[TINKERPOP-2331] Select(<multiple keys>).By(__ValueMap(true)) throws "Unable to cast" exception

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Cannot Reproduce
• Affects Version/s: 3.4.4
• Component/s: dotnet
• Assignee: Unassigned
• Reporter: Tom Brown
• Created: 24/Jan/20 06:27
• Updated: 05/May/20 17:21
• Resolved: 05/May/20 17:21

Description

It looks like dotnet version does not support selecting multiple vertices by aliases and following syntax always throws an exception

Select("key1", "key2").By(__.ValueMap(true))

System.InvalidCastException: 'Unable to cast object of type 'System.Collections.Generic.Dictionary`2[System.Object,System.Object]' to type 'Gremlin.Net.Structure.Vertex'.'

 

Steps to reproduce:

1. Create following test graph

graph = TinkerGraph.open();
g = graph.traversal();
g.addV().property("name", "B").
addV().property("name", "A");

 

2. Query from Gremlin console to verify that query syntax is OK

g.V().has("name", "A").as("a").out().has("name", "B").as("b").select("a", "b").by(valueMap(true))

 

3. Query from .net to get an exception

g.V().Has("name", "A").As("a").Out().Has("name", "B").as("b").Select<object>("a", "b").By(__.ValueMap<object, object>(true)).ToList()

 

Hack fix that works

My hacky fix was to create "ByDictionary" method similar to "By", but I could not figure out how to add a proper override to "By"

public GraphTraversal<S, Dictionary<object, object>> ByDictionary(ITraversal traversal)

{ Bytecode.AddStep("by", traversal); return Wrap<S, Dictionary<object, object>>(this); }