Imagine I have vertices with properties whose values are lists, e.g:
g.addV('v').property('prop',['a','b','c'])
How do I find cases where prop contains a certain value?
This seemed the obvious thing to try:
g.V().has(P.within('prop'),'a')
But it doesn't work:
gremlin_python.driver.protocol.GremlinServerError: 599: Could not locate method: DefaultGraphTraversal.has([within([a]), test])
If you use the VertexProperty list cardinality (see multi-properties in the docs), you can accomplish it like this:
>>> g.addV('v').property(list_, 'prop', 'a').property(list_, 'prop', 'b').property(list_, 'prop', 'c').next()
v[0]
>>> g.V().has('prop', within('a')).toList()
[v[0]]
Note that list_ is coming from an enum via from gremlin_python.process.traversal import Cardinality.
If it's a real list (not a multi-valued property), then you'll have to unfold the value:
gremlin> g = TinkerGraph.open().traversal()
==>graphtraversalsource[tinkergraph[vertices:0 edges:0], standard]
gremlin> g.addV('v').property('prop',['a','b','c'])
==>v[0]
gremlin> g.V().filter(values('prop').unfold().is('a'))
==>v[0]
// or
gremlin> g.V().has('prop', unfold().is('a'))
==>v[0]
Note that this filter requires a full scan over all vertices as individual list entries cannot be indexed. Hence you should take a look at Jason's answer as multi-properties are usually a much better choice.
