In ant design one can provide a custom validator like the following:

<Form.Item label="First Name">
  {getFieldDecorator("firstName", {
    rules: [
      {
        validator: (rule: any, value: string, cb: (msg?: string) => void) => {
          value.length < 3 ? cb("too short") : cb();
        }
      }
    ]
  })(<Input />)}
</Form.Item>

As you see I'm using typescript and cause its transpiler is really cool it wants me to use rule parameter of validator as well. I can't find any documentation on it and don't know what is good for. So if you can please explain briefly what is it and how it should be used?

In ant design one can provide a custom validator like the following:

<Form.Item label="First Name">
  {getFieldDecorator("firstName", {
    rules: [
      {
        validator: (rule: any, value: string, cb: (msg?: string) => void) => {
          value.length < 3 ? cb("too short") : cb();
        }
      }
    ]
  })(<Input />)}
</Form.Item>

As you see I'm using typescript and cause its transpiler is really cool it wants me to use rule parameter of validator as well. I can't find any documentation on it and don't know what is good for. So if you can please explain briefly what is it and how it should be used?

• javascript
• typescript
• antd
• ant-design-pro

1 Answer 1

As part of Validation Rules validator accepts rules as first argument.

Due to the fact it's a wrapper for async-validator, you can check the Rules specification:

function(rule, value, callback, source, options)

rule: The validation rule in the source descriptor that corresponds to the field name being validated. It is always assigned a field property with the name of the field being validated.

You also can put a breakpoint and see its value for your needs.