Define empty list handling options for ListField

Author: CarsonF

src/common/list-field.ts

@@ -1,16 +1,24 @@
 import { applyDecorators } from '@nestjs/common';
+import { ArrayNotEmpty } from 'class-validator';
 import { OptionalField, OptionalFieldOptions } from './optional-field';
 
-export type ListFieldOptions = OptionalFieldOptions;
+export type ListFieldOptions = OptionalFieldOptions & {
+  /**
+   * How should empty lists be handled?
+   */
+  empty?: 'allow' | 'omit' | 'deny';
+};
 
 export const ListField = (typeFn: () => any, options: ListFieldOptions) =>
   applyDecorators(
     OptionalField(() => [typeFn()], {
       optional: false,
       ...options,
       transform: (value) => {
-        const deduped = value ? [...new Set(value)] : value;
-        return options.transform ? options.transform(deduped) : value;
+        let out = value ? [...new Set(value)] : value;
+        out = options.empty === 'omit' && out.length === 0 ? undefined : out;
+        return options.transform ? options.transform(out) : out;
       },
     }),
+    ...(options.empty === 'deny' ? [ArrayNotEmpty()] : []),
   );

src/components/project-change-request/dto/create-project-change-request.dto.ts

@@ -1,7 +1,8 @@
 import { Field, InputType, ObjectType } from '@nestjs/graphql';
+import { NonEmptyArray } from '@seedcompany/common';
 import { Type } from 'class-transformer';
 import { ValidateNested } from 'class-validator';
-import { ID, IdField } from '~/common';
+import { ID, IdField, ListField } from '~/common';
 import { ProjectChangeRequestType } from './project-change-request-type.enum';
 import { ProjectChangeRequest } from './project-change-request.dto';
 
@@ -12,8 +13,8 @@ export abstract class CreateProjectChangeRequest {
   })
   readonly projectId: ID;
 
-  @Field(() => [ProjectChangeRequestType])
-  readonly types: ProjectChangeRequestType[];
+  @ListField(() => ProjectChangeRequestType, { empty: 'deny' })
+  readonly types: NonEmptyArray<ProjectChangeRequestType>;
 
   @Field()
   readonly summary: string;

src/components/project-change-request/dto/update-project-change-request.dto.ts

@@ -1,4 +1,5 @@
 import { Field, InputType, ObjectType } from '@nestjs/graphql';
+import { NonEmptyArray } from '@seedcompany/common';
 import { Type } from 'class-transformer';
 import { ValidateNested } from 'class-validator';
 import { ID, IdField, ListField, NameField, OptionalField } from '~/common';
@@ -11,8 +12,8 @@ export abstract class UpdateProjectChangeRequest {
   @IdField()
   readonly id: ID;
 
-  @ListField(() => ProjectChangeRequestType, { optional: true })
-  readonly types?: readonly ProjectChangeRequestType[];
+  @ListField(() => ProjectChangeRequestType, { optional: true, empty: 'deny' })
+  readonly types?: NonEmptyArray<ProjectChangeRequestType>;
 
   @NameField({ optional: true })
   readonly summary?: string;