setting neo4j uniqueness constraints in py2neo v3

Question

Using v2 py2neo I could put this in __init__.py

graph.cypher.execute("CREATE CONSTRAINT ON (n:User) ASSERT n.username IS UNIQUE")

Why does v3 py2neo

graph.run("CREATE CONSTRAINT ON (n:User) ASSERT n.username IS UNIQUE")

fail with this error?

TypeError: unbound method run() must be called with Graph instance as first argument (got str instance instead)

Wow! You spotted my typo from the error message... I forgot the brackets in graph = Graph() How do you do that? — user1613312, Sep 13 '17 at 16:47
I think you answered my question but I can't give you credit for a comment? — user1613312, Sep 13 '17 at 16:56

score 0 · Accepted Answer · answered Sep 13 '17 at 18:15

You should declare the graph variable this way:

>>> graph = Graph()

instead of (without the brackets):

>>> graph = Graph

Also, alternatively to the graph.run() method you can use the graph.schema.create_uniqueness_constraint() method, like this:

>>> graph.schema.create_uniqueness_constraint("User", "username")

1 Answers1