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Parameters

Parameters and client fields​

Unlike in GraphQL, there are no global variables (yet!) in Isograph. Instead, all parameters used in a client field must be defined in that client field, and no parameters can be unused. Example:

export const PetDetailDeferredRouteComponent = iso(`
  field Query.PetDetailRoute($id: ID!) @component {
    pet(id: $id) {
      PetDetail
    }
  }
`)(function PetDetailRouteComponent({ data }) {
  // ...
});

Accessing parameters at runtime​

The parameters with which a client field was read can be accessed as part of that first parameter. For example:

export const PetDetailDeferredRouteComponent = iso(`
  field Query.PetDetailRoute($id: ID!) @component {
    pet(id: $id) {
      PetDetail
    }
  }
`)(function PetDetailRouteComponent({ data, parameters }) {
  console.log('hello from pet ' + parameters.id + '!');
  // ...
});

Loadable fields are variables​

Parameters can be omitted in isograph literals from loadably selected client fields. Those missing variables become parameters that you must pass when making the network request (i.e. loading the field):

export const BlogItem = iso(`
  field BlogItem.BlogItemDisplay @component {
    # Assume that BlogItemMoreDetail accepts an includeImages: Boolean! parameter
    # that we are skipping here, which is allowed because the field is selected
    # loadably:
    BlogItemMoreDetail @loadable(lazyLoadArtifact: true)
  }
`)(({ data: blogItem }) => {
  const { fragmentReference, loadFragmentReference } =
    useImperativeLoadableField(blogItem.BlogItemMoreDetail);

  const loadBlogItem = () =>
    loadFragmentReference({
      // now, includeImages must be passed here:
      includeImages: true,
    });
});

Typechecking​

There is no typechecking of variables, except to inasmuch as nullable variables are allowed to be missing. This feature is coming soon!