Firebase Firestore - 比较来自 2 个集合的数据

Question

我的 firebase 数据库有问题。我希望能够检索和比较 2 个不同集合的内容。在这种情况下，我想检查用户的答案是否与另一个集合中的答案键的答案相同。问题是我认为查询是异步完成的，所以我无法将值保存在 docRef.get() 函数之外。提前感谢您的帮助。

下面是我得到用户答案的​​地方：

firebase.auth().onAuthStateChanged((user) => {
         if (user) {
             var uid = user.uid;
             document.getElementById("useruser").innerHTML = user.displayName;

              var docRef = db.collection("Quiz").doc(user.displayName);
              docRef.get().then(function(doc) {
                    if (doc.exists) {
                       console.log("Document data:", doc.data());
                       document.getElementById("question1_1").innerHTML = doc.data().Question; //Here I have my user's answer
                       document.getElementById("reponse1_1_1").innerHTML = doc.data().Reponse1;
                       var lisetRep = doc.data().Reponse1;
                       document.getElementById("reponse1_1_2").innerHTML = doc.data().Reponse2;
                       document.getElementById("reponse1_1_3").innerHTML = doc.data().Reponse3;
                       document.getElementById("reponse1_1_4").innerHTML = doc.data().Reponse4;
                    } else {
                       // doc.data() will be undefined in this case
                       console.log("No such document!");
                    }
              }).catch(function(error) {
                    console.log("Error getting document:", error);
              });



        } else {
           window.location.href="account-connexion.html";
        }
     });

下面是我得到正确答案的地方

var docRef = db.collection("ReponseJ").doc("ReponseJuste");
                  docRef.get().then(function(doc) {
                        if (doc.exists) {
                           console.log("Document data:", doc.data());
                           document.getElementById("question1_1").innerHTML = doc.data().Question; //Here I have the corrected answer
                           document.getElementById("reponse1_1_1").innerHTML = doc.data().Reponse1;
                           var lisetRep = doc.data().Reponse1;
                           document.getElementById("reponse1_1_2").innerHTML = doc.data().Reponse2;
                           document.getElementById("reponse1_1_3").innerHTML = doc.data().Reponse3;
                           document.getElementById("reponse1_1_4").innerHTML = doc.data().Reponse4;
                        } else {
                           // doc.data() will be undefined in this case
                           console.log("No such document!");
                        }
                  }).catch(function(error) {
                        console.log("Error getting document:", error);
                  });

Answer 1

您需要chain the promises，并使在第一个then() 块中捕获的值在第二个then() 块中可用，如下所示。我使用了一个数组，但您可以使用任何其他等效方法。

      var answerArray = [];

      docRef
        .get()
        .then(function (doc) {
          if (doc.exists) {
            answerArray.push(doc.data().Reponse1);
            answerArray.push(doc.data().Reponse2);
            answerArray.push(doc.data().Reponse3);
            answerArray.push(doc.data().Reponse4);

            console.log('Document data:', doc.data());
            document.getElementById(
              'question1_1'
            ).innerHTML = doc.data().Question; //Here I have my user's answer
            document.getElementById(
              'reponse1_1_1'
            ).innerHTML = doc.data().Reponse1;
            var lisetRep = doc.data().Reponse1;
            document.getElementById(
              'reponse1_1_2'
            ).innerHTML = doc.data().Reponse2;
            document.getElementById(
              'reponse1_1_3'
            ).innerHTML = doc.data().Reponse3;
            document.getElementById(
              'reponse1_1_4'
            ).innerHTML = doc.data().Reponse4;

            // See the return below
            return db.collection("ReponseJ").doc("ReponseJuste").get(); 

          } else {
            // doc.data() will be undefined in this case
            console.log('No such document!');
            throw new Error('...');
          }
        })
        .then(function (doc) {
          if (doc.exists) {
              // Here compare the answers and the correct responses
              // For example
              if (answerArray[0] === doc.data().Reponse1 && answerArray[1] === doc.data().Reponse2 && ...) {

              }
          }
        }
        .catch(function (error) {
          console.log('Error getting document:', error);
        });
    } else {
      window.location.href = 'account-connexion.html';
    }
  });