如何从Firebase中的snapshot.val（）或snapshot.exportVal（）获取属性/值？ [英] How to get properties / values from snapshot.val() or snapshot.exportVal() in Firebase?

问题描述

我能够以 snapshot 的形式获取我感兴趣的对象，如此 CodePen

I was able to fetch my interested object as snapshot as shown in this CodePen

以下是代码段：

$scope.post = {};
        var postsRef = new Firebase('https://docs-examples.firebaseio.com/web/saving-data/fireblog/posts');

        $scope.searchPost = function () {
            console.log('searched for author : ' + $scope.post.authorName);

            postsRef.orderByChild('author')
                .equalTo($scope.post.authorName)
                .once('value', function (snapshot) {
                    var val = snapshot.val();
                    console.log("Searched Post is : ");
                    console.log(val);
                    console.log("(From Val) Title is : " + val.title);

                    var exportVal = snapshot.exportVal();
                    console.log("Export Value is : ");
                    console.log(exportVal);
                    console.log("(From Export Val) Title is : " + exportVal.title);
                });
        }

这是 Firebase数据集正在使用。

当我搜索作者时： gracehop ，我得到了正确的快照但是，我无法访问其中的 title 等属性。 val.title & exportVal.title 将 undefined 作为输出。

When I search for author: gracehop, I get the correct snapshot but, I'm not able to access properties like title inside that. Both val.title & exportVal.title are giving undefined as output.

如何从快照中获取感兴趣的属性？

How do I get the interested properties from snapshot?

推荐答案

查询返回包含匹配子项的快照，并且它是子项包含您感兴趣的属性。

The query returns a snapshot containing the matching children and it is the children that contain the properties in which you are interested.

您可以使用快照的 forEach 方法枚举子项：

You can enumerate the children using the snapshot's forEach method:

postsRef.orderByChild('author')
    .equalTo($scope.post.authorName)
    .once('value', function (snapshot) {

        snapshot.forEach(function (childSnapshot) {

            var value = childSnapshot.val();
            console.log("Title is : " + value.title);
        });
    });

这篇关于如何从Firebase中的snapshot.val（）或snapshot.exportVal（）获取属性/值？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！