***

title: "Implementing HasCustomFields"
metaTitle: "Adding Custom Fields Support to Custom Vendure Entities"
metaDescription: "Make your own plugin entities support Vendure custom fields by implementing the HasCustomFields interface, with full GraphQL API and UI integration."
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------

From Vendure v2.2, it is possible to add support for [custom fields](/current/core/developer-guide/custom-fields/) to your custom entities. This is useful when you are defining a custom entity as part of a plugin which is intended to be used by other developers. For example, a plugin which defines a new entity for storing product reviews might want to allow the developer to add custom fields to the review entity.

## Defining entities that support custom fields

First you need to update your entity class to implement the `HasCustomFields` interface, and provide an empty class
which will be used to store the custom field values:

```ts title="src/plugins/reviews/entities/product-review.entity.ts"
import {
    DeepPartial,
    HasCustomFields,
    Product,
    VendureEntity,
    ID,
    EntityId,
} from '@vendure/core';
import { Column, Entity, ManyToOne } from 'typeorm';

export class CustomProductReviewFields {} // [!code highlight]

@Entity()
export class ProductReview extends VendureEntity implements HasCustomFields { // [!code highlight]
    constructor(input?: DeepPartial<ProductReview>) {
        super(input);
    }

    @Column(() => CustomProductReviewFields) // [!code highlight]
    customFields: CustomProductReviewFields; // [!code highlight]
    
    @ManyToOne(() => Product)
    product: Product;

    @EntityId()
    productId: ID;

    @Column()
    text: string;

    @Column()
    rating: number;
}
```

### Type generation

Given the above entity your [API extension](/current/core/developer-guide/extend-graphql-api/) might look like this:

```graphql
type ProductReview implements Node {
  id: ID!
  createdAt: DateTime!
  updatedAt: DateTime!

  product: Product!
  productId: ID!
  text: String!
  rating: Int!
}

input CreateProductReviewInput {
  productId: ID!
  text: String!
  rating: Int!
}

input UpdateProductReviewInput {
  id: ID!
  productId: ID
  text: String
  rating: Int
}
```

Notice the lack of manually defining `customFields` on the types, this is because Vendure extends the types automatically once your entity implements `HasCustomFields`.

:::important Naming convention
In order for Vendure to find the correct input types to extend to, they must conform to the naming convention of:

* `Create<EntityName>Input`
* `Update<EntityName>Input`

And if your entity is [supporting translations](/current/core/developer-guide/translatable):

* `<EntityName>Translation`
* `<EntityName>TranslationInput`
* `Create<EntityName>TranslationInput`
* `Update<EntityName>TranslationInput`
  :::

Following this caveat, codegen will now produce correct types including `customFields`-fields like so:

```ts
export type ProductReview = Node & {
  customFields?: Maybe<Scalars['JSON']['output']>; // [!code highlight]
  // Note: Other fields omitted for brevity
}

export type CreateProductReviewInput = {
  customFields?: InputMaybe<Scalars['JSON']['input']>; // [!code highlight]
  // Note: Other fields omitted for brevity
}

export type UpdateProductReviewInput = {
  customFields?: InputMaybe<Scalars['JSON']['input']>; // [!code highlight]
  // Note: Other fields omitted for brevity
}
```

## Supporting custom fields in your services

Creating and updating your entity works now by setting the fields like usual, with one important addition being, you mustn't forget to update relations via the `CustomFieldRelationService`. This is needed because a consumer of your plugin may extend the entity with custom fields of type [`relation`](/current/core/developer-guide/custom-fields/#properties-for-relation-fields) which need to get saved separately.

```ts title="src/plugins/reviews/services/review.service.ts"
import { Injectable } from '@nestjs/common';
import { RequestContext, Product, TransactionalConnection, CustomFieldRelationService } from '@vendure/core';

import { ProductReview } from '../entities/product-review.entity';

@Injectable()
export class ReviewService {
    constructor(
      private connection: TransactionalConnection,
      private customFieldRelationService: CustomFieldRelationService, // [!code highlight]
    ) {}

    async create(ctx: RequestContext, input: CreateProductReviewInput) {
        const product = await this.connection.getEntityOrThrow(ctx, Product, input.productId);
        // You'll probably want to do more validation/logic here in a real world scenario
        
        const review = new ProductReview({ ...input, product }); // [!code highlight]
        const savedEntity = await this.connection.getRepository(ctx, ProductReview).save(review); // [!code highlight]
        await this.customFieldRelationService.updateRelations(ctx, ProductReview, input, savedEntity); // [!code highlight]

        return savedEntity;
    }
}
```

## Updating config

Now you'll be able to add custom fields to the `ProductReview` entity via the VendureConfig:

```ts title="src/vendure-config.ts"
import { VendureConfig } from '@vendure/core';

export const config: VendureConfig = {
    // ...
    customFields: {
        ProductReview: [
            { name: 'reviewerName', type: 'string' },
            { name: 'reviewerLocation', type: 'string' },
        ],
    },
};
```

## Migrations

Extending entities will alter the database schema requiring a migration. See the [migrations guide](/current/core/developer-guide/migrations/) for further details.