Last week I try this query:

  query {
    users {

But I always got

"error": "Field 'space_id' doesn't exist on type 'User'"

According this stackoverflow Question and Answer: GraphQL gem with Rails, can’t seem to find correct type definition?

Field and argument names should be underscored as a convention. They will be converted to camelCase in the underlying GraphQL type and be camelCase in the schema itself.

That’s mean you must pass query in camelCase.