mirror of https://gitee.com/bigwinds/arangodb
36 lines
1.5 KiB
Plaintext
36 lines
1.5 KiB
Plaintext
!CHAPTER Starting from Scratch
|
|
|
|
ArangoDB provides the *edges*, *inEdges*, and *outEdges* methods for edge collections.
|
|
These methods can be used to quickly determine if a vertex is connected to other vertices,
|
|
and which.
|
|
This functionality can be exploited to write very simple graph queries in JavaScript.
|
|
|
|
For example, to determine which edges are linked to the *world* vertex, we can use *inEdges*:
|
|
|
|
db.e.inEdges('v/world').forEach(function(edge) {
|
|
require("internal").print(edge._from, "->", edge.type, "->", edge._to);
|
|
});
|
|
|
|
*inEdges* will give us all ingoing edges for the specified vertex *v/world*. The result
|
|
is a JavaScript list, that we can iterate over and print the results:
|
|
|
|
v/continent-africa -> is-in -> v/world
|
|
v/continent-south-america -> is-in -> v/world
|
|
v/continent-asia -> is-in -> v/world
|
|
v/continent-australia -> is-in -> v/world
|
|
v/continent-europe -> is-in -> v/world
|
|
v/continent-north-america -> is-in -> v/world
|
|
|
|
Note that *edges*, *inEdges*, and *outEdges* return a list of edges. If we want to retrieve
|
|
the linked vertices, we can use each edges' *_from* and *_to* attributes as follows:
|
|
|
|
db.e.inEdges('v/world').forEach(function(edge) {
|
|
require("internal").print(db._document(edge._from).name, "->", edge.type, "->", db._document(edge._to).name);
|
|
});
|
|
|
|
We are using the *document* method from the *db* object to retrieve the connected vertices now.
|
|
|
|
While this may be sufficient for one-level graph operations, writing a traversal by hand
|
|
may become too complex for multi-level traversals.
|
|
|