@dandi/model and @dandi/model-builder - add @SourceAccessor decorator…

… to allow defining a different or more complex source for a member when constructing a model

supports #13

model-builder/index.ts

@@ -8,6 +8,7 @@ export * from './src/metadata.model.validator';
 export * from './src/metadata.validation.error';
 export * from './src/model.builder';
 export * from './src/model.validation.error';
+export * from './src/nested.key.transformer';
 export * from './src/one.of.conversion.error';
 export * from './src/primitive.type.converter';
 export * from './src/required.property.error';

model-builder/src/decorator.model.builder.spec.ts

@@ -1,5 +1,5 @@
 import { Uuid } from '@dandi/common';
-import { MemberMetadata, OneOf, Property } from '@dandi/model';
+import { MemberMetadata, OneOf, Property, SourceAccessor } from '@dandi/model';
 
 import { expect } from 'chai';
 import { createStubInstance, SinonSpy, SinonStubbedInstance, spy, stub } from 'sinon';
@@ -79,6 +79,72 @@ describe('DecoratorModelBuilder', () => {
       expect(secondCallValue).to.equal('123');
     });
 
+    it('uses the SourceAccessorFn to access the source value if provided', () => {
+      class AccessorFnTest {
+        @SourceAccessor((source: any) => source.foo.bar)
+        @Property(String)
+        public fooBar: string;
+
+        @Property(Boolean)
+        public isAwesome;
+      }
+
+      builder.constructModel(AccessorFnTest, { foo: { bar: 'yup' }, isAwesome: 'true' });
+
+      expect((builder as any).constructMemberInternal).to.have.been.calledTwice;
+
+      const firstCallMeta: MemberMetadata = constructMember.firstCall.args[0];
+      expect(firstCallMeta.type).to.equal(String);
+
+      const firstCallKey = constructMember.firstCall.args[1];
+      expect(firstCallKey).to.equal('fooBar');
+
+      const firstCallValue = constructMember.firstCall.args[2];
+      expect(firstCallValue).to.equal('yup');
+
+      const secondCallMeta: MemberMetadata = constructMember.secondCall.args[0];
+      expect(secondCallMeta.type).to.equal(Boolean);
+
+      const secondCallKey = constructMember.secondCall.args[1];
+      expect(secondCallKey).to.equal('isAwesome');
+
+      const secondCallValue = constructMember.secondCall.args[2];
+      expect(secondCallValue).to.equal('true');
+    });
+
+    it('uses the SourceAccessor path to access the source value if provided', () => {
+      class AccessorPathTest {
+        @SourceAccessor('foo.bar')
+        @Property(String)
+        public fooBar: string;
+
+        @Property(Boolean)
+        public isAwesome;
+      }
+
+      builder.constructModel(AccessorPathTest, { foo: { bar: 'yup' }, isAwesome: 'true' });
+
+      expect((builder as any).constructMemberInternal).to.have.been.calledTwice;
+
+      const firstCallMeta: MemberMetadata = constructMember.firstCall.args[0];
+      expect(firstCallMeta.type).to.equal(String);
+
+      const firstCallKey = constructMember.firstCall.args[1];
+      expect(firstCallKey).to.equal('fooBar');
+
+      const firstCallValue = constructMember.firstCall.args[2];
+      expect(firstCallValue).to.equal('yup');
+
+      const secondCallMeta: MemberMetadata = constructMember.secondCall.args[0];
+      expect(secondCallMeta.type).to.equal(Boolean);
+
+      const secondCallKey = constructMember.secondCall.args[1];
+      expect(secondCallKey).to.equal('isAwesome');
+
+      const secondCallValue = constructMember.secondCall.args[2];
+      expect(secondCallValue).to.equal('true');
+    });
+
     it('assigns the result of constructMemberInternal to each key', () => {
       const value = { prop1: 'foo', prop2: '123' };
       constructMember.restore();

model-builder/src/decorator.model.builder.ts

@@ -40,8 +40,8 @@ export class DecoratorModelBuilder implements ModelBuilder {
 
     typeKeys.forEach((key) => {
       key = this.transformKey(key, options);
-      const objValue = obj[key];
       const memberMetadata = modelMetadata[key];
+      const objValue = this.getSourceValue(obj, key, memberMetadata);
       try {
         result[key] = this.constructMemberInternal(memberMetadata, this.getKey(parentKey, key), objValue, options);
       } catch (err) {
@@ -52,6 +52,23 @@ export class DecoratorModelBuilder implements ModelBuilder {
     return result;
   }
 
+  private getSourceValue(source: any, key: string, memberMetadata: MemberMetadata): any {
+    if (!memberMetadata.sourceAccessor) {
+      return source[key];
+    }
+
+    if (typeof memberMetadata.sourceAccessor === 'function') {
+      return memberMetadata.sourceAccessor(source);
+    }
+
+    return memberMetadata.sourceAccessor.split('.').reduce((source, segment) => {
+      if (!source) {
+        return source;
+      }
+      return source[segment];
+    }, source);
+  }
+
   public constructMember(metadata: MemberMetadata, key: string, value: any, options?: MemberBuilderOptions): any {
     return this.constructMemberInternal(metadata, this.transformKey(key, options || {}), value, options || {});
   }

model-builder/src/nested.key.transformer.ts

@@ -1,5 +1,7 @@
+import { Injectable } from '@dandi/core';
 import { DataTransformer } from './data.transformer';
 
+@Injectable()
 export class NestedKeyTransformer implements DataTransformer {
   public transform(obj: any): any {
     const emptySegments = new Map<any, Set<string>>();

model/src/member.metadata.ts

@@ -1,5 +1,9 @@
 import { Constructor } from '@dandi/common';
 
+export type SourceAccessorFn = <TSource, TMember>(source: TSource) => TMember;
+
+export type MemberSourceAccessor = string | SourceAccessorFn;
+
 export interface MemberMetadata {
   type?: Constructor<any>;
   keyType?: Constructor<any>;
@@ -13,6 +17,7 @@ export interface MemberMetadata {
   format?: string;
   oneOf?: Array<Constructor<any>>;
   json?: boolean;
+  sourceAccessor?: MemberSourceAccessor;
 }
 
 export interface ModelMetadata {

model/src/model.decorator.ts

@@ -3,7 +3,7 @@ import { Constructor, Url } from '@dandi/common';
 import { DateTime } from 'luxon';
 
 import { EMAIL_PATTERN, URL_PATTERN } from './pattern';
-import { getMemberMetadata, MemberMetadata } from './member.metadata';
+import { getMemberMetadata, MemberMetadata, MemberSourceAccessor } from './member.metadata';
 
 const EMAIL_MIN_LENGTH = 6;
 const EMAIL_MAX_LENGTH = 254;
@@ -97,3 +97,9 @@ export function OneOf(...oneOf: Array<Constructor<any>>) {
     oneOf,
   });
 }
+
+export function SourceAccessor(sourceAccessor: MemberSourceAccessor): PropertyDecorator {
+  return modelDecorator.bind(null, {
+    sourceAccessor,
+  });
+}