我的应用程序下拉菜单非常慢。如果我进入设置屏幕并尝试更改我的专业，这需要很长时间。或者在此特定屏幕中添加或编辑专业的任何事情。我真的需要更快地添加或编辑专业。我不确定编辑或添加专业的原因是否需要太长时间。而且我不确定如何更快地添加和编辑专业。所以我发布了整个组件，我正在评论处理添加或编辑专业的部分。我正在使用react-native-material-dropdown。 这是整个组件代码：
import React from 'react';
import PropTypes from 'prop-types';
import { View, ScrollView, Text, TouchableOpacity } from 'react-native';
import { connect } from 'react-redux';
import { compose, withStateHandlers } from 'recompose';
import { Dropdown } from 'react-native-material-dropdown';
import { Icon } from 'react-native-material-ui';
import R from 'ramda';
import { ConnectivityRenderer } from 'react-native-offline';
import NetworkConnectivity from '../error/NetworkConnectivity';
import { toArray } from '../selectors';
import { Container, Switch, SwitchOption } from './common';
import { editStudent } from '../actions';
const propTypes = {
toolbar: PropTypes.elem,
loading: PropTypes.bool,
university: PropTypes.shape({
id: PropTypes.string,
name: PropTypes.string,
}),
universities: PropTypes.arrayOf(
PropTypes.shape({
id: PropTypes.string,
name: PropTypes.string,
})
),
degrees: PropTypes.arrayOf(
PropTypes.shape({
id: PropTypes.string,
name: PropTypes.string,
})
),
studentDegrees: PropTypes.arrayOf(
PropTypes.shape({
index: PropTypes.number,
track: PropTypes.string,
})
),
errors: PropTypes.shape({
university: PropTypes.string,
degree: PropTypes.string,
}),
year: PropTypes.string,
onUniversityChange: PropTypes.func,
onTermChange: PropTypes.func,
onDegreeChange: PropTypes.func,
onYearChange: PropTypes.func,
onTrackChange: PropTypes.func,
onAddDegree: PropTypes.func,
onDone: PropTypes.func,
};
const contextTypes = {
uiTheme: PropTypes.object.isRequired,
};
const validate = state => {
const result = {};
if (!state.university.id) {
result.university = 'You should select an university';
}
return result;
};
const enhance = compose(
connect(
({ user, universities, degrees }) => ({
studentId: user.id,
user,
universities: toArray(universities),
degrees: toArray(degrees),
}),
{ editStudent }
),
withStateHandlers(
props => {
return {
university: props.user.university || {},
year: props.user.academicClass || 'freshman',
studentDegrees: R.isEmpty(props.degrees)
? []
: R.isEmpty(props.user.studentDegrees)
? [{ degree_id: props.degrees[0].id, track: 'Major' }]
: R.values(props.user.studentDegrees),
errors: {},
};
},
{
onUniversityChange: () => (value, index, data) => ({
university: data[index],
}),
onYearChange: () => year => ({ year }),
onTrackChange: state => ({ idx, track }) => ({
studentDegrees: R.update(
idx,
R.assoc('track', track, state.studentDegrees[idx]),
state.studentDegrees
),
}),
// Fucntion dealing with degree change
onDegreeChange: (state, props) => ({ idx, index }) => ({
studentDegrees: R.update(
idx,
R.assoc(
'degree_id',
props.degrees[index].id,
state.studentDegrees[idx]
),
state.studentDegrees
),
}),
// Function dealing with degree adding
onAddDegree: (state, props) => () => ({
studentDegrees: R.append(
{
degree_id: props.degrees[0].id,
track: 'Major',
},
state.studentDegrees
),
}),
onRemoveDegree: state => idx => ({
studentDegrees: [
...state.studentDegrees.slice(0, idx),
...state.studentDegrees.slice(idx + 1),
],
}),
// When the user is done with settings.
// This function communicates with the back end to save things in the remote database
onDone: (state, { studentId, editStudent }) => () => {
const errors = validate(state);
if (Object.keys(errors).length !== 0) {
return { errors };
}
editStudent(
studentId,
state.year,
state.university.id,
state.studentDegrees
);
},
}
)
);
// The Settings Component
const FormUserSettings = (props, context) => {
const styles = getStyles(props, context);
return (
<ConnectivityRenderer>
{isConnected => (
isConnected ? (
<Container>
{React.cloneElement(props.toolbar, {
onRightElementPress: props.onDone,
})}
<ScrollView style={styles.container}>
<Text
style={[
styles.title,
props.errors.university ? styles.titleError : {},
]}
>
University
</Text>
// Selecting a university
<Dropdown
label="Select university..."
data={props.universities.map(u => ({ id: u.id, value: u.name }))}
onChangeText={props.onUniversityChange}
value={props.university.name}
/>
{props.errors.university &&
<Text style={styles.errorMessage}>
{props.errors.university}
</Text>}
<View style={{ height: 16 }} />
<Text style={styles.title}>Current Year</Text>
<View style={{ height: 8 }} />
<Switch
value={props.year}
onChange={props.onYearChange}
selectedColor={styles.switchSelectedColor}
unselectedColor={styles.switchUnselectedColor}
>
<SwitchOption text="Freshman" value="freshman" />
<SwitchOption text="Sophomore" value="sophomore" />
<SwitchOption text="Junior" value="junior" />
<SwitchOption text="Senior" value="senior" />
</Switch>
<View style={{ height: 16 }} />
<Text
style={[styles.title, props.errors.degree ? styles.titleError : {}]}
>
Major / Minors
</Text>
{!R.isEmpty(props.degrees) &&
props.studentDegrees.map((sd, idx) => {
const degree = R.find(R.propEq('id', sd.degree_id), props.degrees);
return (
<View
key={`sd-${idx}`}
style={{ flex: 1, height: 96, marginTop: 24 }}
>
<View
style={{
flex: 1,
flexDirection: 'row',
alignItems: 'flex-end',
}}
>
<View style={{ flex: 1 }}>
<Dropdown
style={{ flex: 1 }}
label="Select degree..."
data={props.degrees.map(d => ({
id: d.id,
value: d.name,
}))}
onChangeText={(value, index) =>
props.onDegreeChange({ idx, index })}
value={degree ? degree.name : ''}
/>
</View>
{props.studentDegrees.length !== 1 &&
<TouchableOpacity
style={{ marginBottom: 8, paddingLeft: 24 }}
onPress={() => props.onRemoveDegree(idx)}
>
<Icon name="delete" size={24} />
</TouchableOpacity>}
</View>
<Switch
value={sd.track}
onChange={track => props.onTrackChange({ idx, track })}
selectedColor={styles.switchSelectedColor}
unselectedColor={styles.switchUnselectedColor}
>
<SwitchOption text="Major" value="Major" />
<SwitchOption text="Minor" value="Minor" />
<SwitchOption text="Certificate" value="Cert" />
</Switch>
</View>
);
})}
<TouchableOpacity style={{ padding: 10 }} onPress={props.onAddDegree}>
<Text style={styles.addDegreeText}>+ Degree</Text>
</TouchableOpacity>
</ScrollView>
</Container>
) : (
<Container>
{React.cloneElement(props.toolbar, {
onRightElementPress: props.onDone,
})}
<NetworkConnectivity />
<ScrollView style={styles.container}>
<Text
style={[
styles.titleDisabled,
props.errors.university ? styles.titleError : {},
]}
>
University
</Text>
<Dropdown
label=""
data={props.universities.map(u => ({ id: u.id, value: u.name }))}
onChangeText={props.onUniversityChange}
value={props.university.name}
disabled={true}
editable={false}
/>
{props.errors.university &&
<Text style={styles.errorMessage}>
{props.errors.university}
</Text>}
<View style={{ height: 16 }} />
<Text style={styles.titleDisabled}>Current Year</Text>
<View style={{ height: 8 }} />
<Switch
value={props.year}
onChange={props.onYearChange}
selectedColor={styles.disabledSwitchSelectedColor}
unselectedColor={styles.switchUnselectedColor}
>
<SwitchOption text="Freshman" value="freshman" />
<SwitchOption text="Sophomore" value="sophomore" />
<SwitchOption text="Junior" value="junior" />
<SwitchOption text="Senior" value="senior" />
</Switch>
<View style={{ height: 16 }} />
<Text
style={[styles.titleDisabled, props.errors.degree ? styles.titleError : {}]}
>
Major / Minors
</Text>
// The problem of slowness starts here
// I feel like something here should be improved
{!R.isEmpty(props.degrees) &&
props.studentDegrees.map((sd, idx) => {
const degree = R.find(R.propEq('id', sd.degree_id), props.degrees);
return (
<View
key={`sd-${idx}`}
style={{ flex: 1, height: 96, marginTop: 24 }}
>
<View
style={{
flex: 1,
flexDirection: 'row',
alignItems: 'flex-end',
}}
>
<View style={{ flex: 1 }}>
<Dropdown
style={{ flex: 1 }}
label="Select degree..."
data={props.degrees.map(d => ({
id: d.id,
value: d.name,
}))}
disabled={true}
editable={false}
onChangeText={(value, index) =>
props.onDegreeChange({ idx, index })}
value={degree ? degree.name : ''}
/>
</View>
</View>
<Switch
value={sd.track}
onChange={track => props.onTrackChange({ idx, track })}
selectedColor={styles.disabledSwitchSelectedColor}
unselectedColor={styles.switchUnselectedColor}
>
<SwitchOption text="Major" value="Major" />
<SwitchOption text="Minor" value="Minor" />
<SwitchOption text="Certificate" value="Cert" />
</Switch>
</View>
);
})}
<TouchableOpacity disabled={true} style={{ padding: 10 }} onPress={props.onAddDegree} disabled={true}>
<Text style={styles.addDegreeTextDisabled}>+ Degree</Text>
</TouchableOpacity>
</ScrollView>
</Container>
)
)}
</ConnectivityRenderer>
);
};
FormUserSettings.contextTypes = contextTypes;
FormUserSettings.propTypes = propTypes;
export default enhance(FormUserSettings);