arangodb/Documentation/Books/Drivers/JS/Reference/Graph/EdgeCollection.md

GraphEdgeCollection API

The GraphEdgeCollection API extends the Collection API with the following methods.

graphEdgeCollection.remove

async graphEdgeCollection.remove(documentHandle): Object

Deletes the edge with the given documentHandle from the collection.

Arguments

• documentHandle: string

  The handle of the edge to retrieve. This can be either the _id or the _key of an edge in the collection, or an edge (i.e. an object with an _id or _key property).

Examples

const graph = db.graph('some-graph');
const collection = graph.edgeCollection('edges');

await collection.remove('some-key')
// document 'edges/some-key' no longer exists

// -- or --

await collection.remove('edges/some-key')
// document 'edges/some-key' no longer exists

graphEdgeCollection.edge

async graphEdgeCollection.edge(documentHandle): Object

Retrieves the edge with the given documentHandle from the collection.

Arguments

• documentHandle: string

  The handle of the edge to retrieve. This can be either the _id or the _key of an edge in the collection, or an edge (i.e. an object with an _id or _key property).

Examples

const graph = db.graph('some-graph');
const collection = graph.edgeCollection('edges');

const edge = await collection.edge('some-key');
// the edge exists
assert.equal(edge._key, 'some-key');
assert.equal(edge._id, 'edges/some-key');

// -- or --

const edge = await collection.edge('edges/some-key');
// the edge exists
assert.equal(edge._key, 'some-key');
assert.equal(edge._id, 'edges/some-key');

graphEdgeCollection.save

async graphEdgeCollection.save(data, [fromId, toId]): Object

Creates a new edge between the vertices fromId and toId with the given data.

Arguments

• data: Object

  The data of the new edge. If fromId and toId are not specified, the data needs to contain the properties _from and _to.

• fromId: string (optional)

  The handle of the start vertex of this edge. This can be either the _id of a document in the database, the _key of an edge in the collection, or a document (i.e. an object with an _id or _key property).

• toId: string (optional)

  The handle of the end vertex of this edge. This can be either the _id of a document in the database, the _key of an edge in the collection, or a document (i.e. an object with an _id or _key property).

Examples

const db = new Database();
const graph = db.graph('some-graph');
const collection = graph.edgeCollection('edges');
const edge = await collection.save(
  {some: 'data'},
  'vertices/start-vertex',
  'vertices/end-vertex'
);
assert.equal(edge._id, 'edges/' + edge._key);
assert.equal(edge.some, 'data');
assert.equal(edge._from, 'vertices/start-vertex');
assert.equal(edge._to, 'vertices/end-vertex');

graphEdgeCollection.edges

async graphEdgeCollection.edges(documentHandle): Array<Object>

Retrieves a list of all edges of the document with the given documentHandle.

Arguments

• documentHandle: string

  The handle of the document to retrieve the edges of. This can be either the _id of a document in the database, the _key of an edge in the collection, or a document (i.e. an object with an _id or _key property).

Examples

const db = new Database();
const graph = db.graph('some-graph');
const collection = graph.edgeCollection('edges');
await collection.import([
  ['_key', '_from', '_to'],
  ['x', 'vertices/a', 'vertices/b'],
  ['y', 'vertices/a', 'vertices/c'],
  ['z', 'vertices/d', 'vertices/a']
]);
const edges = await collection.edges('vertices/a');
assert.equal(edges.length, 3);
assert.deepEqual(edges.map(edge => edge._key), ['x', 'y', 'z']);

graphEdgeCollection.inEdges

async graphEdgeCollection.inEdges(documentHandle): Array<Object>

Retrieves a list of all incoming edges of the document with the given documentHandle.

Arguments

• documentHandle: string

  The handle of the document to retrieve the edges of. This can be either the _id of a document in the database, the _key of an edge in the collection, or a document (i.e. an object with an _id or _key property).

Examples

const db = new Database();
const graph = db.graph('some-graph');
const collection = graph.edgeCollection('edges');
await collection.import([
  ['_key', '_from', '_to'],
  ['x', 'vertices/a', 'vertices/b'],
  ['y', 'vertices/a', 'vertices/c'],
  ['z', 'vertices/d', 'vertices/a']
]);
const edges = await collection.inEdges('vertices/a');
assert.equal(edges.length, 1);
assert.equal(edges[0]._key, 'z');

graphEdgeCollection.outEdges

async graphEdgeCollection.outEdges(documentHandle): Array<Object>

Retrieves a list of all outgoing edges of the document with the given documentHandle.

Arguments

• documentHandle: string

  The handle of the document to retrieve the edges of. This can be either the _id of a document in the database, the _key of an edge in the collection, or a document (i.e. an object with an _id or _key property).

Examples

const db = new Database();
const graph = db.graph('some-graph');
const collection = graph.edgeCollection('edges');
await collection.import([
  ['_key', '_from', '_to'],
  ['x', 'vertices/a', 'vertices/b'],
  ['y', 'vertices/a', 'vertices/c'],
  ['z', 'vertices/d', 'vertices/a']
]);
const edges = await collection.outEdges('vertices/a');
assert.equal(edges.length, 2);
assert.deepEqual(edges.map(edge => edge._key), ['x', 'y']);

graphEdgeCollection.traversal

async graphEdgeCollection.traversal(startVertex, opts): Object

Performs a traversal starting from the given startVertex and following edges contained in this edge collection.

Arguments

• startVertex: string

  The handle of the start vertex. This can be either the _id of a document in the database, the _key of an edge in the collection, or a document (i.e. an object with an _id or _key property).

• opts: Object

  See the HTTP API documentation for details on the additional arguments.

  Please note that while opts.filter, opts.visitor, opts.init, opts.expander and opts.sort should be strings evaluating to well-formed JavaScript code, it's not possible to pass in JavaScript functions directly because the code needs to be evaluated on the server and will be transmitted in plain text.

Examples

const db = new Database();
const graph = db.graph('some-graph');
const collection = graph.edgeCollection('edges');
await collection.import([
  ['_key', '_from', '_to'],
  ['x', 'vertices/a', 'vertices/b'],
  ['y', 'vertices/b', 'vertices/c'],
  ['z', 'vertices/c', 'vertices/d']
]);
const result = await collection.traversal('vertices/a', {
  direction: 'outbound',
  visitor: 'result.vertices.push(vertex._key);',
  init: 'result.vertices = [];'
});
assert.deepEqual(result.vertices, ['a', 'b', 'c', 'd']);