Formik Patterns

Basic Form Setup

import { useFormik } from 'formik';
import * as yup from 'yup';

const validationSchema = yup.object({
  email: yup.string().email('Invalid email').required('Email is required'),
  password: yup.string().min(8, 'Min 8 characters').required('Password is required'),
});

const LoginForm = () => {
  const formik = useFormik({
    initialValues: {
      email: '',
      password: '',
    },
    validationSchema,
    onSubmit: async (values) => {
      await loginMutation({ variables: { input: values } });
    },
  });

  return (
    <VStack gap="$4">
      <Input
        label="Email"
        value={formik.values.email}
        onChangeText={formik.handleChange('email')}
        onBlur={formik.handleBlur('email')}
        error={formik.touched.email ? formik.errors.email : undefined}
        keyboardType="email-address"
        autoCapitalize="none"
      />

      <Input
        label="Password"
        value={formik.values.password}
        onChangeText={formik.handleChange('password')}
        onBlur={formik.handleBlur('password')}
        error={formik.touched.password ? formik.errors.password : undefined}
        secureTextEntry
      />

      <Button
        onPress={formik.handleSubmit}
        isDisabled={!formik.isValid || formik.isSubmitting}
        isLoading={formik.isSubmitting}
      >
        Login
      </Button>
    </VStack>
  );
};

Validation Schemas

Common Patterns

import * as yup from 'yup';

// Email
email: yup.string()
  .email('Invalid email address')
  .required('Email is required')

// Password with requirements
password: yup.string()
  .min(8, 'Must be at least 8 characters')
  .matches(/[a-z]/, 'Must contain lowercase letter')
  .matches(/[A-Z]/, 'Must contain uppercase letter')
  .matches(/[0-9]/, 'Must contain number')
  .required('Password is required')