json/rest api:如何获取与特定值匹配的节点数 [英] json/rest api: how to get the count of nodes matching the specific value

问题描述

我在db.json中有数据(4000多个记录).我正在使用有角度的httpclient来显示数据(使用CRUD操作).

I have data in db.json (4000+ records). I am using angular httpclient to display the data (using CRUD operations).

其中一列是性别.现在，我想知道男性，女性和其他人的人数.

One of the columns is Gender. Now, I wanted to know the count of males, females, and others.

我需要在打字稿中写些什么才能知道所有记录中男性，女性以及其他人的数量和显示数量?

What do I need to write in my typescript to know the count and display number of males, females, and others out of all records?

app.component.html

app.component.html

{{impactCount.applicable}}  
{{impactCount.fyi}}

app.component.ts

app.component.ts

impactCount = {
    applicable: 0,
    fyi: 0
  }

     getLatestUser() {
    this.commonService.getAllUser().subscribe((response) => {
      this.allUser = response;
      this.totalRecords = this.allUser.length;
      this.allUser.forEach(row => this.impactCount[row.impact]++);
    })
  }

谢谢

推荐答案

您可以做一个简单的循环并添加另外两个名为 maleCount 和 femaleCount

You can do a simple loop and add two more variables called maleCount and femaleCount

genderCount = {
    male: 0;
    female: 0;
    other: 0;
}

getLatestUser() { 
    this.service.getAllUser().subscribe((response) => { 
        this.allUser = response; 
        this.totalRecords = this.allUser.length;

        this.allUser.forEach(row => {
            if (row.gender === 'Male') {
                this.genderCount.male++;
            } else if (row.gender === 'Female') {
                this.genderCount.female++;
            } else {
                this.genderCount.other++;
            }
        });
    }); 
}

或者，如果数据库中的性别选项将是"male"，"female"和"other"，则可以像这样访问它们并减少代码.

Alternatively, if the gender option in the db is going to be 'male', 'female', and 'other', you can access them like this and cut down on code.

this.allUser.forEach(row => this.genderCount[row.gender]++);

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