true) |> Comment.Query.filter(params)
from a in query, join: c in ^subquery(comment_query), on: a.id == c.article_id
end
def filter(query, "author", params) do
user_query = from(User, select: [:id]) |> User.Query.filter(params)
from a in query, join: u in ^subquery(user_query), on: a.user_id == u.id
end
@impl JsonApiQueryBuilder
def include(query, "comments", comment_params) do
from query, preload: [comments: ^Comment.Query.build(comment_params)]
end
def include(query, "author", author_params) do
from query, select_merge: [:author_id], preload: [author: ^User.Query.build(author_params)]
end
end
end
Links:
