Question

我正在尝试从rails应用程序中的d3.js给我漂亮的图表。我尝试的其中一张图是forced directed graph。为了创建它，JSON需要采用

格式

{
  "nodes":[
    {"name":"Myriel"},
    {"name":"Napoleon"},
    {"name":"Mlle.Baptistine"},
    {"name":"Mme.Magloire"}
 ],
"links":[
    {"source":1,"target":0,"value":1},
    {"source":2,"target":0,"value":8},
    {"source":3,"target":0,"value":10},
    {"source":3,"target":2,"value":6}
]
}

我目前使用此查询从我的数据库中生成了JSON：

 User.joins("INNER JOIN relationships ON users.id = relationships.user_id").select(" users.name, relationships.source, relationships.target,relationships.value")

在控制器中创建如下

 def index
       render :json =>  User.joins("INNER JOIN relationships ON users.id = relationships.user_id").select(" users.name, relationships.source, relationships.target,relationships.value")
  end
end

，结果如下：

[{"name":"Myriel","source":121,"target":1,"value":1},{"name":"Napoleon","source":119,"target":2,"value":2},    {"name":"Myriel","source":121,"target":1,"value":2},{"name":"Myriel","source":121,"target":3,"value":1},{"name":"Mlle.Baptistine","source":122,"target":2,"value":3}]

有没有一种简单的方法可以将我的JSON映射到我需要的东西？

Answer 1

您可以为User模型编写一个类方法，该方法将根据需要返回json。

def get_json
  json_data = User.joins("INNER JOIN relationships ON users.id = relationships.user_id").select(" users.name, relationships.user_id, relationships.target,relationships.value")

  {
    'nodes' => json_data.collect {|json| json.slice('name')},
    'links' => json_data.collect {|json| json.slice('source', 'target', 'value')}
  }
end

Answer 2

如另一个答案所示，创建一个类方法：

class User
  def self.including_relationships
    User.joins("INNER JOIN relationships ON users.id = relationships.user_id").select("users.name, relationships.user_id, relationships.target,relationships.value").each_with_object(Hash.new{|h, k| h[k] = []}) do |a, obj| 
      obj['nodes'] << a.slice('name')
      obj['links'] << a.slice('source', 'target', 'value')
    end
  end
end

然后在你的控制器中：

def index
  render :json =>  User.including_relationships
end

我将方法命名为including_relationships，因为它并没有真正创建JSON而是将数据转换为Hash对象，您可以根据需要对其进行命名。

如何在rails

2 个答案: