将FirestoreCollection转换为数组? [英] Convert FirestoreCollection into an array?
问题描述
我很难将Firestore数据转换为chart.js图的数组.
I'm having difficulty converting the Firestore data into an array for the chart.js graph.
从Firestore获取数据
fetchData(){
//Get data
this.updatesCollection = this.afs.collection(pathStats);
this.updates = this.updatesCollection.valueChanges();
}
创建图表
createChart(){
this.chart = new Chart('canvas', {
type: 'line',
data: {
labels: ['5/18/18', '5/19/18', '5/20/18', '5/21/18', '5/22/18', '5/23/18'],
datasets: [{
label: 'Filled',
backgroundColor: 'gray',
data: [4, 3, 5, 2, 6, 7],
fill: true,
}]
},
}
)
我现在正在使用硬编码的值[4, 3, 5, 2, 6, 7]
作为我的数据点的占位符.我将如何使用Firestore的值呢?
I'm using the hard-coded values [4, 3, 5, 2, 6, 7]
right now as a placeholder for my data points. How would I use the values coming from Firestore instead?
解决方案
如以下Ohad所述:
let chartData;
this.updatesCollection.ref.get().then((querySnapshot) => {
chartData = querySnapshot.docs.map(doc => doc.data());
}
这将为您提供一个数组,每个文档都在其自己的索引中.您可以像访问其他任何对象(例如chartData[0].wheelCount
)一样访问各个属性.
This gets you an array with each document in it's own index. You can access individual properties like any other object (ie chartData[0].wheelCount
).
推荐答案
调用this.updatesCollection.get()
将异步返回querySnapshot
对象.
Calling this.updatesCollection.get()
will asynchronously return a querySnapshot
object.
querySnapshot
具有docs
属性,该属性是包含零个或多个documentSnapshot
对象的数组.可以使用.data()
方法提取这些数据.
A querySnapshot
has a docs
property which is an array containing zero or more documentSnapshot
objects. The data in these can be extracted with the .data()
method.
用于生成数组的代码如下所示:
The code for producing your array could look like this:
let chartData = this.updates.collection.get()
.then(querySnapshot => {
chartData = querySnapshot.docs.map(doc => doc.data())
})
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