Deprecate all fields that reference a named output type in Graphile Engine

DeprecateTypePlugin.ts

import type { Plugin } from "graphile-build";

const makeDeprecateTypePlugin = (typeName: string, deprecationReason: string): Plugin => builder => {
  builder.hook('GraphQLObjectType:fields:field', (field, { graphql }) => {
    if (graphql.getNamedType(field.type).name !== typeName) {
      return field;
    }
    return {
      ...field,
      deprecationReason,
    }
  });
}

// Usage:
//   appendPlugins: [makeDeprecateTypePlugin('TypeToDeprecate', 'Use OtherType instead')]