Simplify type system

Author: BinaryMuse

src/adapter.ts

@@ -1,5 +1,5 @@
 import { Model } from "./model";
-import { WithId } from "./types";
+import { ModelAttributes, WithId } from "./types";
 
 export interface SaveResult {
   success: boolean;
@@ -14,12 +14,12 @@ export interface SaveResult {
  * @param C - The context type.
  * @param T - The model attributes type.
  */
-export type AdapterConfig<C, T> = {
-  getContext: () => Promise<C>;
-  all: (context: C, matchOrQuery?: Partial<T> | string, bindValues?: any[]) => Promise<WithId<T>[]>;
-  get: (context: C, id: any) => Promise<WithId<T> | null>;
-  getBy: (context: C, matchOrQuery: Partial<T> | string, bindValues?: any[]) => Promise<WithId<T> | null>;
-  insert: (context: C, data: Partial<T>) => Promise<SaveResult>;
-  update: (context: C, model: Model<T>, data: Partial<T>) => Promise<SaveResult>;
-  del: (context: C, model: Model<T>) => Promise<boolean>;
+export type AdapterConfig<T extends ModelAttributes> = {
+  getContext: () => Promise<any>;
+  all: (context: any, matchOrQuery?: Partial<T> | string, bindValues?: any[]) => Promise<WithId<T>[]>;
+  get: (context: any, id: any) => Promise<WithId<T> | null>;
+  getBy: (context: any, matchOrQuery: Partial<T> | string, bindValues?: any[]) => Promise<WithId<T> | null>;
+  insert: (context: any, data: Partial<T>) => Promise<SaveResult>;
+  update: (context: any, model: Model<T>, data: Partial<T>) => Promise<SaveResult>;
+  del: (context: any, model: Model<T>) => Promise<boolean>;
 }

src/model.ts

@@ -1,10 +1,10 @@
-import { PersistenceInfo, WithId } from "./types";
+import { ModelAttributes, ModelType, PersistenceInfo, WithId, WithOptionalId } from "./types";
 
 /**
  * Base class for all models. Set persistence information using the `Persistence` decorator.
  */
-export class Model<T, C = any> {
-  protected static persistence: PersistenceInfo<any, any>;
+export class Model<T extends ModelAttributes> {
+  protected static persistence: PersistenceInfo<Model<any>>;
   protected data: T = {} as T;
   protected changedFields: Set<string> = new Set();
   protected _persisted: boolean;
@@ -15,8 +15,8 @@ export class Model<T, C = any> {
    *
    * @returns The persistence information configured for this model.
    */
-  public static getPersistence<T, C>() {
-    return this.persistence as PersistenceInfo<T, C>;
+  public static getPersistence<T extends ModelAttributes>() {
+    return this.persistence as PersistenceInfo<Model<T>>;
   }
 
   /**
@@ -68,7 +68,7 @@ export class Model<T, C = any> {
    * @param data - The data to initialize the model with.
    * @param persisted - Whether the model is already persisted to the database.
    */
-  constructor(data: T & { id?: any }, persisted: boolean = false) {
+  constructor(data: WithOptionalId<T>, persisted: boolean = false) {
     // TODO: generate ID using context
     this.id = data.id;
     const { id, ...rest } = data;
@@ -89,9 +89,9 @@ export class Model<T, C = any> {
    * @param value - The value to set the field to, if setting a single field. Ignored otherwise.
    * @returns The model instance.
    */
-  public set<K extends keyof T>(key: K, value: T[K]): Model<T, C>;
-  public set(changes: Partial<T>): Model<T, C>;
-  public set<K extends keyof T>(keyOrChanges: K | Partial<T>, value?: T[K]): Model<T, C> {
+  public set<K extends keyof T>(key: K, value: T[K]): Model<T>;
+  public set(changes: Partial<T>): Model<T>;
+  public set<K extends keyof T>(keyOrChanges: K | Partial<T>, value?: T[K]): Model<T> {
     if (typeof keyOrChanges === "string") {
       this.data[keyOrChanges as K] = value as T[K];
       this.changedFields.add(keyOrChanges);
@@ -113,9 +113,9 @@ export class Model<T, C = any> {
    * @param value - The value to set the field to, if setting a single field. Ignored otherwise.
    * @returns The model instance.
    */
-  public put<K extends keyof T>(key: K, value: T[K]): Model<T, C>;
-  public put(changes: Partial<T>): Model<T, C>;
-  public put<K extends keyof T>(keyOrChanges: K | Partial<T>, value?: T[K]): Model<T, C> {
+  public put<K extends keyof T>(key: K, value: T[K]): Model<T>;
+  public put(changes: Partial<T>): Model<T>;
+  public put<K extends keyof T>(keyOrChanges: K | Partial<T>, value?: T[K]): Model<T> {
     if (typeof keyOrChanges === "string") {
       this.data[keyOrChanges as K] = value as T[K];
     } else {
@@ -142,14 +142,14 @@ export class Model<T, C = any> {
    * @param bindValues - Optional array of values to bind to the query if using a SQL string.
    * @returns A promise that resolves to an array of matching models.
    */
-  public static async all<T, M extends Model<T, C>, C = any>(
-    this: new (...args: any[]) => M & Model<T, C>,
+  public static async all<T extends ModelAttributes, M extends Model<T>>(
+    this: new (...args: any[]) => M & Model<T>,
     matchOrQuery?: Partial<T> | string,
     bindValues?: any[]
   ): Promise<M[]> {
-    const { adapter, globalSpec } = (this as unknown as typeof Model<T, C>).getPersistence();
+    const { adapter, globalSpec } = (this as unknown as typeof Model<T>).getPersistence();
     const context = await adapter.getContext();
-    const rows = await adapter.all(context, matchOrQuery as any, bindValues);
+    const rows = await adapter.all(context, matchOrQuery, bindValues);
     let models = rows.map(row => (this as any).fromRow(row)) as M[];
     if (globalSpec?.postLoad) {
       const promises = models.map<Promise<M>>(model => globalSpec?.postLoad?.(context, model as any) as Promise<M>);
@@ -164,11 +164,11 @@ export class Model<T, C = any> {
    * @param id - The ID of the model to load.
    * @returns A promise that resolves to the loaded model, or null if it doesn't exist.
    */
-  public static async get<T, M extends Model<T, C>, C = any>(
-    this: new (...args: any[]) => M & Model<T, C>,
+  public static async get<T extends ModelAttributes, M extends Model<T>>(
+    this: new (...args: any[]) => M & Model<T>,
     id: any
   ): Promise<M | null> {
-    const { adapter, globalSpec } = (this as unknown as typeof Model<T, C>).getPersistence();
+    const { adapter, globalSpec } = (this as unknown as typeof Model<T>).getPersistence();
     const context = await adapter.getContext();
     const row = await adapter.get(context, id);
     if (!row) return null;
@@ -186,12 +186,12 @@ export class Model<T, C = any> {
    * @param bindValues - Optional array of values to bind to the query if using a SQL string.
    * @returns A promise that resolves to the matching model, or null if none found.
    */
-  public static async getBy<T, M extends Model<T, C>, C = any>(
-    this: new (...args: any[]) => M & Model<T, C>,
+  public static async getBy<T extends ModelAttributes, M extends Model<T>>(
+    this: new (...args: any[]) => M & Model<T>,
     matchOrQuery?: Partial<T> | string,
     bindValues?: any[]
   ): Promise<M | null> {
-    const { adapter, globalSpec } = (this as unknown as typeof Model<T, C>).getPersistence();
+    const { adapter, globalSpec } = (this as unknown as typeof Model<T>).getPersistence();
     const context = await adapter.getContext();
     const row = await adapter.getBy(context, matchOrQuery as any, bindValues);
     if (!row) return null;
@@ -208,11 +208,11 @@ export class Model<T, C = any> {
    * @param row - The row to create the model from.
    * @returns The created model.
    */
-  protected static fromRow<T, M extends Model<T, C>, C = any>(
-    this: new (...args: any[]) => M & Model<T, C>,
+  protected static fromRow<T extends ModelAttributes, M extends Model<T>>(
+    this: new (...args: any[]) => Model<T>,
     row: WithId<T>
   ): M {
-    const { fieldSpecs } = (this as unknown as typeof Model<T, C>).getPersistence();
+    const { fieldSpecs } = (this as unknown as typeof Model<T>).getPersistence();
     const data = {} as any;
     for (const key in row) {
       const fieldSpec = fieldSpecs?.[key];
@@ -222,7 +222,7 @@ export class Model<T, C = any> {
       }
     }
 
-    return new this(data, true);
+    return new this(data, true) as M;
   }
 
   /**
@@ -231,7 +231,7 @@ export class Model<T, C = any> {
    * @returns A promise that resolves to the model instance.
    */
   public async save(): Promise<this> {
-    const { adapter, fieldSpecs, globalSpec } = (this.constructor as any).getPersistence() as PersistenceInfo<T, C>;
+    const { adapter, fieldSpecs, globalSpec } = (this.constructor as any).getPersistence() as PersistenceInfo<Model<T>>;
     const fields = this.getChangedFields().filter(field => fieldSpecs?.[field]?.persist !== false);
 
     if (this.persisted && fields.length === 0) return this;

src/persistence.ts

@@ -1,6 +1,6 @@
 import { AdapterConfig } from "./adapter";
 import { Model } from "./model";
-import { FieldSpecs, GlobalSpec, PersistenceInfo } from "./types";
+import { FieldSpecs, GlobalSpec, ModelAttributes, PersistenceInfo } from "./types";
 
 /**
  * Decorator to add persistence information to a model.
@@ -10,12 +10,12 @@ import { FieldSpecs, GlobalSpec, PersistenceInfo } from "./types";
  * @param globalSpec - The `GlobalSpec` to use.
  * @returns A decorator function.
  */
-export function Persistence<T = any, C = any, M extends Model<T, C> = Model<T, C>>(
-  adapter: AdapterConfig<C, T>,
+export function Persistence<T extends ModelAttributes>(
+  adapter: AdapterConfig<T>,
   fieldSpecs?: FieldSpecs<T>,
-  globalSpec?: GlobalSpec<T, C, M>
+  globalSpec?: GlobalSpec<T>
 ) {
   return function (target: any) {
-    target.persistence = { adapter, fieldSpecs, globalSpec } as PersistenceInfo<T, C, M>;
+    target.persistence = { adapter, fieldSpecs, globalSpec } as PersistenceInfo<Model<T>>;
   }
 }

src/types.ts

@@ -1,7 +1,10 @@
 import { AdapterConfig } from "./adapter";
 import { Model } from "./model";
 
+export type ModelAttributes = Record<any, unknown>;
+
 export type WithId<T> = T & { id: any };
+export type WithOptionalId<T> = T & { id?: any };
 
 /**
  * A `ValueEncoder` is a set of functions that encode and decode values from the database to the model.
@@ -25,15 +28,18 @@ export type FieldSpecs<T> = {
   [K in keyof T]?: FieldSpec;
 }
 
-export interface GlobalSpec<T, C, M = Model<T, C>> {
-  preSave?: (context: C, model: M) => Promise<M>;
-  postSave?: (context: C, model: M) => Promise<M>;
-  postLoad?: (context: C, model: M) => Promise<M>;
+export interface GlobalSpec<T extends ModelAttributes> {
+  preSave?: (context: any, model: Model<T>) => Promise<Model<T>>;
+  postSave?: (context: any, model: Model<T>) => Promise<Model<T>>;
+  postLoad?: (context: any, model: Model<T>) => Promise<Model<T>>;
 }
 
-export interface PersistenceInfo<T, C, M extends Model<T, C> = Model<T, C>> {
-  adapter: AdapterConfig<C, T>;
-  fieldSpecs?: FieldSpecs<T>;
-  globalSpec?: GlobalSpec<T, C, M>;
+export type ModelType<M> = M extends Model<infer T> ? T : never;
+
+export interface PersistenceInfo<M extends Model<any>> {
+  adapter: AdapterConfig<ModelType<M>>;
+  fieldSpecs?: FieldSpecs<ModelType<M>>;
+  globalSpec?: GlobalSpec<ModelType<M>>;
 }
 
+

test/advanced-model.test.ts

@@ -3,7 +3,7 @@ import { createSqliteAdapter } from "./sqlite-adapter";
 import { unlink } from 'fs/promises';
 import { existsSync } from 'fs';
 
-interface ComplexAttrs {
+type ComplexAttrs = {
   name: string;
   metadata: Record<string, any>;
   secretKey: string;

test/model.test.ts

@@ -3,7 +3,7 @@ import { createSqliteAdapter } from "./sqlite-adapter";
 import { unlink } from 'fs/promises';
 import { existsSync } from 'fs';
 
-interface PersonAttrs {
+type PersonAttrs = {
   firstName: string;
   lastName: string;
   age: number;

test/sqlite-adapter.ts

@@ -1,4 +1,4 @@
-import { AdapterConfig, Model, WithId } from "../src";
+import { AdapterConfig, Model, ModelAttributes, WithId } from "../src";
 import * as sqlite3 from "sqlite3";
 import { Database, open } from "sqlite";
 
@@ -29,7 +29,7 @@ function generateId() {
   return crypto.randomUUID();
 }
 
-export function createSqliteAdapter<T>(dbName: string, tableName: string): AdapterConfig<Context, T> {
+export function createSqliteAdapter<T extends ModelAttributes>(dbName: string, tableName: string): AdapterConfig<T> {
   let ctx: Context | null = null;
 
   async function getContext() {