Question

`从'react'导入React，{Component};

从'react-native'导入{StyleSheet，Platform，View，Image，Text，TextInput，TouchableOpacity，Alert，YellowBox，ListView};

const Realm = require（'realm'）;

让境界;

从'react-navigation'导入{StackNavigator};

类MainActivity扩展了Component {

static navigationOptions =
    {
        title: 'MyGPA',
    };

GoToSecondActivity = () =>
{
    this.props.navigation.navigate('Second');

};

constructor(){

    super();

    this.state = {

        Student_Name : '',

        Semester : '',


        GPA : ''

    };

    realm = new Realm({
        schema: [{name: 'CalcGP',
            properties:
                {
                    student_id: {type: 'int',   default: 0},
                    student_name: 'string',
                    semester: 'int',
                    gpa: 'double'
                }}]
    });

    YellowBox.ignoreWarnings([
        'Warning: componentWillMount is deprecated',
        'Warning: componentWillReceiveProps is deprecated',
        'Warning: isMounted(...) is deprecated', 'Module RCTImageLoader'
    ]);

}

add_Student=()=>{


    realm.write(() => {

        let ID = realm.objects('CalcGP').length + 1;

        realm.create('CalcGP', {
            student_id: ID,
            student_name: this.state.Student_Name,
            semester: this.state.Semester,
            gpa : this.state.GPA,

        });

    });
    Alert.alert("Details Added Successfully.");

};


render() {

    return (

        <View style={styles.MainContainer}>

            <TextInput
                placeholder="Enter Student Name"
                style = { styles.TextInputStyle }
                underlineColorAndroid = "transparent"
                onChangeText = { ( text ) => { this.setState({ Student_Name: text })} }
            />

            <TextInput
                placeholder="Enter Semester"
                style = { styles.TextInputStyle }
                underlineColorAndroid = "transparent"
                onChangeText = { ( text ) => { this.setState({ Semester: text })} }
            />

            <TextInput
                placeholder="Enter GPA"
                style = { styles.TextInputStyle }
                underlineColorAndroid = "transparent"
                onChangeText = { ( text ) => { this.setState({ GPA: text })} }
            />


            <TouchableOpacity onPress={this.add_Student} activeOpacity={0.7} style={styles.button} >

                <Text style={styles.TextStyle}> SAVE TO DATABASE </Text>

            </TouchableOpacity>



            <TouchableOpacity onPress={this.GoToSecondActivity} activeOpacity={0.7} style={styles.button} >

                <Text style={styles.TextStyle}> SHOW MY GPA </Text>

            </TouchableOpacity>

        </View>

    );
}

}

类ShowDataActivity扩展了Component { static navigationOptions = { 标题：'MyGPA'， };

constructor() {

    super();
    this.state = {

        Student_Name : '',

        Semester : '',


        GPA : ''

    };

    realm = new Realm({
        schema: [{name: 'CalcGP',
            properties:
                {
                    student_id: {type: 'int',   default: 0},
                    student_name: 'string',
                    semester: 'int',
                    gpa: 'double'
                }}]
    });

    YellowBox.ignoreWarnings([
        'Warning: componentWillMount is deprecated',
        'Warning: componentWillReceiveProps is deprecated',
        'Warning: isMounted(...) is deprecated', 'Module RCTImageLoader'
    ]);

    let mydata = realm.objects('CalcGP');

    let ds = new ListView.DataSource({rowHasChanged: (r1, r2) => r1 !== r2});

    this.state = {
        dataSource: ds.cloneWithRows(mydata),
    };

}

GoToEditActivity (student_id, student_name, semester, gpa) {

    this.props.navigation.navigate('Third', {

        ID : student_id,
        NAME : student_name,
        CLASS : semester,
        SUBJECT : gpa,

    });


}
dbtotal() {
    //allGP = realm.objects(GP);
    let cgpa = realm.objects('CalcGP').avg(gpa) ;
    Alert.alert(cgpa);
    //let tanDogs = dogs.filtered('color = "tan" AND name BEGINSWITH "B"');
}

ListViewItemSeparator = () => {
    return (
        <View
            style={{
                height: .5,
                width: "100%",
                backgroundColor: "#000",
            }}
        />
    );
};

render()
{
    return(

    <View style = { styles.MainContainer }>

        <ListView

            dataSource={this.state.dataSource}

            renderSeparator= {this.ListViewItemSeparator}

            renderRow={(rowData) => <View style={{flex:1, flexDirection: 'column'}} >

                <TouchableOpacity onPress={this.GoToEditActivity.bind(this, rowData.student_id, rowData.student_name, rowData.semester, rowData.gpa)} >

                    <Text style={styles.textViewContainer} >{'id = ' + rowData.student_id}</Text>

                    <Text style={styles.textViewContainer} >{'Name = ' + rowData.student_name}</Text>

                    <Text style={styles.textViewContainer} >{'Semester = ' + rowData.semester}</Text>

                    <Text style={styles.textViewContainer} >{'GPA = ' + rowData.gpa}</Text>

                </TouchableOpacity>


            </View> }

        />
        <TouchableOpacity onPress={this.dbtotal} activeOpacity={0.7} style={styles.button} >

            <Text style={styles.TextStyle}> CALCULATE </Text>

        </TouchableOpacity>
    </View>
    );
}

}

类EditActivity扩展了Component {

static navigationOptions =
    {
        title: 'EditActivity',
    };


constructor() {

    super();
    this.state = {

        Student_Id : '',

        Student_Name: '',

        Semester: '',

        GPA: ''

    };


    YellowBox.ignoreWarnings([
        'Warning: componentWillMount is deprecated',
        'Warning: componentWillReceiveProps is deprecated',
        'Warning: isMounted(...) is deprecated', 'Module RCTImageLoader'
    ]);

}






componentDidMount(){

    // Received Student Details Sent From Previous Activity and Set Into State.

    this.setState({
        Student_Id : this.props.navigation.state.params.ID,
        Student_Name: this.props.navigation.state.params.NAME,
        Semester: this.props.navigation.state.params.CLASS,
        GPA: this.props.navigation.state.params.SUBJECT
    })

}
Update_Student=()=>{

    realm.write(() => {

        const ID = this.state.Student_Id - 1;

        const obj = realm.objects('CalcGP');

        obj[ID].student_name = this.state.Student_Name;
        obj[ID].semester = this.state.Semester;
        obj[ID].gpa = this.state.GPA;

    });

    Alert.alert("GP Updated Successfully.")

};

Delete_Student=()=>{

    realm.write(() => {

        const ID = this.state.Student_Id - 1;

        realm.delete(realm.objects('CalcGP')[ID]);

    });

    Alert.alert("Record Deleted Successfully.");

    this.props.navigation.navigate('Show');

};
render() {

    return (

        <View style={styles.MainContainer}>

            <TextInput
                value={this.state.Student_Name}
                style = { styles.TextInputStyle }
                underlineColorAndroid = "transparent"
                onChangeText = { ( text ) => { this.setState({ Student_Name: text })} }
            />

            <TextInput
                value={this.state.Semester}
                style = { styles.TextInputStyle }
                underlineColorAndroid = "transparent"
                onChangeText = { ( text ) => { this.setState({ Semester: text })} }
            />

            <TextInput
                value={this.state.GPA}
                style = { styles.TextInputStyle }
                underlineColorAndroid = "transparent"
                onChangeText = { ( text ) => { this.setState({ GPA: text })} }
            />


            <TouchableOpacity onPress={this.Update_Student} activeOpacity={0.7} style={styles.button} >

                <Text style={styles.TextStyle}> CLICK HERE TO UPDATE GP DETAILS </Text>

            </TouchableOpacity>

            <TouchableOpacity  activeOpacity={0.7} style={styles.button} onPress={this.Delete_Student} >

                <Text style={styles.TextStyle}> CLICK HERE TO DELETE CURRENT RECORD </Text>

            </TouchableOpacity>

        </View>

    );
}

}

Answer 1

使用这部分代码：

<TextInput
    placeholder="Enter Semester"
    style = { styles.TextInputStyle }
    underlineColorAndroid = "transparent"
    onChangeText = { ( text ) => { this.setState({ Semester: Number(text) })} }
/>

CalcGP.semester必须是'number'类型，得到'string'（'1'）

1 个答案: