Firestore+Rreact.js如何通过从用户过滤来从集合中获取文档

Question

我有三个数据字段，默认情况下，在构造函数中，它们都设置为all。ı想要做的是像在mysql中一样对这些字段进行多次查询。例如：field1是苹果，field2是橙色，并且ı不要触摸field3。(顺便说一句，Tumu的意思是"所有"。(这是我的代码：

class Kurumlar extends Component {
constructor(props) {
super(props);
this.state = {
data: [],
isLoading: true,
page: 1,
HizmetTuru: "Tumu",
HizmetAlani: "Tumu",
Ucretlendirme: "Tumu"
};
}
handleChange = e => {
this.setState({
[e.target.name]: e.target.value
}, console.log(this.state));
}

componentDidMount() {
const db = firebase.firestore();
let docs = db.collection("Paydaslar")
console.log(this.state)
//docs = db.collection("Paydaslar").where("HizmetTuru", "==", this.state.HizmetTuru);
docs.get()
.then(snapshot => {
let data = [];
snapshot.forEach(doc => {
if (doc.data().isVisible) {
data.push(doc.data());
}
});
this.setState({ data, isLoading: false });
})
.catch(err => {
console.log("Error getting documents", err);
});
}
componentDidUpdate(){
const db = firebase.firestore();
let docs = db.collection("Paydaslar")
if(this.state.HizmetTuru != "Tumu"){docs=db.collection("Paydaslar").where("HizmetTuru", "==", this.state.HizmetTuru)}
if(this.state.HizmetAlani != "Tumu"){docs=db.collection("Paydaslar").where("HizmetAlani", "==", this.state.HizmetAlani)}
if(this.state.Ucretlendirme != "Tumu"){docs=db.collection("Paydaslar").where("Ucretlendirme", "==", this.state.Ucretlendirme)}

docs.get()
.then(snapshot => {
let data = [];
snapshot.forEach(doc => {
if (doc.data().isVisible) {
data.push(doc.data());
}
});
this.setState({ data, isLoading: false });
})
.catch(err => {
console.log("Error getting documents", err);
});
}

通过这种方式，如果将1个字段设置为一个值(与所有字段不同(代码中的Tumu(，则其他字段不起作用。

Answer 1

如果我理解正确，您希望构建一个具有多种可能条件的查询，这取决于用户选择的条件。

在这种情况下，您可以使用构建器模式：

const db = firebase.firestore();
let query = db.collection("Paydaslar").collection("Paydaslar")
if(this.state.HizmetTuru != "Tumu") {
query = query.where("HizmetTuru", "==", this.state.HizmetTuru)
}
if(this.state.HizmetAlani != "Tumu") {
query = query.where("HizmetAlani", "==", this.state.HizmetAlani)
}
if(this.state.Ucretlendirme != "Tumu"){
query = query.where("Ucretlendirme", "==", this.state.Ucretlendirme)
}
docs.get()
...

Answer 2

我只是在if部分找到了它，do：

if (this.state.HizmetTuru != "Tumu") { docs = docs.where("HizmetTuru", "==", this.state.HizmetTuru) }
if (this.state.HizmetAlani != "Tumu") { docs = docs.where("HizmetAlani", "==", this.state.HizmetAlani) }
if (this.state.Ucretlendirme != "Tumu") { docs = docs.where("Ucretlendirme", "==", this.state.Ucretlendirme) }