makeChangeNullabilityPlugin

Use this plugin to easily change the nullability of fields and arguments in your GraphQL schema.

For more information about nullability in PostGraphile in general (and to help determine if the change that you want to make is wise or misguided), see the FAQ question "Why is it nullable?"

Function signature

The makeChangeNullabilityPlugin function accepts one parameter, a rules object:

function makeChangeNullabilityPlugin(
  rules: ChangeNullabilityRules,
): GraphileConfig.Plugin;

interface ChangeNullabilityRules {
  [typeName: string]: {
    [fieldName: string]:
      | NullabilitySpecString
      | {
          type?: NullabilitySpecString;
          args?: {
            [argName: string]: NullabilitySpecString;
          };
        };
  };
}

Note that the format allows you to indicate the nullability for a field directly, or to pass an object in which you can indicate the field nullability and the nullability of that field's arguments at the same time.

The NullabilitySpecString uses syntax similar to GraphQL's SDL to define the nullability of a field, including control over lists and nested lists:

export type NullabilitySpecString =
  | "" // nullable
  | "!" // non-nullable
  | "[]" // nullable list of nullables
  | "[]!" // non-nullable list of nullables
  | "[!]" // nullable list of non-nullables
  | "[!]!"
  | "[[]]"
  | "[[]]!"
  | "[[]!]"
  | "[[]!]!"
  | "[[!]]"
  | "[[!]]!"
  | "[[!]!]"
  | "[[!]!]!";

Example

To indicate that UsersConnection.nodes should be a non-nullable list of non-nullables you would do:

import { makeChangeNullabilityPlugin } from "postgraphile/utils";

const MyNullabilityPlugin = makeChangeNullabilityPlugin({
  UsersConnection: {
    nodes: "[!]!",
  },
});