Implementation of a ContentAPI namespace used to map generated schema typings into content api responses

strapi-content-api.ts

import {
  Attribute,
  ComponentAttribute,
  DynamicZoneAttribute,
  GetAttribute,
  GetAttributes,
  GetAttributesKey,
  GetAttributeValue,
  GetComponentAttributeValue,
  GetDynamicZoneAttributeValue,
  GetMediaAttributeValue,
  GetRelationAttributeValue,
  MediaAttribute,
  PasswordAttribute,
  PrivateAttribute,
  RelationAttribute,
  utils,
} from '@strapi/strapi';

// Helper used to add an ID attribute to another type
type WithID = { id: number };

// Values resolvers that we need to replace by custom ones & remove from the base GetAttributesValues implementation
type ExcludedValuesResolvers<T extends Attribute> =
  | GetRelationAttributeValue<T>
  | GetComponentAttributeValue<T>
  | GetDynamicZoneAttributeValue<T>
  | GetMediaAttributeValue<T>;

// Custom GetRelationAttributeValue implementation for the content api
type ContentAPIRelationValue<T extends Attribute> = T extends RelationAttribute<
  infer _S,
  infer R,
  infer G
>
  ? R extends `${string}Many`
    ? Omit<ResponseCollection<G>, 'meta'>
    : Response<G>
  : never;

// Custom GetComponentAttributeValue implementation for the content api
type ContentAPIComponentValue<T extends Attribute> = T extends ComponentAttribute<infer U, infer R>
  ? WithID & (R extends true ? GetAttributesValues<U>[] : GetAttributesValues<U>)
  : never;

// Custom GetMediaAttributeValue implementation for the content api
type ContentAPIMediaValue<T extends Attribute> = T extends MediaAttribute<infer R>
  ? R extends true
    ? DataWrapper
    : DataWrapper[]
  : never;

// Custom GetDynamicZoneAttributeValue implementation for the content api
type ContentAPIDynamicZoneValue<T extends Attribute> = T extends DynamicZoneAttribute<infer C>
  ? Array<
      utils.GetArrayValues<C> extends infer P
        ? P extends utils.SchemaUID
          ? GetAttributesValues<P> & { __component: P } & WithID
          : never
        : never
    >
  : never;

// Aggregation of all the custom content api's custom value resolvers
type ContentAPIValueResolvers<T extends Attribute> =
  | ContentAPIRelationValue<T>
  | ContentAPIComponentValue<T>
  | ContentAPIDynamicZoneValue<T>
  | ContentAPIMediaValue<T>;

// Custom GetAttributeValue implementation based on specific content api rules
// If the given attribute isn't handled by the custom resolvers, then it'll fallback
// to the base implementation and its resolvers
type GetValue<T extends utils.SchemaUID, U extends GetAttributesKey<T>> = GetAttribute<
  T,
  U
> extends infer P
  ? P extends Attribute
    ? ContentAPIValueResolvers<P> | Exclude<GetAttributeValue<P>, ExcludedValuesResolvers<P>>
    : never
  : never;

// Get the list of allowed attributes' names for the content api
// Removes privates and password fields for now
// note: creatorsFields are already handled since their private value is dynamic (set at content-type loading & dumped into the schemas typings)
type GetAllowedAttributesKey<T extends utils.SchemaUID> = GetAttributes<T> extends infer A
  ? keyof Omit<A, utils.KeysBy<A, PrivateAttribute | PasswordAttribute>>
  : never;

// Custom GetAttributesValues implementation which includes specific
// content API logic (sanitation, custom value resolvers, etc...)
type GetAttributesValues<T extends utils.SchemaUID> = {
  [key in GetAllowedAttributesKey<T>]?: GetValue<T, key>;
};

// Wrapper which contains the id/attributes couple, used to type the responses' data property
interface DataWrapper<T extends utils.SchemaUID | null = null> extends WithID {
  attributes: T extends utils.SchemaUID ? GetAttributesValues<T> : any;
}

// Represent a response structure for a single entity
export interface Response<T extends utils.SchemaUID> {
  data: DataWrapper<T> | null;
}

// Represent a response structure for an entity collection
export interface ResponseCollection<T extends utils.SchemaUID> {
  data: DataWrapper<T>[] | null;
  meta: CollectionMetadata;
}

export interface CollectionMetadata {
  pagination: {
    page: number;
    pageSize: number;
    pageCount: number;
    total: number;
  };
}