Use a forked EntityManager for each transaction

Currently, a global EntityManager is used for every operation. This causes an error that can be resolved by setting `allowGlobalContext: true`. But that isn't a great fix, because if you ever make an edit to an entity that fails, you'll never be able to make another change because the global context caches the failed change and never releases it.

package.json

@@ -17,6 +17,7 @@
   "scripts": {
     "clean": "rm -fR lib",
     "build": "tsc",
+    "prepack": "yarn clean && yarn build",
     "dev": "yarn clean && tsc -w",
     "test": "dotenv -e .env -- jest --config ./jest.json --runInBand --forceExit --detectOpenHandles --verbose --silent",
     "ts-node": "ts-node",

src/Resource.ts

@@ -74,7 +74,7 @@ export class Resource extends BaseResource {
   }
 
   public async count(filter: Filter): Promise<number> {
-    return this.orm.em.getRepository(this.model).count(
+    return this.orm.em.fork().getRepository(this.model).count(
       convertFilter(filter),
     );
   }
@@ -84,6 +84,7 @@ export class Resource extends BaseResource {
     const { direction, sortBy } = sort as { direction: 'asc' | 'desc', sortBy: string };
 
     const results = await this.orm.em
+      .fork()
       .getRepository(this.model)
       .find(
         convertFilter(filter), {
@@ -100,6 +101,7 @@ export class Resource extends BaseResource {
 
   public async findOne(id: string | number): Promise<BaseRecord | null> {
     const result = await this.orm.em
+      .fork()
       .getRepository(this.model)
       .findOne(id as any); // mikroorm has incorrect types for `findOne`
 
@@ -115,34 +117,37 @@ export class Resource extends BaseResource {
     if (!pk) return [];
 
     const results = await this.orm.em
+      .fork()
       .getRepository(this.model)
       .find({ [pk]: { $in: ids } });
 
     return results.map((result) => new BaseRecord(wrap(result).toJSON(), this));
   }
 
   public async create(params: Record<string, any>): Promise<Record<string, any>> {
-    const instance = this.orm.em
+    const em = this.orm.em.fork();
+    const instance = em
       .getRepository(this.model)
       .create(flat.unflatten(params));
 
-    await this.validateAndSave(instance);
+    await this.validateAndSave(instance, em);
 
     const returnedParams: Record<string, any> = flat.flatten(wrap(instance).toJSON());
 
     return returnedParams;
   }
 
   public async update(pk: string | number, params: Record<string, any> = {}): Promise<Record<string, any>> {
-    const instance = await this.orm.em
+    const em = this.orm.em.fork();
+    const instance = await em
       .getRepository(this.model)
       .findOne(pk as any); // mikroorm has incorrect types for findOneOrFail
 
     if (!instance) throw new Error('Record to update not found');
 
     const updatedInstance = wrap(instance).assign(flat.unflatten(params));
 
-    await this.validateAndSave(updatedInstance);
+    await this.validateAndSave(updatedInstance, em);
 
     const returnedParams: Record<string, any> = flat.flatten(wrap(updatedInstance).toJSON());
 
@@ -151,6 +156,7 @@ export class Resource extends BaseResource {
 
   public async delete(id: string | number): Promise<void> {
     await this.orm.em
+      .fork()
       .getRepository(this.model)
       .nativeDelete(id as any); // mikroorm has incorrect types for nativeDelete
   }
@@ -161,7 +167,7 @@ export class Resource extends BaseResource {
     return !!model?.name && !!orm?.getMetadata?.().find?.(model.name);
   }
 
-  async validateAndSave(instance: Loaded<AnyEntity>): Promise<void> {
+  async validateAndSave(instance: Loaded<AnyEntity>, em: EntityManager): Promise<void> {
     if (Resource.validate) {
       const errors = await Resource.validate(instance);
       if (errors && errors.length) {
@@ -179,7 +185,7 @@ export class Resource extends BaseResource {
       }
     }
     try {
-      await this.orm.em.persistAndFlush(instance);
+      await em.persistAndFlush(instance);
     } catch (error) {
       // TODO: figure out how to get column name from MikroORM's error metadata
       // It currently seems to return only whole Entity