🥖 🌳 🆎 DataStore - CRUD (Create Read Update Delete) ❓ 🛀🏽 🍷

Auf Wiedersehen Redux, MobX, Apollo! Die Linie zwischen Backend und Frontend ist unterbrochen! Ein innovativer Schritt in der Entwicklung staatlicher Manager.

Datenspeicher

Eine der schwierigsten Aufgaben bei der Entwicklung von Web- und Mobilanwendungen besteht darin, Daten zwischen Geräten zu synchronisieren und Offline-Vorgänge auszuführen. Wenn das Gerät offline ist, sollten Ihre Kunden Ihre Anwendung im Idealfall weiterhin verwenden können, um nicht nur auf Daten zuzugreifen, sondern diese auch zu erstellen und zu ändern. Wenn das Gerät wieder online ist, muss die Anwendung erneut eine Verbindung zum Backend herstellen, die Daten synchronisieren und etwaige Konflikte lösen. Die korrekte Behandlung aller Extremfälle erfordert viel undifferenzierten Code, selbst wenn der AWS AppSync SDK-Cache auf einem Gerät mit autonomen Mutationen und Delta-Synchronisation verwendet wird.

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1. Real time

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web sockets?

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, fullStack serverless AWS Amplify, real time , , , , GraphQL . , , , AWS Amplify Store:

type Job
  @model
  @auth(
    rules: [
      {allow: owner, ownerField: "owner", operations: [create, update, delete]},
    ])
{
  id: ID!
  position: String!
  rate: String!
  description: String!
  owner: String
}

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fetch axios?

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npm run amplify-modelgen

models .

graphql , Flow, TS JavaScript.

3. Offline data & cloud sync

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git clone https://github.com/fullstackserverless/startup.git

cd startup

Install dependencies

yarn

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All resources are updated in the cloud

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npx amplify-app@latest

React Native Cli,

yarn add @aws-amplify/datastore @react-native-community/netinfo @react-native-community/async-storage

React Native> 0.60, iOS:

cd ios && pod install && cd ..

API(App Sync)

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, API

amplify add api

GraphQL amplify/backend/api/<datasourcename>/schema.graphql :

type Job
  @model
  @auth(
    rules: [
      {allow: owner, ownerField: "owner", operations: [create, update, delete]},
    ])
{
  id: ID!
  position: String!
  rate: String!
  description: String!
  owner: String
}

, DataStore, — . GraphQL JavaScript, iOS Android , . GraphQL , Automerge AppSync. NPX Amplify CLI.

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npm run amplify-modelgen

src/models

API

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amplify push

All resources are updated in the cloud

READ

JobsMain src/screens/Jobs/JobsMain.js

Query, , useQuery , Flatlist.

import React, { useEffect, useState } from 'react'
import { FlatList } from 'react-native'
import { Auth } from 'aws-amplify'
import { AppContainer, CardVacancies, Space, Header } from 'react-native-unicorn-uikit'
import { DataStore } from '@aws-amplify/datastore'
import { Job } from '../../models'
import { goBack, onScreen } from '../../constants'

const JobsMain = ({ navigation }) => {
  const [data, updateJobs] = useState([])

  const fetchJobs = async () => {
    const mess = await DataStore.query(Job)
    updateJobs(mess)
  }

  useEffect(() => {
    fetchJobs()
    const subscription = DataStore.observe(Job).subscribe(() => fetchJobs())
    return () => {
      subscription.unsubscribe()
    }
  }, [data])

  const _renderItem = ({ item }) => {
    const owner = Auth.user.attributes.sub
    const check = owner === item.owner
    return (
      <>
        <CardVacancies obj={item} onPress={onScreen(check ? 'JOB_ADD' : 'JOB_DETAIL', navigation, item)} />
        <Space height={20} />
      </>
    )
  }

  const _keyExtractor = (obj) => obj.id.toString()

  return (
    <AppContainer onPress={goBack(navigation)} flatlist>
      <FlatList
        scrollEventThrottle={16}
        data={data}
        renderItem={_renderItem}
        keyExtractor={_keyExtractor}
        onEndReachedThreshold={0.5}
        ListHeaderComponent={
          <Header
            onPress={goBack(navigation)}
            onPressRight={onScreen('JOB_ADD', navigation)}
            iconLeft="angle-dobule-left"
            iconRight="plus-a"
          />
        }
        stickyHeaderIndices={[0]}
      />
    </AppContainer>
  )
}

export { JobsMain }

JobDetail src/screens/Jobs/JobDetail.js

import React from 'react'
import { Platform } from 'react-native'
import { AppContainer, CardVacancies, Space, Header } from 'react-native-unicorn-uikit'
import { goBack } from '../../constants'

const JobDetail = ({ route, navigation }) => {
  return (
    <AppContainer>
      <Header onPress={goBack(navigation)} iconLeft="angle-dobule-left" />
      <CardVacancies obj={route.params} detail />
      <Space height={Platform.OS === 'ios' ? 100 : 30} />
    </AppContainer>
  )
}

export { JobDetail }

CREATE UPDATE DELETE

JobAdd src/screens/Jobs/JobAdd.js, CREATE UPDATE DELETE

import React, { useState, useEffect, useRef } from 'react'
import { AppContainer, Input, Space, Button, Header, ButtonLink } from 'react-native-unicorn-uikit'
import { DataStore } from '@aws-amplify/datastore'
import { Formik } from 'formik'
import * as Yup from 'yup'
import { Job } from '../../models'
import { goBack } from '../../constants'

const JobAdd = ({ route, navigation }) => {
  const [loading, setLoading] = useState(false)
  const [check, setOwner] = useState(false)
  const [error, setError] = useState('')

  const [input, setJob] = useState({
    id: '',
    position: '',
    rate: '',
    description: ''
  })

  const formikRef = useRef()

  useEffect(() => {
    const obj = route.params
    if (typeof obj !== 'undefined') {
      setOwner(true)
      setJob(obj)
      const { setFieldValue } = formikRef.current
      const { position, rate, description } = obj
      setFieldValue('position', position)
      setFieldValue('rate', rate)
      setFieldValue('description', description)
    }
  }, [route.params])

  const createJob = async (values) => (await DataStore.save(new Job({ ...values }))) && goBack(navigation)()

  const updateJob = async ({ position, rate, description }) => {
    try {
      setLoading(true)
      const original = await DataStore.query(Job, input.id)
      const update = await DataStore.save(
        Job.copyOf(original, (updated) => {
          updated.position = position
          updated.rate = rate
          updated.description = description
        })
      )
      update && goBack(navigation)()
      setLoading(false)
    } catch (err) {
      setError(err)
    }
  }

  const deleteJob = async () => {
    try {
      setLoading(true)
      const job = await DataStore.query(Job, input.id)
      const del = await DataStore.delete(job)
      del && goBack(navigation)()
      setLoading(false)
    } catch (err) {
      setError(err)
    }
  }

  return (
    <AppContainer onPress={goBack(navigation)} loading={loading} error={error}>
      <Header onPress={goBack(navigation)} iconLeft="angle-dobule-left" />
      <Space height={20} />
      <Formik
        innerRef={formikRef}
        initialValues={input}
        onSubmit={(values) => (check ? updateJob(values) : createJob(values))}
        validationSchema={Yup.object().shape({
          position: Yup.string().min(3).required(),
          rate: Yup.string().min(3).required(),
          description: Yup.string().min(3).required()
        })}
      >
        {({ values, handleChange, errors, setFieldTouched, touched, isValid, handleSubmit }) => (
          <>
            <Input
              name="position"
              value={values.position}
              onChangeText={handleChange('position')}
              onBlur={() => setFieldTouched('position')}
              placeholder="Position"
              touched={touched}
              errors={errors}
            />
            <Input
              name="rate"
              keyboardType="numeric"
              value={`${values.rate}`}
              onChangeText={handleChange('rate')}
              onBlur={() => setFieldTouched('rate')}
              placeholder="Rate"
              touched={touched}
              errors={errors}
            />
            <Input
              name="description"
              value={values.description}
              onChangeText={handleChange('description')}
              onBlur={() => setFieldTouched('description')}
              placeholder="Description"
              touched={touched}
              errors={errors}
              multiline
              numberOfLines={5}
            />
            <Space height={40} />
            <Button title={check ? 'Update' : 'Create'} disabled={!isValid} onPress={handleSubmit} formik />
            {check && (
              <>
                <Space height={10} />
                <ButtonLink title="or" textStyle={{ alignSelf: 'center' }} />
                <Space height={15} />
                <Button title="DELETE" onPress={deleteJob} cancel />
              </>
            )}
          </>
        )}
      </Formik>
      <Space height={100} />
    </AppContainer>
  )
}

export { JobAdd }

screens/Jobs/index.js

export * from './JobsMain'
export * from './JobDetail'
export * from './JobAdd'

Jobs StackNavigator

import * as React from 'react'
import { createStackNavigator } from '@react-navigation/stack'
import { enableScreens } from 'react-native-screens' // eslint-disable-line
import { Hello, SignUp, SignIn, ConfirmSignUp, User, Forgot, ForgotPassSubmit } from './screens/Authenticator'
import { JobsMain, JobDetail, JobAdd } from './screens/Jobs'

enableScreens()

const Stack = createStackNavigator()

const AppNavigator = () => {
  return (
    <Stack.Navigator
      screenOptions={{
        headerShown: false
      }}
      initialRouteName="HELLO"
    >
      <Stack.Screen name="HELLO" component={Hello} />
      <Stack.Screen name="SIGN_UP" component={SignUp} />
      <Stack.Screen name="SIGN_IN" component={SignIn} />
      <Stack.Screen name="FORGOT" component={Forgot} />
      <Stack.Screen name="FORGOT_PASSWORD_SUBMIT" component={ForgotPassSubmit} />
      <Stack.Screen name="CONFIRM_SIGN_UP" component={ConfirmSignUp} />
      <Stack.Screen name="USER" component={User} />
      <Stack.Screen name="JOBS_MAIN" component={JobsMain} />
      <Stack.Screen name="JOB_DETAIL" component={JobDetail} />
      <Stack.Screen name="JOB_ADD" component={JobAdd} />
    </Stack.Navigator>
  )
}

export default AppNavigator

Jobs

User screens/Authenticator/User/index.js

import React, { useState, useEffect } from 'react'
import { Auth } from 'aws-amplify'
import * as Keychain from 'react-native-keychain'
import { AppContainer, Button } from 'react-native-unicorn-uikit'
import { goHome, onScreen } from '../../../constants'

const User = ({ navigation }) => {
  const [loading, setLoading] = useState(false)
  const [error, setError] = useState('')

  useEffect(() => {
    const checkUser = async () => {
      await Auth.currentAuthenticatedUser()
    }
    checkUser()
  })

  const _onPress = async () => {
    setLoading(true)
    try {
      await Auth.signOut()
      await Keychain.resetInternetCredentials('auth')
      goHome(navigation)()
    } catch (err) {
      setError(err.message)
    }
  }

  const _onPressJob = () => onScreen('JOBS_MAIN', navigation)() //    JOBS_MAIN

  return (
    <AppContainer message={error} loading={loading}>
      <Button title="Sign Out" onPress={_onPress} />
      <Button title="Jobs" onPress={_onPressJob} />
    </AppContainer>
  )
}

export { User }