Possible to check for requested output in resolver

Is it possible to check what is being requested in the resolver for a query? For example, if I have the following schema:

type Query {
    getUser(username: ID){
        email: String
        phone: String
    }
}

Can I create a resolver like this?

...
@query.field("getUser")
def get_user(obj, info, username):
    requested_data = ... # This is what I'm looking for
    response = {}
    if "email" in requested_data:
        response["email"] = get_email(username)
    if "phone" in requested_data:
        response["phone"] = get_phone(username)
    return response

[rafalp]

Closing this one. Feel free to ping me back @tbsf if you feel there’s something else to add.

Potentially we could have a guide on our docs showing how one can introspect which fields are asked in resolver to, say, eagerly fetch data needed in child resolver

[andreasnuesslein]

Adding some information for other people that stumble here:

First of all, this is probably what you’re looking for:

for field_node in info.field_nodes:
    print([f.name.value for f in field_node.selection_set.selections])

# or more to the point:
fields = set()
for fnode in info.field_nodes:
    fields.update({f.name.value for f in fnode.selection_set.selections})

“Why the loop around the inner (more obvious) loop” you might ask…

Taking this example

query {
  getUsername(id:2) {
    email
    phone
  }
  getUsername(id:2) {
    phone
  }
  getSomethingElse(id:5) {
    field_a
    field_b
  }
}

def getUsername(obj: Any, info: GraphQLResolveInfo):
    for fnode in info.field_nodes:
        print([f.name.value for f in fnode.selection_set.selections])

will output:

['email', 'phone']                                                                                                                                                          
['phone']
# but not 
['field_a', 'field_b'] # from getSomethingElse

Which a) is kinda efficient - Ariadne doesn’t call the getUserName twice but rather once with all the required arguments and b) means only the field_nodes that actually map to getUserName are in this list.