7

我想从 phoenix 中的 ecto 关联生成 JSON。

这是我的协会：

defmodule Blog.Post do
  use Ecto.Model

  schema "posts" do
    field :title, :string
    field :body, :string
    has_many :comments, Blog.Comment
  end
end

和：

defmodule Blog.Comment do
  use Ecto.Model

  schema "comments" do
    field :content, :string
    belongs_to :post, Blog.Post
  end
end

当我在没有关联的情况下生成 json 时，结果是这样的：

[%Blog.Post{body: "this is the very first post ever!", id: 1,title: "first post"},
 %Blog.Post{body: "Hello nimrod!!!!", id: 12, title: "hi Nimrod"},
 %Blog.Post{body: "editing the body!!!!", id: 6, title: "hello(edit)"}]

json看起来像这样

{"posts": [
    {
        "title": "first post",
        "id": 1,
        "body": "this is the very first post ever!"
    },
    {
        "title": "hi Nimrod",
        "id": 12,
        "body": "Hello nimrod!!!!"
    },
    {
        "title": "hello(edit)",
        "id": 6,
        "body": "editing the body!!!!"
    }
]}

但与协会的结果是这样的

[%Blog.Post{body: "this is the very first post ever!",
 comments: {Ecto.Associations.HasMany.Proxy,
 #Ecto.Associations.HasMany<[name: :comments, target: Blog.Post,
 associated: Blog.Comment, references: :id, foreign_key: :post_id]>}, id: 1,
 title: "first post"},
 %Blog.Post{body: "Hello nimrod!!!!",
 comments: {Ecto.Associations.HasMany.Proxy,
 #Ecto.Associations.HasMany<[name: :comments, target: Blog.Post,
 associated: Blog.Comment, references: :id, foreign_key: :post_id]>}, id: 12,
 title: "hi Nimrod"},
 %Blog.Post{body: "editing the body!!!!",
 comments: {Ecto.Associations.HasMany.Proxy,
 #Ecto.Associations.HasMany<[name: :comments, target: Blog.Post,
 associated: Blog.Comment, references: :id, foreign_key: :post_id]>}, id: 6,
 title: "hello(edit)"}]

使用上述输出，我无法创建正确的 json 输出。我希望 json 看起来像这样

{"posts": [
     {
        "title": "the title",
        "id": 1,
        "body": "the body",
        "comments": [{"content": "a comment"}, {"content": "another comment"}]
     }
     ...
]}

任何帮助，将不胜感激。

4

1 回答 1

6

哎呀，目前没有简单的解决方案。我会尝试类似的东西：

defimpl Poison.Encoder, for: Tuple do
  def encode(proxy, options) do
    Poison.Encoder.List.to_json(proxy.all, options)
  end
end

我们基本上是在为接收上述代理并对所有项目进行编码的元组实现编码器。我们需要为此讨论更好的解决方案。

于 2014-11-08T13:07:03.143 回答