A example of Mutation using Relay Modern and React Native

RegisterScreen.js

// @flow
import React, { PureComponent } from 'react'
import { View, Text, TextInput, TouchableOpacity } from 'react-native'
import { commitMutation, graphql } from 'react-relay'
import environment from './createRelayEnvironment'
import style from './RegisterScreen.style'

/**
 * In Relay Modern a name pattern are used in Mutations or Queries, as example below:
 * `ComponentName__MutationName__Mutation(...`
 */

const mutation = graphql`
  mutation RegisterScreen__RegisterEmail__Mutation(
    $input: RegisterEmailInput!
  ) {
    RegisterEmail(input: $input) {
      token
      error
    }
  }
`

class RegisterScreen extends PureComponent {

  static navigationOptions = {
    header: null,
    gesturesEnabled: false
  }

  state = {
    name: null,
    email: null,
    password: null
  }

  constructor() {
    super()
    this.doRegister = this.doRegister.bind(this)
  }  

  RegisterEmailMutationSuccess({ RegisterEmail }) {
    const { token, error } = RegisterEmail
    // Successful. Go to the party o/
  }

  RegisterEmailMutationError(error) {
    // You can use a more sofisticated error logger :)
    console.error('RegisterEmailMutation ::Error', error)
  }

  doRegister() {
    const { name, email, password } = this.state

    const variables = {
      input: {
        name,
        email,
        password
      },
    }

    commitMutation(
      environment,
      {
        mutation,
        variables,
        onCompleted: res => this.RegisterEmailMutationSuccess(res),
        onError: err => this.RegisterEmailMutationError(err),
      },
    )
  }

  render() {
    const { name, email, password } = this.state

    return (
      <View style={style.container}>
        <TextInput value={name}
          onChangeText={(name) => this.setState({ name })}
        />

        <TextInput value={email}
          onChangeText={(email) => this.setState({ email })}
        />

        <TextInput value={password}
          secureTextEntry={true}
          onChangeText={(password) => this.setState({ password })}
        />

        <TouchableOpacity onPress={this.doRegister}>
          <Text>Register</Text>
        </TochableOpacity>
      </View>
    )
  }
}

export default RegisterScreen