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https://issues.apache.org/jira/browse/TINKERPOP-968?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15197441#comment-15197441
]
pieter martin commented on TINKERPOP-968:
-----------------------------------------
{code}
GraphTraversal gt1 = g.traversal().V(a1).choose(__.out("ab"),
__.out("ab"), __.identity()).path();
while (gt1.hasNext()) {
System.out.println(gt1.next());
}
{code}
returns
{code}
[v[0], v[2]]
{code}
{code}
GraphTraversal gt1 = g.traversal().V(a1).choose(__.out("bb"),
__.out("bb"), __.identity()).path();
while (gt1.hasNext()) {
System.out.println(gt1.next());
}
{code}
returns
{code}
[v[0]]
{code}
Optionally traversing both edges should return both paths.
> Add first class support for an optional traversal
> -------------------------------------------------
>
> Key: TINKERPOP-968
> URL: https://issues.apache.org/jira/browse/TINKERPOP-968
> Project: TinkerPop
> Issue Type: Improvement
> Components: process
> Affects Versions: 3.1.0-incubating
> Reporter: pieter martin
>
> Both SparQL and Cypher use the "Optional" keyword to indicate an optional
> traversal. SQL uses the "left join".
> Gremlin has no first class support for an optional traversal. It can be
> achieved with the choose step but it is verbose, unintuitive and not what the
> choose step is intended for.
> The benefits of optional traversals are many. In particular it makes it
> trivial to load complete subgraphs/trees with one easy to read intuitive
> gremlin statement.
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