Writing nested object to Apollo client cache

Question

I am trying to write a nested object to apollo cache but it it not working. Simple variables writes are working fine. I am using Apollo-client v2.4

// Schema
const GET_DATA_FROM_CACHE = gql `
  name
  address
  age
`
// Reading data from cache
  render() {
    return (
    <Query query = {GET_DATA_FROM_CACHE} fetchPolicy = {"cache-only"}>
      {({ data }) => (
        <View >
          <Text> Name: {data.name} </Text>
        </View>
      )}
    </Query>
   )
  }

// THIS WORKS as I can see the name in my Text field

client.writeData({
  data: {
    name: 'mr x',
    age: 25
  }
})

// THROWS ERROR: "cannot read property country of undefined"

client.writeData({
  data: {
    name: 'mr x',
    address: {
      country: 'y',
      city: 'z'
    },
    age: 25
  }
})

Please be more specific than "this doesn't work". Are you seeing any errors in the console? What's the expected behavior and what unexpected behavior are you actually seeing when your code runs? — Daniel Rearden
– Daniel Rearden, Commented Mar 7, 2019 at 15:08
It may also be helpful to see how you're querying this client state and what your apollo client config is, since these are both factors that can contribute to something "not working" — Daniel Rearden
– Daniel Rearden, Commented Mar 7, 2019 at 15:10
I have updated the readQuery part. This is very simple write to the cache. I just wanted to add some defaults to the app in cache to check if I can later push my app state from this.state={} to apollo cache — Bijay Timilsina
– Bijay Timilsina, Commented Mar 7, 2019 at 15:36

Andrew Keller · Accepted Answer · 2019-03-07 19:22:37Z

3

I was running into this issue and resolved it by ensuring I included a __typename field with the appropriate value in the nested object. For example:

client.writeData({
  data: {
    name: 'mr x',
    address: {
      id: 1,
      country: 'y',
      city: 'z',
      __typename: "Address"
    },
    age: 25
  }
})

I would also add that it is a good idea to include an 'id' field (unless you've configured the getIdFromObject option). There's more info in Apollo's Cache Normalization section.

For reference, the error I was getting was:

Invariant Violation: Store error: the application attempted to write an object with no provided id but the store already contains an id of {Typename}:{id} for this object.

edited Mar 7, 2019 at 19:22

answered Mar 7, 2019 at 19:10

Andrew Keller

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1 Comment

Bijay Timilsina Over a year ago

Thanks a lot man. I had the '__typename' inside the data for the whole object but didn't have '__typename' for individual nested objects.

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