Rendering JSON data in react native - ruby-on-rails

I'm currently using my api to render all posts in JSON to react native. But I keep getting this undefined error. And sometimes the data just wont render. Can anyone give me any help on rendering this data in react native? And explain to me what i'm doing wrong? I'm pretty new with JSON. Thanks :)
Here is my JSON:
{"data":[{"id":"1","type":"posts","links":{"self":"https://example.com/posts/1"},"attributes":{"title":"Laughter Post","context":{}},"relationships":{"user":{"links":{"self":"https://example.com/posts/1/relationships/user","related":"https://example.com/posts/1/user"}}}}]}
And here is my react native code:
import React, { Component } from "react";
import { FlatList, StyleSheet, Text, View } from "react-native";
export default class App extends Component {
state = {
data: []
};
componentWillMount() {
this.fetchData();
}
fetchData = async () => {
const response = await fetch("https://example.com/posts.json");
const json = await response.json();
this.setState({ data: json.data });
};
render() {
return (
<View style={styles.container}>
<FlatList
data={this.state.data}
keyExtractor={item => item.toString()}
renderItem={({ item }) =>
<Text>
{`${item.title}`}
</Text>}
/>
</View>
);
}
}
const styles = StyleSheet.create({
container: {
marginTop: 15,
flex: 1,
justifyContent: "center",
alignItems: "center",
backgroundColor: "#F5FCFF"
}
});

It seems you are accessing title directly from the root, but it is inside key attributes
It should be
{`${item. attributes.title}`}
Or else if you can tell us the exact error, we can help you more regarding this issue.

Related

React Native NOT rendering data from database on IOS

I have problem with render data on IOS Simulator. Render is work properly on website, but on IOS I still got stuck on "Loading.." text.
Here is my code:
import React from 'react'
import { useState } from 'react';
import { useEffect } from 'react';
import { SafeAreaView, Text, View, StyleSheet, Image, Alert } from 'react-native';
import { Card } from 'react-native-paper'
import firebase from 'firebase'
import Button from '../components/Button'
import Background from '../components/Background'
import TopBar from '../components/TopBar'
export default function HomeScreen({ navigation }) {
const [data, setData] = useState([])
const sampleData = [{id:0, title:"One"}, {id:1, title: "Two"}]
useEffect(() =>
{
const donorsData = [];
firebase.database()
.ref("testdb")
.orderByChild("isDonor")
.equalTo(true)
.once("value")
.then((results) => {
results.forEach((snapshot) => {
donorsData.push(snapshot.val());
});
setData(donorsData);
});
}, [])
const card = data.length > 0
? data.map(item =>
{
return <Card key={item.uid} style={{ marginBottom: 20, borderRadius: 10, }}>
<Text>{item.name}</Text>
<Text>{item.description}</Text>
<Image src={item.photo}></Image>
</Card>
})
: <Text>Loading...</Text>
return (
<View style={styles.container}>
{card}
</View>
);
}
On website is everything ok Website Screen
But on IOS Simulator I got only Loading
IOS Screen
I tried a lot of solutions found here, but no one works with this case. I think is probably because iOS doesn't have data? When I put console log at to top of return, I got nothing.
This might be a race condition error. You shouldn't rely on the data being fetched within 1500ms.
If that doesn't work. Make sure your result from firebase is correct.
Maybe something like this?
const [data, setData] = useState([])
const fetchDonorData = () => {
firebase.database()
.ref("testdb")
.orderByChild("isDonor")
.equalTo(true)
.once("value")
.then((results) => {
console.log({result}) //Make sure the data looks the way you want it
const mappedResult = results?.map(snapshot => snapshot.val())
setData(mappedResult)
})
}
useEffect(() => {
fetchDonorData()
}, [])
const renderItem = ({item}) =>
<Card style={{ marginBottom: 20, borderRadius: 10, }}>
<Text>{item.name}</Text>
<Text>{item.description}</Text>
<Image src={item.photo}></Image>
</Card>
return (
<View style={styles.container}>
<FlatList
data={data}
renderItem={renderItem}
keyExtractor={({item}) => item.uid}
ListEmptyComponent={<Text>Loading...</Text>}
/>
</View>
)

Rendering user post JSON data in react native

Hello i'm currently working with React native using my rails api to retrieve user micropost data. The data renders in my log but comes up blank in react native. Honestly not sure what i'm doing wrong. can anyone help? Maybe the JSON is the problem?
Here is the JSON data:
[{"id":4,"content":"fool","user_id":1,"created_at":"2018-06-21T00:50:08.343Z","updated_at":"2018-06-21T00:50:08.343Z","picture":{"url":null}},{"id":3,"content":"pool\r\n","user_id":1,"created_at":"2018-06-21T00:50:04.644Z","updated_at":"2018-06-21T00:50:04.644Z","picture":{"url":null}},{"id":2,"content":"cool","user_id":1,"created_at":"2018-06-16T04:26:11.020Z","updated_at":"2018-06-16T04:26:11.020Z","picture":{"url":null}}]
And Here is my React Native code:
import React, { Component } from "react";
import { FlatList, StyleSheet, Text, View, AsyncStorage } from "react-
native";
const ACCESS_TOKEN = 'access_token';
export default class App extends Component {
state = {
data: []
};
componentWillMount() {
this.fetchData();
}
fetchData = async () => {
let accessToken = await AsyncStorage.getItem(ACCESS_TOKEN);
const response = await fetch("https://example.com/api/users/"+accessToken);
const json = await response.json();
this.setState({ data: json.data });
};
render() {
return (
<View style={styles.container}>
<FlatList
data={this.state.data}
keyExtractor={item => item.toString()}
renderItem={({ item }) =>
<Text>
//also tried {`${item.content}`}, didn't work
{`${item.microposts.content}`}
</Text>}
/>
</View>
);
}
}
const styles = StyleSheet.create({
container: {
marginTop: 15,
flex: 1,
justifyContent: "center",
alignItems: "center",
backgroundColor: "#F5FCFF"
}
});
Remove the extra }
Please optimize code by declaring renderItem as such
renderItem={({ item }) => <Text>{item.microposts && item.microposts.content}</Text>}

storing data on iOS device using react native

I am new to React Native and trying to create a simple iOS app. The app has a button on clicking which I need to store the timestamp of the click on the device in a file.
I know that React Native has an API called AsyncStorage but I am getting errors while using this. I copied the code from some site on the net.
Can someone please guide me to use this API?
This is my entire code:
import React, {Component} from 'react';
import { StyleSheet, Text, View, TextInput, AsyncStorage } from 'react-native';
export default class App extends Component{
state = {
'name': ''
}
componentDidMount = () => AsyncStorage.getItem('name').then((value) => this.setState({'name': value}))
setName = (value) => {
AsyncStorage.setItem('name': value);
this.setState({'name': value});
}
render() {
return (
<View style={styles.container}>
<TextInput style = {styles.textInput} autoCapitalize = 'none'
onChangeText = {this.setName}/>
<Text>
{this.state.name}
</Text>
</View>
);
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
alignItems: 'center',
marginTop: 50
},
textInput: {
margin: 15,
height: 35,
borderWidth: 1,
backgroundColor: '#7685ed'
}
});
As for the error, when I launch the code on iOS, I am getting a red screen. There is no syntax error that I can see.
Thanks in advance.
Hard to say without more detail the exact problem you're facing, but I assume some of the following might help you?
Ah I see you posted some code. You will need a constructor that defines your state as well. Added it in my code below.
Please note I'm not an expert. Forgive any errors
import {
AsyncStorage,
} from 'react-native';
class myComponent extends React.Component{
constructor(props) {
super(props);
this.state = {
data: null
};
}
componentDidMount() {
this._loadInitialState().done();
}
_someFunction() {
var myData = 123;
saveItemLocally('data', myData);
}
async _loadInitialState() {
try {
// get localy stored data
var dataStored = await AsyncStorage.getItem('data');
if (dataStored!==null) {
this.setState({
data: dataStored
});
}
} catch (error) {
//didn't get locally stored data
console.log(error.message);
}
} // end _loadinitialstate
render () {
//your render function
return (
);
}
} // end of your component
async function saveItemLocally(item, value) {
try {
await AsyncStorage.setItem(item, value);
} catch (error) {
console.log('AsyncStorage error: ' + error.message);
}
}

React-Native/Expo Receiving ERROR 'null is not an object (evaluating 'match.localteam_name')

Here I am only running two API requests. The first one in the componentDidMount function works fine, but the second one labeled handleMatchFacts does not work. In short, Using React-Native I'm retrieving information from the API, mounting it to the page and then once the Touchablehighlight is clicked it is suppose to retrieve additional information from the API according to the 'id' that is passed in 'onPress'. I am able to console.log the json of the data in the second request, but for some reason when I setState with the new data and render it to the page in ListView, I get an error.
import React from 'react'
import { View, Text, StyleSheet, ListView, TouchableHighlight } from 'react-native'
export default class Main extends React.Component {
constructor() {
super();
const ds = new ListView.DataSource({rowHasChanged: (r1, r2) => r1 !== r2});
this.state = {
matches: ds.cloneWithRows([]),
matchFacts: ds.cloneWithRows([])
};
this.handleShowMatchFacts.bind(this)
}
componentDidMount(){
fetch("http://api.football-api.com/2.0/matches?match_date=27.04.2017&to_date=27.04.2017&Authorization=565ec012251f932ea4000001fa542ae9d994470e73fdb314a8a56d76")
.then(res => res.json())
.then(matches => {
this.setState({
matches : this.state.matches.cloneWithRows(matches)
})
})
}
handleShowMatchFacts = id => {
console.log('match', id)
return fetch(`http://api.football-api.com/2.0/matches/${id}?Authorization=565ec012251f932ea4000001fa542ae9d994470e73fdb314a8a56d76`)
.then(res => res.json())
.then(matchFacts => {
console.log('match facts', matchFacts)
let selectedMatch = matchFacts;
this.setState({
matches : this.state.matches.cloneWithRows([]),
matchFacts : this.state.matchFacts.cloneWithRows(selectedMatch)
})
})
}
render() {
return (
<View style={styles.mainContainer}>
<Text
style={styles.header}>
Todays Matches</Text>
<ListView
style={styles.matches}
dataSource={this.state.matches}
renderRow={(matches) =>
<TouchableHighlight
onPress={() => this.handleShowMatchFacts(matches.id)}
underlayColor="green"
><Text style={styles.item}> {matches.localteam_name} {matches.localteam_score} - {matches.visitorteam_score} {matches.visitorteam_name} </Text>
</TouchableHighlight>
}
/>
<ListView
style={styles.matches}
dataSource={this.state.matchFacts}
renderRow={(match) =>
<Text style={styles.item}> {match.localteam_name} {match.localteam_score} - {match.visitorteam_score} {match.visitorteam_name} </Text>
}
/>
</View>
);
}
}
const styles = StyleSheet.create({
mainContainer : {
flex: 1,
padding: 20
},
header : {
textAlign: 'center'
},
matches : {
marginTop: 20
},
item : {
borderRadius: 4,
borderWidth: 0.5,
borderColor: 'green',
marginBottom: 5,
padding: 20,
textAlign: 'center',
},
});
You're probably seeing an issue because the second API request doesn't return an array, it returns an object. The cloneWithRows expects an array. Replacing this line
matchFacts : this.state.matchFacts.cloneWithRows(selectedMatch)
with
matchFacts : this.state.matchFacts.cloneWithRows([selectedMatch])
may help, depending on how you render this new data.
That's just a guess since I don't know what error you're receiving.

When Using React Native, how do you save the results of a fetch?

I am currently in the process of writing an Android React Native app powered by a JSON api served via a Ruby on Rails server. My biggest snag currently has been saving the results of a fetch call. My code is as follows:
import React, { Component } from 'react';
import {
AppRegistry,
StyleSheet,
Text,
View,
TouchableHighlight,
Alert
} from 'react-native';
class MiniMinionClient extends Component {
constructor(props) {
super(props);
}
getStatus() {
return fetch('http://10.0.2.2:3000/api/v1/status.json')
.then((response) => response.json())
.then((responseJson) => {
return responseJson;
})
.catch((error) => {
console.error(error);
});
}
render() {
var status = this.getStatus()
return (
<View style={styles.container}>
<Text>Version {status.version}</Text>
<Text>Last Update: {status.last_update}</Text>
</View>
);
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
flexDirection: 'row',
justifyContent: 'center',
alignItems: 'center',
backgroundColor: '#F5FCFF',
}
});
AppRegistry.registerComponent('MiniMinionClient', () => MiniMinionClient);
I do know this is a valid endpoint, as I was able to make the same call work if I use alert posts, which I got the idea from here. I think the issue stems from the asynchronous nature of fetch but I am not sure how to get around this.
Any help would be much appreciated!
Here is one of the way to save and access the result of your api calls. The best way to call your api is from componentWillMount lifecycle. This lifecycle is called just before the Component is rendered.
You can either use your api call directly on componentWillMount() or call the getStatus() function you created.
import React, { Component } from 'react';
import {
AppRegistry,
StyleSheet,
Text,
View,
TouchableHighlight,
Alert
} from 'react-native';
class MiniMinionClient extends Component {
constructor(props) {
super(props);
// Initialize empty state here
this.state = {
version: '',
last_update: ''
};
}
componentWillMount() {
// It's best to use your api call on componentWillMount
this.getStatus();
}
getStatus() {
fetch('http://10.0.2.2:3000/api/v1/status.json')
.then((response) => response.json())
.then((responseJson) => {
// set the state of the output here
this.setState({
version: responseJson.version,
last_update: responseJson.last_update
});
})
.catch((error) => {
console.error(error);
});
}
render() {
return (
<View style={styles.container}>
{/*You can now access the values using this.state here*/}
<Text>Version {this.state.version}</Text>
<Text>Last Update: {this.state.last_update}</Text>
</View>
);
}
}
const styles = StyleSheet.create({
container: {
flex: 1,
flexDirection: 'row',
justifyContent: 'center',
alignItems: 'center',
backgroundColor: '#F5FCFF',
}
});
AppRegistry.registerComponent('MiniMinionClient', () => MiniMinionClient);

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