The type __Schema is not an object in the defined schema, but the GraphQL document is traversing it.

[yayvery]

Uncaught (in promise) Graphcache Error: Invalid Object type: The type `__Schema` is not an object in the defined schema, but the GraphQL document is traversing it.
(Caused At: "IntrospectionQuery" query)

Started getting this error when I passed my schema.json to cacheExchange. Seems to be because __Schema is not defined in my schema.json. Does not seem to have any actual effects and can safely be ignored, but the error should still be fixed.

Possibly related to #269, urql-graphql/urql#889

[andyrichardson]

Hey @danbeneventano thanks for the report!

We added a fix for #269 here - urql-graphql/urql#893

As for why you're seeing a similar issue, I suspect it's related to your schema using the __Schema type outside of the __schema property - any chance you could share your schema?

[disbelief]

I'm having the same issue. Definitely seems to be due to the introspection query that devtoolsExchange runs because when I disable that exchange the error disappears.

Had a look at the fix in urql-graphql/urql#893 but I don't see this logic in the latest version of the schemaPredicates.ts.

Perhaps this is a regression?

[disbelief]

Ah I see the logic changed to use a regex that should match any fieldName beginning with __

For reference, here's the complete error I'm seeing:

Unhandled Rejection (Graphcache Error): Invalid Object type: The type `__Schema` is not an object in the defined schema, but the GraphQL document is traversing it.
(Caused At: "IntrospectionQuery" query)
https://bit.ly/2XbVrpR#3

[disbelief]

Perhaps the problem isn't with the __schema field, but rather with the __typename: "__Schema" in the introspection query response?

[disbelief]

After some more digging I am fairly confident the error is happening because the query used to generate the schema that cacheExchange uses is different from the query devtoolsExchange uses.

Specifically, the cacheExchange query is missing all of the __typename fields that the devtoolsExchange introspection query includes.

I'm generating the schema for cacheExchange using the @graphql-codegen/urql-introspection plugin.

I've opened a ticket for graphql-codegen with full details here: dotansimha/graphql-code-generator#5981

However maybe it's possible for the GraphCache exchange to handle this specific situation better? Here's where the error is coming from: https://github.com/FormidableLabs/urql/blob/4c1a9d9bd3df55207aeff1ffc3e2b3262f27cbc9/exchanges/graphcache/src/ast/schemaPredicates.ts#L70

Here are the two introspection queries and their diff:

########################################
# graphql-codegen introspection query:
########################################
query IntrospectionQuery {
  __schema {
    queryType {
      name
    }
    mutationType {
      name
    }
    subscriptionType {
      name
    }
    types {
      ...FullType
    }
    directives {
      name
      description
      locations
      args {
        ...InputValue
      }
    }
  }
}

fragment FullType on __Type {
  kind
  name
  description
  fields(includeDeprecated: true) {
    name
    description
    args {
      ...InputValue
    }
    type {
      ...TypeRef
    }
    isDeprecated
    deprecationReason
  }
  inputFields {
    ...InputValue
  }
  interfaces {
    ...TypeRef
  }
  enumValues(includeDeprecated: true) {
    name
    description
    isDeprecated
    deprecationReason
  }
  possibleTypes {
    ...TypeRef
  }
}

fragment InputValue on __InputValue {
  name
  description
  type {
    ...TypeRef
  }
  defaultValue
}

fragment TypeRef on __Type {
  kind
  name
  ofType {
    kind
    name
    ofType {
      kind
      name
      ofType {
        kind
        name
        ofType {
          kind
          name
          ofType {
            kind
            name
            ofType {
              kind
              name
              ofType {
                kind
                name
              }
            }
          }
        }
      }
    }
  }
}

########################################
# urql-devtools introspection query:
########################################
query IntrospectionQuery {
  __schema {
    queryType {
      name
      __typename
    }
    mutationType {
      name
      __typename
    }
    subscriptionType {
      name
      __typename
    }
    types {
      ...FullType
      __typename
    }
    directives {
      name
      description
      locations
      args {
        ...InputValue
        __typename
      }
      __typename
    }
    __typename
  }
}

fragment FullType on __Type {
  kind
  name
  description
  fields(includeDeprecated: true) {
    name
    description
    args {
      ...InputValue
      __typename
    }
    type {
      ...TypeRef
      __typename
    }
    isDeprecated
    deprecationReason
    __typename
  }
  inputFields {
    ...InputValue
    __typename
  }
  interfaces {
    ...TypeRef
    __typename
  }
  enumValues(includeDeprecated: true) {
    name
    description
    isDeprecated
    deprecationReason
    __typename
  }
  possibleTypes {
    ...TypeRef
    __typename
  }
}

fragment InputValue on __InputValue {
  name
  description
  type {
    ...TypeRef
    __typename
  }
  defaultValue
}

fragment TypeRef on __Type {
  kind
  name
  ofType {
    kind
    name
    ofType {
      kind
      name
      ofType {
        kind
        name
        ofType {
          kind
          name
          ofType {
            kind
            name
            ofType {
              kind
              name
              ofType {
                kind
                name
                __typename
              }
              __typename
            }
            __typename
          }
          __typename
        }
        __typename
      }
      __typename
    }
    __typename
  }
}

Here is the diff between the two queries:

5d4
<       __typename
9d7
<       __typename
13d10
<       __typename
17d13
<       __typename
25d20
<         __typename
27d21
<       __typename
29d22
<     __typename
42d34
<       __typename
46d37
<       __typename
50d40
<     __typename
54d43
<     __typename
58d46
<     __typename
65d52
<     __typename
69d55
<     __typename
78d63
<     __typename
107d91
<                 __typename
109d92
<               __typename
111d93
<             __typename
113d94
<           __typename
115d95
<         __typename
117d96
<       __typename
119d97
<     __typename