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gremlintinkerpopjanusgraphtinkerpop3

Using times() ends in ResponseException "The repeat()-traversal was not defined"

g.V(startVertex)
    .repeat(__.inE().outV())
    .until(__.hasId(targetVertex))
    .path()
    .by(T.label);

Im using Tinkerpop 3.6.1 in Java. I get an timeout exception if between startVertex and targetVertex is no connection. To prevent this, according to https://tinkerpop.apache.org/docs/current/reference/#repeat-step I limited the repeat loop with .times(4) between .until() and .path().

g.V(startVertex)
   .repeat(__.inE().outV())
   .until(__.hasId(targetVertex))
   .times(4)
   .path()
   .by(T.label);

But then it throws following exception:

org.apache.tinkerpop.gremlin.driver.exception.ResponseException: The repeat()-traversal was not defined: RepeatStep(until([HasStep([~id.eq(327684264)])]),null,emit(false))

I also tried .loops().is(4) and placing both between .repeat() and .until() but that didn't change anything.

What else can I do?

Solution

  • Two things to be aware of:

    1. If the graph contains cycles you should use simplePath to avoid running "forever".
    2. You never use until and times together, but you can use loops. I have pasted an example of all this put together below. Note the second has step I added. This is to handle the case where loops is 4, but you did not find the desired target.
    g.V(startVertex)
   .repeat(__.inE().outV().simplePath())
   .until(__.hasId(targetVertex).or().loops().is(4))
   .hasId(targetVertex)
   .path()
   .by(T.label);