Apant Codegen

Install

yarn add @sparklink-pro/apant-codegen

Description

This plugin generate operations code and default type fragments in an opiniated way from a graphql schema and a document containing fragments.
We identify two kinds of Object type: Regular Object types and Operation payload types (ie. The output type of an operation usually used only for the said operation).

A Type is considered as a Operation payload type, if it ends by Payload.

• The type User would be considered as a regular type.
• The type BooksPayload would be considered as an operation payload type.

The default fragment for a given type is _<Type name>.

• The default fragment for a type User would be _User.
• The default fragment for a type BooksPayload would be _BooksPayload.

The alias of the result of an operation is always res.

The generation consists of two steps:

• First, the generator generates default fragments if they don't exist for every regular object types.
• Second, the generator generates operations code for every defined operation in the schema.

Step 1 : Fragments generation

For every type non identified as a regular type (ie. That doesn't end with Payload), the generator will generated a default fragment for that type.
The generated fragment will include all scalar fields of the type but not the fields of the type's subtypes.
If there is no scalar fields in the fragment, the fragment is skipped.
The fragment who doesn't match a real type are removed.

Step 2 : Operations code generation

For every operation defined in the schema, the generator will generate a query or mutation code based on if a fragment for the operation or the payload exists or not.
If a fragment exists with the name of the operation, it will be used. If a fragment exists for the operation payload, it is used as resultset. Otherwise, the resultset is the list of fields of the operation payload type.
If the resultset is a list of fields, the generator will go one level deep to generate the fields selection.

Examples

Given the following schema:

# schema.graphql

type Book {
  id: ID!
  name: string
  rank: Int
}

type BooksPayload {
  books: [Books!]!
  count: Int!
}

query {
  TopBooks: BooksPayload
}

Case 1 : The operation fragment exists

# fragments.graphql

fragment TopBooks on BooksPayload {
  count
  books {
    id
    title
    rank
  }
}
...

The resulting query code will be:

# operations.graphql

query TopBooks {
  res: TopBooks {
    ...TopBooks
  }
}

Case 2 : The payload fragment exists

# fragments.graphql

fragment _BooksPayload on BooksPayload {
  count
  books {
    id
    title
  }
}
...

The resulting query code will be:

# operations.graphql

query TopBooks {
  res: TopBooks {
    ..._BooksPayload
  }
}

Case 3 : Neither the operation fragment, nor the payload fragment exist

# fragments.graphql
...

The resulting query code will be:

# operations.graphql

query TopBooks {
  res: TopBooks {
    count
    books {
      ..._Book
    }
  }
}