CODEWITHSUNDEEP
node.jsmongodbloopbackjs
ggabor
ggabor

Reputation: 1712

Nested (embedded) tree model in loopback with mongodb

I try to figure out how to set a very simple nested "treenode" model in loopback with mongodb. The idea is there will be only one model (for this): treenode which can contain other treenodes. I would like to store them at once via mongodb nested documents:

- TreeNode (document):
  Name: "A",
  Nodes: [          
     { 
       Name: "A-A",
       Nodes: [
          { 
            Name: "A-A-A",
            Nodes: []
          },
          { 
            Name: "A-A-B",
            Nodes: []
          },
          { 
            Name: "A-A-C",
            Nodes: []
          }         
      },       
      { 
       Name: "A-B",
       Nodes: []       
      },  
  ]

Additionally each node at any level has relations to other models.

There will be many top-level root treenodes (documents). Which relation type and how should I use for this?

Upvotes: 3

Views: 3172

Answers (2)

Carlos
Carlos

Reputation: 1277

You should define the nested models separately and then declare them as transient models. Then loopback should store them in its parent model, as explained http://loopback.io/doc/en/lb2/Embedded-models-and-relations.html#transient-versus-persistent-for-the-embedded-model

Define a transient data source

server/datasources.json

{
  ...
  "transient": {
    "name": "transient",
    "connector": "transient"
  }
}

server/model-config.json

{
  ...
  "BaseNode": {
    "dataSource": "db",
    "public": true
  },
  "NestedNode": {
    "dataSource": "transient",
    "public": false
  }
}

And the model definitions should be somthing like this:

common/models/NestedNode.json

{
  "name": "NestedNode",
  "base": "Model",
  "properties": {
      "name": {
          "type": "string"
      }
  },
  "relations": {
    "nodes": {
      "type": "referencesMany",
      "model": "NestedNode",
      "options": {
        "validate": true,
        "forceId": false
      }
    }
}

common/models/BaseNode.json

{
  "name": "BaseNode",
  "base": "PersistedModel",
  "properties": {
     "name": {
        "type": "string"
     }
  },
  ...
  "relations": {
    "nestedNode": {
      "type": "embedsMany",
      "model": "Link",
      "scope": {
        "include": "linked"
      }
    }
  },
  ...
}

You also may experience curcular reference problems.

Upvotes: 0

superkhau
superkhau

Reputation: 2781

Unfortunately, there isn't much documentation on this topic yet. For now, see http://docs.strongloop.com/display/LB/Embedded+models+and+relations

Upvotes: 1

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