mongoose-reparenting-tree

Implements the materialized path strategy with cascade child re-parenting on delete for storing a hierarchy of documents with mongoose

Usage

Install via NPM

$ npm install mongoose-reparenting-tree

Options

Model.plugin(tree, {
  pathSeparator : '#' // Default path separator
  onDelete :  'REPARENT' // Can be set to 'DELETE' or 'REPARENT'. Default: 'REPARENT'
})

Then you can use the plugin on your schemas

var tree = require('mongoose-tree');

var UserSchema = new Schema({
  name : String
});
UserSchema.plugin(tree);
var User = mongoose.model('User', UserSchema);

var adam = new User({ name : 'Adam' });
var bob = new User({ name : 'Bob' });
var carol = new User({ name : 'Carol' });

// Set the parent relationships
bob.parent = adam;
carol.parent = bob;

adam.save(function() {
  bob.save(function() {
    carol.save();
  });
});

At this point in mongoDB you will have documents similar to

{
  "_id" : ObjectId("50136e40c78c4b9403000001"),
  "name" : "Adam",
  "path" : "50136e40c78c4b9403000001"
}
{
  "_id" : ObjectId("50136e40c78c4b9403000002"),
  "name" : "Bob",
  "parent" : ObjectId("50136e40c78c4b9403000001"),
  "path" : "50136e40c78c4b9403000001#50136e40c78c4b9403000002"
}
{
  "_id" : ObjectId("50136e40c78c4b9403000003"),
  "name" : "Carol",
  "parent" : ObjectId("50136e40c78c4b9403000002"),
  "path" : "50136e40c78c4b9403000001#50136e40c78c4b9403000002#50136e40c78c4b9403000003"
}

The path is used for recursive methods and is kept up to date by the plugin if the parent is changed

API

getChildren

Signature:

getChildren([recursive], cb);

if recursive is supplied and true subchildren are returned

Based on the above hierarchy:

adam.getChildren(function(err, users) {
  // users is an array of with the bob document
});

adam.getChildren(true, function(err, users) {
  // users is an array with both bob and carol documents
});

getAncestors

Signature:

getAncestors(cb);

Based on the above hierarchy:

carol.getAncestors(function(err, users) {
  // users is an array of adam and bob
})

level

Equal to the level of the hierarchy

carol.level; // equals 3

Tests

To run the tests install mocha

npm install mocha -g

and then run

mocha