Silent breaking of queries after writeFragment

Intended outcome: Sufficient diagnostic information on why React components all of a sudden receive empty data object in case when there is a problem with data in cache (for example, missing fields).

Actual outcome: No errors whatsoever. I had to spend hours digging through apollo-client source code to finally find this one and put a console.log(e) there to figure out the actual reason:

https://github.com/apollographql/apollo-client/blob/master/packages/apollo-client/src/core/QueryManager.ts#L978

How to reproduce the issue: Schema:

type Query {
    a(id: String!): A! 
}

type A {
    id: String!
    b: B!
    a: A!
}

type B {
    id: String!
    c: C!
}

type C {
    id: String! 
}

Query:

query q($id: Int) {
    a(id: $id) {
        id
        b {
            id
        }
        a {
            id
            b {
                id
                c {
                    id
                }
            }
        }
    }
}

Fragment for writeFragment:

fragment update on A {
    id
    b {
        id
    }
}

writeFragment call:

apolloClient.writeFragment({
    fragment: gql`
        fragment update on A {
            __typename
            id
            b {
                __typename
                id
            }
        }
    `,
    id: "a2",
    data: {
        __typename: "A",
        id: "a2",
        b: {
            __typename: "B",
            id: "b3"
        }
    }
});

Initial data in the cache:

{
    a: {
        id: "a1",
        b: {
            id: "b1"
        },
        a: {
            id: "a2",
            b: {
                id: "b2",
                c: {
                    id: "c1"
                }
            }
        }
    }
}

Cache after writeFragment:

{
    a: {
        id: "a1",
        b: {
            id: "b1"
        },
        a: {
            id: "a2",
            b: {
                id: "b3"
            }
        }
    }
};

The query has c field inside the nested b, but the updated cache does not. Which makes the query fail.

Version

• apollo-client@2.0.3

[haizz]

@Poincare Nope, sorry, already spent too much time on this.

[jbaxleyiii]

Thanks for reporting this. There hasn’t been any activity here in quite some time, so we’ll close this issue for now. If this is still a problem (using a modern version of Apollo Client), please let us know. Thanks!