The GRAPH\_TRAVERSAL function traverses through the graph.

`GRAPH_TRAVERSAL (graphName, startVertexExample, direction, options)`

This function performs traversals on the given graph.

The complexity of this function strongly depends on the usage.

*Parameters*
* *graphName*          : The name of the graph as a string.
* *startVertexExample*        : An example for the desired
vertices (see [example](#short-explanation-of-the-example-parameter)).
* *direction*          : The direction of the edges as a string. Possible values
are *outbound*, *inbound* and *any* (default).
* *options*: Object containing optional options.

*Options*:
 
* *strategy*: determines the visitation strategy. Possible values are 
*depthfirst* and *breadthfirst*. Default is *breadthfirst*.
* *order*: determines the visitation order. Possible values are 
*preorder* and *postorder*.
* *itemOrder*: determines the order in which connections returned by the 
expander will be processed. Possible values are *forward* and *backward*.
* *maxDepth*: if set to a value greater than *0*, this will limit the 
traversal to this maximum depth. 
* *minDepth*: if set to a value greater than *0*, all vertices found on 
a level below the *minDepth* level will not be included in the result.
* *maxIterations*: the maximum number of iterations that the traversal is 
allowed to perform. It is sensible to set this number so unbounded traversals 
will terminate at some point.
* *uniqueness*: an object that defines how repeated visitations of vertices should 
be handled. The *uniqueness* object can have a sub-attribute *vertices*, and a
sub-attribute *edges*. Each sub-attribute can have one of the following values:
  * *"none"*: no uniqueness constraints
  * *"path"*: element is excluded if it is already contained in the current path.
   This setting may be sensible for graphs that contain cycles (e.g. A -> B -> C -> A).
  * *"global"*: element is excluded if it was already found/visited at any 
  point during the traversal.
* *filterVertices*  An optional array of example vertex documents that the traversal will treat specially.
    If no examples are given, the traversal will handle all encountered vertices equally.
    If one or many vertex examples are given, the traversal will exclude any non-matching vertex from the
    result and/or not descend into it. Optionally, filterVertices can contain a string containing the name
    of a user-defined AQL function that should be responsible for filtering.
    If so, the AQL function is expected to have the following signature:

    `function (config, vertex, path)`

    If a custom AQL function is used for filterVertices, it is expected to return one of the following values:

    * [ ]: Include the vertex in the result and descend into its connected edges
    * [ "prune" ]: Will include the vertex in the result but not descend into its connected edges
    * [ "exclude" ]: Will not include the vertex in the result but descend into its connected edges
    * [ "prune", "exclude" ]: Will completely ignore the vertex and its connected edges

* *vertexFilterMethod:* Only useful in conjunction with filterVertices and if no user-defined AQL function is used.
    If specified, it will influence how vertices are handled that don't match the examples in filterVertices:

   * [ "prune" ]: Will include non-matching vertices in the result but not descend into them
   * [ "exclude" ]: Will not include non-matching vertices in the result but descend into them
   * [ "prune", "exclude" ]: Will completely ignore the vertex and its connected edges

@EXAMPLES

A route planner example, start a traversal from Hamburg :

@EXAMPLE_ARANGOSH_OUTPUT{generalGraphTraversal1}
  var examples = require("@arangodb/graph-examples/example-graph.js");
  var g = examples.loadGraph("routeplanner");
| db._query("FOR e IN GRAPH_TRAVERSAL('routeplanner', 'germanCity/Hamburg'," +
| " 'outbound') RETURN e"
).toArray();
~ examples.dropGraph("routeplanner");
@END_EXAMPLE_ARANGOSH_OUTPUT

A route planner example, start a traversal from Hamburg with a max depth of 1
so only the direct neighbors of Hamburg are returned:

@EXAMPLE_ARANGOSH_OUTPUT{generalGraphTraversal2}
  var examples = require("@arangodb/graph-examples/example-graph.js");
  var g = examples.loadGraph("routeplanner");
| db._query("FOR e IN GRAPH_TRAVERSAL('routeplanner', 'germanCity/Hamburg'," +
| " 'outbound', {maxDepth : 1}) RETURN e"
).toArray();
~ examples.dropGraph("routeplanner");
@END_EXAMPLE_ARANGOSH_OUTPUT