Custom Form Validation

In Refine, we can use the form validation that comes with Ant Design with the rules property of the Form.Item component.

<Form>
  <Form.Item
    label="Title"
    name="title"
    rules={[
      {
        required: true,
      },
      {
        min: 5,
      },
    ]}
  >
    <Input />
  </Form.Item>
  ...
</Form>

In addition to pre-defined rules, we can also prepare custom rules with the validator function.

Example

Now let's prepare a rule that checks if the titles of the posts are unique. We have an endpoint like the below. We will do the uniqueness check here.

https://api.fake-rest.refine.dev/posts-unique-check?title=Example

{
  "isAvailable": true
}

localhost:3000/posts/create

import { useForm, Create, CreateButton } from "@refinedev/antd";
import { Form, Input } from "antd";
import { useApiUrl, useCustom, HttpError } from "@refinedev/core";

interface IPost {
  title: string;
}

interface PostUniqueCheckResponse {
  isAvailable: boolean;
}

interface PostUniqueCheckRequestQuery {
  title: string;
}

const PostCreate: React.FC = () => {
  const { formProps, saveButtonProps } = useForm<IPost>();

  const [title, setTitle] = useState("");

  const apiUrl = useApiUrl();
  const url = `${apiUrl}/posts-unique-check`;
  const { refetch } = useCustom<
    PostUniqueCheckResponse,
    HttpError,
    PostUniqueCheckRequestQuery
  >({
    url,
    method: "get",
    config: {
      query: {
        title,
      },
    },
    queryOptions: {
      enabled: false,
    },
  });

  return (
    <Create saveButtonProps={saveButtonProps}>
      <Form {...formProps} layout="vertical">
        <Form.Item
          label="Title"
          name="title"
          rules={[
            {
              required: true,
            },
            {
              validator: async (_, value) => {
                if (!value) return;
                const { data } = await refetch();
                if (data && data.data.isAvailable) {
                  return Promise.resolve();
                }
                return Promise.reject(new Error("'title' must be unique"));
              },
            },
          ]}
        >
          <Input
            defaultValue="Test"
            onChange={(event) => setTitle(event.target.value)}
          />
        </Form.Item>
      </Form>
    </Create>
  );
};

important

Value must be kept in the state.

<Input onChange={(event) => setTitle(event.target.value)} />

Example​

Example