I have a problem that unfortunately I cannot resolve.
My API returns me a list of data like this:
[
{grade: "Grade A", id: 1, ifsGrade: "A1XX", ifsType: "01XX", points: 22, type: "Type_1"},
{grade: "Grade B", id: 2, ifsGrade: "B1XX", ifsType: "02XX", points: 15, type: "Type_1"},
{grade: "Grade C", id: 3, ifsGrade: "C1XX", ifsType: "03XX", points: 1, type: "Type_1"},
{grade: "Grade A", id: 4, ifsGrade: "A2XX", ifsType: "04XX", points: 23, type: "Type_2"},
{grade: "Grade B", id: 5, ifsGrade: "B2XX", ifsType: "05XX", points: 26, type: "Type_2"}
]
And I group my data by type like this:
Array.prototype.groupBy = function(k) {
return this.reduce((acc, item) => (acc[item[k]] = [...(acc[item[k]] || []), item], acc), {});
};
var TABLE_DATA = Object.values(API_DATA.groupBy("type"));
[
[
{grade: "Grade A", id: 1, ifsGrade: "A1XX", ifsType: "01XX", points: 22, type: "Type_1"},
{grade: "Grade B", id: 2, ifsGrade: "B1XX", ifsType: "02XX", points: 15, type: "Type_1"},
{grade: "Grade C", id: 3, ifsGrade: "C1XX", ifsType: "03XX", points: 1, type: "Type_1"}
],
[
{grade: "Grade A", id: 4, ifsGrade: "A2XX", ifsType: "04XX", points: 23, type: "Type_2"},
{grade: "Grade B", id: 5, ifsGrade: "B2XX", ifsType: "05XX", points: 26, type: "Type_2"}
]
]
I would like to be able to display the data in a Angular Material mat-table like this:
So I do have a list for my dataSource but the elements of this list are lists too. So I don't know how to display the items correctly.
So for the table columns you would need something dynamic like this, but I don't know how:
<ng-container matColumnDef="{{column}}" *ngFor="let column of definedColumns">
<th mat-header-cell *matHeaderCellDef> {{column}} </th>
<td mat-cell *matCellDef="let element"> {{element[column]}} </td>
</ng-container>
Stackblitz link here
Thanks for your help
You will need to iterate through your data and map the different values to your new object.
Here's a working stack example https://stackblitz.com/edit/datasource-mat-table-with-group-by-ay2rbh
And the relevant functions from the stackblitz
convertedData: ElementType[];
// creates "gradeX" from "Grade X"
convertGradeToGradeKey(grade: string): string{
return `grade${grade.split(" ")[1]}`;
}
// probably worth typing this "data" properly as well...
mapDataFromApi(data: any[]): void {
// using a map so we don't have to iterate the whole list to find type === "someType" every time
let mappedData = new Map<string, ElementType>();
data.forEach(val => {
// get the existing value from the map, or ceate a "new" one if its not there
let currentVal = mappedData.get(val.type) || {type: val.type, gradeA: undefined, gradeB: undefined, gradeC: undefined};
// get the "grade key" from the string value
const gradeKey = this.convertGradeToGradeKey(val.grade);
// get the new value, which will be the curent value + this row's "poiints"
const newGradeValue: number = (currentVal[gradeKey] || 0) + val.points;
// merge the current value object with the new property
currentVal = {...currentVal, [gradeKey]: newGradeValue };
// add upate the value in the set
mappedData.set(val.type, currentVal);
})
// create a normal array from that mapped data
this.convertedData = [...mappedData].map(([key, val]) => val);
}
Data initialization with grouping by type
:
ngOnInit() {
this.API_DATA = [
{grade: "Grade A", id: 1, ifsGrade: "A1XX", ifsType: "01XX", points: 22, type: "Type_1"},
{grade: "Grade B", id: 2, ifsGrade: "B1XX", ifsType: "02XX", points: 15, type: "Type_1"},
{grade: "Grade C", id: 3, ifsGrade: "C1XX", ifsType: "03XX", points: 1, type: "Type_1"},
{grade: "Grade A", id: 4, ifsGrade: "A2XX", ifsType: "04XX", points: 23, type: "Type_2"},
{grade: "Grade B", id: 5, ifsGrade: "B2XX", ifsType: "05XX", points: 16, type: "Type_2"}
];
const key = 'type'
const dataTable = Object.values(this.API_DATA.reduce((acc, item) => (acc[item[key]] = [...(acc[item[key]] || []), item], acc), {}));
this.dataSource = dataTable;
}
mat-table
Angular material with dynamic columns:
<table mat-table [dataSource]="dataSource" class="mat-elevation-z8">
<ng-container matColumnDef="{{column}}" *ngFor="let column of definedColumns; let index = index;">
<th mat-header-cell *matHeaderCellDef> {{column}} </th>
<td mat-cell *matCellDef="let elements">
<span *ngFor="let element of elements; let first = first;">
<span *ngIf="index == 0 && first">{{element.type}}</span>
<span *ngIf="element.grade == column">{{element.points}}</span>
</span>
</td>
</ng-container>
<ng-container matColumnDef="action">
<th mat-header-cell *matHeaderCellDef class="text-right">
<button mat-icon-button (click)="log('add')">
<mat-icon color="accent">add_circle_outline</mat-icon>
</button>
</th>
<td mat-cell *matCellDef="let gradingIndex" class="text-right">
<button mat-icon-button>
<mat-icon color="primary" (click)="log(gradingIndex)">edit</mat-icon>
</button>
<button mat-icon-button (click)="log(gradingIndex)">
<mat-icon color="warn">delete</mat-icon>
</button>
</td>
</ng-container>
<tr mat-header-row *matHeaderRowDef="displayedColumns"></tr>
<tr mat-row *matRowDef="let row; columns: displayedColumns;"></tr>
</table>
Result:
Stackblitz: here
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