TreeDB

LevelDB backend for hierarchical data.

Store

Storing an object:

var db = require('levelup')('/tmp/treedb');
var tree = require('treedb')(db);
var storeOptions = {
  type: 'person',
  object: {
    name: 'Foo Bar',
    slogan: 'hello world'
  },
  callback: function(err, val) {
    console.log(val);
  }
};
tree.store(storeOptions);

Output:

[ 'person', 'WkvBeQ1yB' ]

Query

Query all person types:

var path = require('path');
var db = require('levelup')('/tmp/treedb');
var tree = require(path.join(__dirname, '..'))(db);
var people = [];
tree.nodes('person') // returns a readable stream
.on('data', function(person) {
  people.push(person);
})
.on('end', function() {
  console.log(people);
});

Output:

[ { key: [ 'person', 'WkvBeQ1yB' ],
    value: { type: 'person', name: 'Foo Bar', slogan: 'hello world' } } ]

Methods

var tree = require('treedb')(db)

Create a new treedb from a leveldb handle db and set it to the tree handle.

tree.store(options)

options: {
  object: Object,
  type: String,
  parentKeys: [parentKey, parentKey, ...],
  callback: Function
}

parentKey = [<type>, <id>]

If parentKeys is null, the obj that is stored will be a top level object.

• obj - object to store
• type - type of object to store as a String
• parentKey - key of the parent object of the obj
• cb - callback function that is called with function(err, obj)

var rstream = tree.nodes(options)

options: {
  type: 'type',
  limit: <Number>,
  indexedField: <'field'>,
  indexedValue: <value>
}

Return a readable object stream rstream with the contents of the nodes of the given type. - type - the type of the node as a string, indexedField - field to sort by and of the indexed value - `indexValue'

var rstream = tree.children(options)

// options: parentKey, type, indexedField, limit, reverse

options: {
  parentKey: ['type', 'id'],
  type: <'type'>,
  indexedField: 'field',
  limit: <Number>,
  reverse: <Boolean>
}

Returns a readable stream of children for parentKey of type type, indexed by indexedField.

var rstream = tree.parents(options)

options: {
  key: ['type', 'id'],
  parentType: <'parentType'>,
  limit: <Number>
}

Returns a readable stream of parents for key of type parentType.

tree.addIndex(options)

options: {
  type: String,
  parentType: <String>,
  field: String,
  callback: Function
}

If parentType is provided, creates a secondary index.

tree.addIndexes(options)

options: {
  indexes: [<index>, ...],
  callback: Function
}

index:  {
  type: String,
  parentType: <String>,
  field: String
}

If parentType is provided, creates a secondary index.

tree.addSecondaryIndex(type, parentType, field, cb)

Deprecated: Instead, use tree.addIndex({..., parentType, ...})

Install

npm install treedb

License

MIT