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[skip/helpers] Add join_one()/join_many() helpers.
Example usage for `join_one()`: ``` type User = { name: string; email: string; }; type Post = { title: string; body: string; author_id: number; }; type PostWithAuthor = { title: string; body: string; author: User; }; ... // The following turns `Post`s and `User`s into `PostWithAuthor`s. join_one(posts, users, { on: "author_id", name: "author", }) ``` Example usage for `join_many()`: ``` type Upvote = { post_id: number; user_id: number; }; type Post = { title: string; body: string; }; type PostWithUpvotes = { title: string; body: string; upvotes: { user_id: number; }[]; }; ... // The following turns `Post`s and `Upvote`s into `PostWithUpvote`s. join_many(posts, upvotes, { on: "post_id", name: "upvotes", }) ```
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‎skipruntime-ts/helpers/src/index.ts‎

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@@ -14,3 +14,4 @@ export {
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export { SkipExternalService } from "./remote.js";
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export { SkipServiceBroker, fetchJSON, type Entrypoint } from "./rest.js";
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export { Count, Max, Min, Sum } from "./utils.js";
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export { join_one, join_many } from "./join.js";

‎skipruntime-ts/helpers/src/join.ts‎

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import type {
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EagerCollection,
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Json,
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JsonObject,
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Values,
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Mapper,
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DepSafe,
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} from "@skipruntime/core";
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class JoinOneMapper<
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IdProperty extends keyof VLeft,
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JoinedProperty extends string,
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K extends Json,
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VLeft extends JsonObject & { [P in IdProperty]: Json },
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VRight extends Json,
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> implements
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Mapper<
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K,
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VLeft,
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K,
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Omit<VLeft, IdProperty> & Record<JoinedProperty, VRight>
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>
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{
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constructor(
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private readonly right: EagerCollection<VLeft[IdProperty], VRight>,
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private readonly on: IdProperty,
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private readonly name: JoinedProperty,
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) {}
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mapEntry(
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key: K,
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values: Values<VLeft>,
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): Iterable<[K, Omit<VLeft, IdProperty> & Record<JoinedProperty, VRight>]> {
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return values.toArray().map((v: VLeft) => {
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const { [this.on]: key_right, ...value_left } = v;
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const value_right = {
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[this.name]: this.right.getUnique(key_right),
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} as Record<JoinedProperty, VRight>;
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const value_out = { ...value_left, ...value_right } as const;
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return [key, value_out];
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});
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}
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}
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export function join_one<
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IdProperty extends keyof V1,
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JoinedProperty extends string,
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K extends Json,
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V1 extends JsonObject & { [P in IdProperty]: Json },
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V2 extends Json,
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>(
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left: EagerCollection<K, V1>,
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right: EagerCollection<V1[IdProperty], V2>,
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options: {
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on: IdProperty;
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name: JoinedProperty;
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},
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): EagerCollection<K, Omit<V1, IdProperty> & Record<JoinedProperty, V2>> {
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return left.map(
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JoinOneMapper<IdProperty, JoinedProperty, K, V1, V2>,
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right,
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options.on,
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options.name,
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);
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}
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class ProjectionMapper<
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ProjectionProperty extends keyof V,
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K extends Json,
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V extends JsonObject & { [P in ProjectionProperty]: Json },
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> implements Mapper<K, V, V[ProjectionProperty], Omit<V, ProjectionProperty>>
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{
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constructor(private readonly proj_property: ProjectionProperty) {}
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mapEntry(
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_key: K,
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values: Values<V>,
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): Iterable<[V[ProjectionProperty], Omit<V, ProjectionProperty>]> {
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return values.toArray().map((v: V) => {
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const { [this.proj_property]: new_key, ...new_value } = v;
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return [new_key, new_value];
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});
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}
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}
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class JoinManyMapper<
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IdProperty extends keyof VRight,
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JoinedProperty extends string,
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K extends Json,
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VLeft extends JsonObject,
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VRight extends JsonObject & { [P in IdProperty]: Json },
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> implements
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Mapper<
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VRight[IdProperty],
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VLeft,
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VRight[IdProperty],
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VLeft & Record<JoinedProperty, Omit<VRight, IdProperty>[]>
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>
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{
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private readonly right: EagerCollection<
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VRight[IdProperty],
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Omit<VRight, IdProperty>
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>;
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constructor(
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right: EagerCollection<K, VRight>,
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on: IdProperty,
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private readonly name: JoinedProperty,
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) {
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this.right = right.map(ProjectionMapper<IdProperty, K, VRight>, on);
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}
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mapEntry(
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key: VRight[IdProperty],
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values: Values<VLeft>,
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): Iterable<
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[
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VRight[IdProperty],
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VLeft & Record<JoinedProperty, Omit<VRight, IdProperty>[]>,
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]
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> {
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return values.toArray().map((value_left: VLeft) => {
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const value_right = { [this.name]: this.right.getArray(key) } as Record<
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JoinedProperty,
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(Omit<VRight, IdProperty> & DepSafe)[]
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>;
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const value_out = { ...value_left, ...value_right };
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return [key, value_out];
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});
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}
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}
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export function join_many<
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IdProperty extends keyof V2,
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JoinedProperty extends string,
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K extends Json,
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V1 extends JsonObject,
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V2 extends JsonObject & { [P in IdProperty]: Json },
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>(
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left: EagerCollection<V2[IdProperty], V1>,
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right: EagerCollection<K, V2>,
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options: {
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on: IdProperty;
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name: JoinedProperty;
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},
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): EagerCollection<
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V2[IdProperty],
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V1 & Record<JoinedProperty, Omit<V2, IdProperty>[]>
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> {
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return left.map(
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JoinManyMapper<IdProperty, JoinedProperty, K, V1, V2>,
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right,
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options.on,
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options.name,
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);
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}

‎skipruntime-ts/tests/src/tests.ts‎

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@@ -21,6 +21,8 @@ import {
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GenericExternalService,
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Sum,
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TimerResource,
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join_one,
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join_many,
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} from "@skipruntime/helpers";
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import { it as mit, type AsyncFunc } from "mocha";
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},
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};
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//// testJoinHelpers
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type Post = { title: string; author_id: number };
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type User = { name: string };
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type Upvote = { user_id: number; post_id: number };
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type JoinServiceInputs = {
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posts: EagerCollection<number, Post>;
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users: EagerCollection<number, User>;
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upvotes: EagerCollection<number, Upvote>;
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};
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type PostWithAuthorAndUpvotes = Omit<Post, "author_id"> & {
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author: User;
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upvotes: Omit<Upvote, "post_id">[];
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};
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type JoinServiceResourceInputs = {
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posts: EagerCollection<number, PostWithAuthorAndUpvotes>;
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};
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class PostsResource implements Resource<JoinServiceResourceInputs> {
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instantiate(
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collections: JoinServiceResourceInputs,
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): EagerCollection<number, PostWithAuthorAndUpvotes> {
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return collections.posts;
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}
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}
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const joinService: SkipService<JoinServiceInputs, JoinServiceResourceInputs> = {
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initialData: {
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posts: [],
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users: [],
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upvotes: [],
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},
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resources: {
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posts: PostsResource,
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},
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createGraph(inputCollections: JoinServiceInputs) {
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const posts_with_author = join_one(
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inputCollections.posts,
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inputCollections.users,
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{
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on: "author_id",
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name: "author",
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},
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);
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const posts = join_many(posts_with_author, inputCollections.upvotes, {
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on: "post_id",
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name: "upvotes",
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});
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return { posts };
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},
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};
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export function initTests(
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category: string,
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initService: (service: SkipService) => Promise<ServiceInstance>,
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new RegExp(/^(?:Error: )?Something goes wrong.$/),
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);
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});
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it("testJoinHelpers", async () => {
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const service = await initService(joinService);
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try {
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service.update("users", [
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[1, [{ name: "Foo" }]],
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[2, [{ name: "Bar" }]],
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]);
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service.update("posts", [
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[1, [{ title: "FooBar", author_id: 1 }]],
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[2, [{ title: "Baz", author_id: 2 }]],
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]);
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service.update("upvotes", [
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[1, [{ post_id: 1, user_id: 1 }]],
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[2, [{ post_id: 1, user_id: 2 }]],
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[3, [{ post_id: 2, user_id: 2 }]],
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]);
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service.instantiateResource("unsafe.fixed.resource.ident", "posts", {});
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expect(service.getAll("posts").payload).toEqual([
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[
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1,
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[
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{
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title: "FooBar",
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author: { name: "Foo" },
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upvotes: [{ user_id: 1 }, { user_id: 2 }],
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},
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],
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],
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[
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2,
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[
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{
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title: "Baz",
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author: { name: "Bar" },
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upvotes: [{ user_id: 2 }],
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},
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],
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],
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]);
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} finally {
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await service.close();
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}
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});
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}

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