我有两个看起来像这样的对象：
class Field extends RESTModel {
int id;
String name;
String dataType;
int objectId;
}
class FieldKeywordMap extends RESTModel {
int id;
String keywordName;
int objectConfigurationId;
int fieldId;
}
我有一个名为 _fieldKeywordMaps 的 FieldKeywordMap 列表和一个名为 _selectedFields 的字段列表。我正在编写一个函数来返回基于 2 个条件的 _fieldKeywordMaps 的过滤版本：
基于第一个条件的过滤有效，但我无法确定如何遍历我的 _selectedFields 列表并将其与 _fieldKeywordMaps 中的对象进行比较。代码如下：
selectObjectKeywordMaps() async {
if (selectedObjectConfiguration() != null && selectedObject() != null) {
List<FieldKeywordMap> _maps = _fieldKeywordMaps
.where((keywordMap) =>
keywordMap.objectConfigurationId == selectedObjectConfiguration().id)
.where((filteredKeywordMap) =>
_selectedFields.map((field) => field.id).contains(filteredKeywordMap.id))
.toList();
_selectedObjectKeywordMaps = _maps.toList();
fetchAffectedCustomers();
} else {
_selectedObjectKeywordMaps = [];
}
notifyListeners();
}
答案 0 :(得分：1)
.where((filteredKeywordMap) => _selectedFields.map(...)) 不合适。 Iterable.map 用于执行从一个 Iterable 到另一个 .where((filteredKeywordMap) => _selectedFields.any((field) => field.id == filteredKeywordMap.fieldId)) 的 1:1 转换。
你可以这样做：
_selectedFields
请注意，这可能效率低下；使 Map 从 ids 到 Fields 而不是 List<Field>s 的 class MainSection extends Component {
state = {
data: null,
filteredData: null,
loading: true,
filterLanguages: null,
slideText: false,
currentFilter: 'All'
}
async componentDidMount() {
try {
// eslint-disable-next-line no-unused-vars
const resp = await axios
.get("https://backendkham.herokuapp.com/api/show")
.then((response) => {
const finalLangs = ["All"];
const languages = response.data.data.forEach((element) => {
element.repos.forEach((repo) => {
// console.log(repo.languages)
finalLangs.push(repo.languages);
});
});
const validData = response.data.data.filter(
(user) => user.repos.length > 0
);
this.setState(prevState => ({
...prevState,
data: [...validData],
filteredData: [...validData],
loading: false,
filterLanguages: [...new Set(finalLangs)].filter((item) => item)
}))
});
} catch (error) {
console.log(error);
return Promise.reject(error);
}
}
render() {
const filterRepos = (lang) => {
// console.log(lang)
if (lang === "All") {
this.setState(prevState => ({
filteredData: prevState.data
}))
} else {
const dataToBeFiltered = [...this.state.data].map((obj) => {
// console.log(obj.repos);
obj.repos = obj.repos.filter((repo) => repo.languages === lang);
// console.log(obj.repos);
return obj;
});
this.setState(prevState => ({
...prevState,
filteredData: dataToBeFiltered
}))
console.table(this.state);
// console.log(filteredData);
// console.log(dataToBeFiltered);
}
};
const newFilter = (repoLang) => {
this.setState(prevState => ({
...prevState,
currentFilter: repoLang
}))
}
const animateFilterOptions = () => {
this.setState(prevState => ({
...prevState,
slideText: !prevState.slideText
}))
}
if (this.state.loading) {
return (
<Loader
className={classes.Loader}
type="TailSpin"
color="#00BFFF"
height={100}
width={100} //3 secs
/>
);
}
if (this.state.data) {
// console.log('filter languages are:', typeof(filterLanguages[0]));
// console.log('data in render method:', data)
return (
<>
<Filter
filterRepos={(event) => filterRepos(event.target.value)}
slideText={this.state.slideText}
btnClick={animateFilterOptions}
languages={this.state.filterLanguages}
/>
<div className={classes.Main}>
<Cards data={this.state.filteredData} />
</div>
</>
);
}
}
};
将使查找更快更简单。