Populate length of array of array in angular table

Question

Basically, I have this data

{
   [
      {
         "name":"aiman",
         "subject":[
            {
               "name_subject":"Malay_language",
               "code":123
            },
            {
               "name_subject":"English_language",
               "code":1234
            }
         ]
      },
      {
         "name":"wani",
         "subject":[
            {
               "name_subject":"Malay_language",
               "code":123
            }
         ]
      }
   ]
}

Basically what should I do in order getting this?

student name	number of subject
Aiman	2
Wani	1

I have tried this, but it does not work..

 <tr *ngFor="let student of students">
                
                <td>{{student.name}}</td>
                <td>{{student.subject.length}}</td>
               
              
</tr>

chris burd · Accepted Answer · 2021-07-18 13:11:23Z

1

You can do this in a variance of ways through the html you can add an index and a counter

<tr *ngFor="let student of students; let i=index">
    <td *ngIf="student.subject===math">{{I+1}}</td>
    <td>{{ student.name }}</td>
    <td>{{ student.subject.length }}</td>
</tr>

or in the component you can use forEach and count it

studentMath?: number;
studentDAta.forEach((student)=>{
if(student.class===math){
this.studentMath= ++;
})

or you reduce the value of the array and count it

studentData
        .reduce(function(prev, curr){
            return (curr.studentMath) ? prev.concat(curr.studentMath) : prev;
        }, [])
        .map(function(q){ 
            return (q.value)? q.value : 0;
        })
        .reduce(function(prev, curr){
            return prev + curr;
        }, 0);
    }

answered Jul 18, 2021 at 13:11

chris burd

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