英文:
Gremlingo: Traverser does not map to value when adding edge between two vertices
问题
我正在使用tinkerpop的gremlin-go库来访问gremlin-server/JanusGraph。在尝试创建两个顶点之间的边时，我遇到了以下错误：
The provided traverser does not map to a value: ...
顶点是通过以下方式添加的：
t.AddV("somenode").Property("some_id", someID).Iterate()
和
t.AddV("someothernode").Property("some_id", someID).Iterate()
其中t是*gremlingo.GraphTraversal。顶点成功添加。
边是通过以下方式添加的：
t.AddE("someedge").
From(
__.V().
HasLabel("somenode").
Has("some_id", someID),
).
To(
__.V().
HasLabel("someothernode").
Has("some_id", someID),
).
Iterate()
这里的t仍然是*gremlingo.GraphTraversal，__是gremlingo.T__的别名。但是边没有创建，并显示上述错误。
在gremlin-console中，通过以下方式添加边g.addE("someedge").from(__.V().hasLabel("somenode").has("some_id","some_id_1")).to(__.V().hasLabel("someothernode").has("some_id","some_id_1"))，其中g是遍历器，可以正常工作。
请注意，我省略了go错误处理部分。
英文:
I am using tinkerpop gremling-go to access gremlin-server/JanusGraph. When trying to create an edge between two vertices, I get the following error
The provided traverser does not map to a value: ...
Vertices are added via
t.AddV("somenode").Property("some_id", someID).Iterate()
and
t.AddV("someothernode").Property("some_id", someID).Iterate()
where t is *gremlingo.GraphTraversal. Vertices are added successfully.
Edge is added via
t.AddE("someedge").
From(
__.V().
HasLabel("somenode").
Has("some_id", someID),
).
To(
__.V().
HasLabel("someothernode").
Has("some_id", someID),
).
Iterate()
where again t is *gremlingo.GraphTraversal and __ is alias for gremlingo.T__. Edge is not created with error output above.
Using gremlin-console adding edge via g.addE("someedge").from(__.V().hasLabel("somenode").has("some_id","some_id_1")).to(__.V().hasLabel("someothernode").has("some_id","some_id_1")) where g is the traversal works just fine.
Note that I left out go error handling.
答案1
得分: 0
你等待异步请求完成了吗？
channel := t.AddV("somenode").Property("some_id", someID).Iterate()
err := <-channel
英文:
Did you wait for async request completion?
channel := t.AddV("somenode").Property("some_id", someID).Iterate()
err := <-channel
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