optional parameters in mutation

[seeden]

I would like to use some parameters in mutations as optional. But I will get next error when I skip second "title" parameter: The inline argument title is expected as a variable but was not provided.

Here is the gql example

  mutation ($id: ID!, $title: String, $language: String) {
    quiz: update(id: $id, title: $title, language: $language) {
      id
    }
  }

As you can see only id is required parameter. But when I will call next mutation I can see described error.

await update({
      variables: {
         id: 1,
         language: 'en',
      },
    });

The truth is that I expected default "undefined" value for title.

[seeden]

I will try to explain why I want to have this feature. I have "Main" component which can use mutation. This component has two routes. Each of them can update a different fields but when one of them wanted to save data it call mutation in the parent component via "onSubmit" callback.

[helfer]

@seeden Thanks for reporting it. I think that counts as a bug, because we want to support the full GraphQL spec.

[helfer]

@seeden Could you submit a PR with a failing test? I think it should be easy to do and would help us a lot!

[stubailo]

Yeah this is a bug where Apollo Client caching expects variables to exist in the variables dictionary: https://github.com/apollostack/apollo-client/blob/56c3cf9033f953bab07bd7d725497f4962120aec/src/data/storeUtils.ts#L62

Should be a one-line fix to replace those with null in the store. BTW this error is duplicated in graphql-anywhere: https://github.com/apollostack/graphql-anywhere/blob/5335986c60786d62734f701385648a7da59ecff1/src/storeUtils.ts#L56

We should factor out storeUtils and put them in graphql-anywhere only.

[seeden]

@stubailo can you use undefined instead of null? Because null value is valid database value and I will use it on the server. When I get undefined I can skip it in my "update" query. I am using temporary fix for my mutation with undefined values.

      variables: {
        title: undefined,
        language: undefined,
        ...attributes,
      },

[stubailo]

Does GraphQL on the server treat undefined differently than null?

[seeden]

Yes. When I send undefined I will get undefined and when I send null I will get null. If the variable is undefined I will ignore this variable on the server but I will use it with null value. I am not sure maybe you can ignore undefined variable on the client and graphql will be ok because I will not get any undefined variables

[stubailo]

Sounds good. If GraphQL servers treat undefined and null differently, we should as well!

[helfer]

@stubailo @seeden currently there's no difference between null and undefined

[seeden]

Thanks @helfer for information. Working with null will be changed as you can see in the merged thread graphql/graphql-spec#83

[helfer]

@seeden which is why I said "currently" 😉 We'll wait until the changes are made in graphql-js, and then update Apollo Client accordingly.

[seeden]

ok than we can use default "null" values as @stubailo mentioned because graphql has support for optional parameters in mutation

[lorensr]

null landed in graphql-js in 0.8.0: https://github.com/graphql/graphql-js/releases/tag/v0.8.0