Angular Material 2 DataTable Sorting with nested objects

I have a normal Angular Material 2 DataTable with sort headers. All sort are headers work fine. Except for the one with an object as value. These doesn't sort at all.

For example:

 <!-- Project Column - This should sort!-->
    <ng-container matColumnDef="project.name">
      <mat-header-cell *matHeaderCellDef mat-sort-header> Project Name </mat-header-cell>
      <mat-cell *matCellDef="let element"> {{element.project.name}} </mat-cell>
    </ng-container>

note the element.project.name

Here's the displayColumn config:

 displayedColumns = ['project.name', 'position', 'name', 'test', 'symbol'];

Changing 'project.name' to 'project' doesn't work nor "project['name']"

What am I missing? Is this even possible?

Here's a Stackblitz: Angular Material2 DataTable sort objects

Edit: Thanks for all your answers. I've already got it working with dynamic data. So I don't have to add a switch statement for every new nested property.

Here's my solution: (Creating a new DataSource which extends MatTableDataSource is not necessary)

export class NestedObjectsDataSource extends MatTableDataSource<MyObjectType> {

  sortingDataAccessor: ((data: WorkingHours, sortHeaderId: string) => string | number) =
    (data: WorkingHours, sortHeaderId: string): string | number => {
      let value = null;
      if (sortHeaderId.indexOf('.') !== -1) {
        const ids = sortHeaderId.split('.');
        value = data[ids[0]][ids[1]];
      } else {
        value = data[sortHeaderId];
      }
      return _isNumberValue(value) ? Number(value) : value;
    }

  constructor() {
    super();
  }
}

It was hard to find documentation on this, but it is possible by using sortingDataAccessor and a switch statement. For example:

@ViewChild(MatSort) sort: MatSort;

ngOnInit() {
  this.dataSource = new MatTableDataSource(yourData);
  this.dataSource.sortingDataAccessor = (item, property) => {
    switch(property) {
      case 'project.name': return item.project.name;
      default: return item[property];
    }
  };
  this.dataSource.sort = sort;
}

You can write a function in component to get deeply property from object. Then use it in dataSource.sortingDataAccessor like below

getProperty = (obj, path) => (
  path.split('.').reduce((o, p) => o && o[p], obj)
)

ngOnInit() {
  this.dataSource = new MatTableDataSource(yourData);
  this.dataSource.sortingDataAccessor = (obj, property) => this.getProperty(obj, property);
  this.dataSource.sort = sort;
}

columnDefs = [
  {name: 'project.name', title: 'Project Name'},
  {name: 'position', title: 'Position'},
  {name: 'name', title: 'Name'},
  {name: 'test', title: 'Test'},
  {name: 'symbol', title: 'Symbol'}
];

And in html

<ng-container *ngFor="let col of columnDefs" [matColumnDef]="col.name">
      <mat-header-cell *matHeaderCellDef>{{ col.title }}</mat-header-cell>
      <mat-cell *matCellDef="let row">
        {{ getProperty(row, col.name) }}
      </mat-cell>
  </ng-container>

The answer as given can even be shortened, no switch required, as long as you use the dot notation for the fields.

ngOnInit() {
  this.dataSource = new MatTableDataSource(yourData);

  this.dataSource.sortingDataAccessor = (item, property) => {
     if (property.includes('.')) return property.split('.').reduce((o,i)=>o[i], item)
     return item[property];
  };

  this.dataSource.sort = sort;
}

I use a generic method which allows you to use a dot.seperated.path with mat-sort-header or matColumnDef. This fails silently returning undefined if it cannot find the property dictated by the path.

function pathDataAccessor(item: any, path: string): any {
  return path.split('.')
    .reduce((accumulator: any, key: string) => {
      return accumulator ? accumulator[key] : undefined;
    }, item);
}

You just need to set the data accessor

this.dataSource.sortingDataAccessor = pathDataAccessor;

I like @Hieu_Nguyen solutions. I'll just add that if you use lodash in you project as I do then the solution translates to this:

import * as _ from 'lodash';

this.dataSource.sortingDataAccessor = _.get; 

No need to reinvent the deep property access.

I customized for multiple nested object level.

this.dataSource.sortingDataAccessor =
  (data: any, sortHeaderId: string): string | number => {
    let value = null;
    if (sortHeaderId.includes('.')) {
      const ids = sortHeaderId.split('.');
      value = data;
      ids.forEach(function (x) {
        value = value? value[x]: null;
      });
    } else {
      value = data[sortHeaderId];
    }
    return _isNumberValue(value) ? Number(value) : value;
  };

Another alternative, that no one threw out here, flatten the column first...

yourData.map((d) => 
   d.flattenedName = d.project && d.project.name ? 
                     d.project.name : 
                     'Not Specified');

this.dataSource = new MatTableDataSource(yourData);

Just another alternative, pros and cons for each!

Just add this to your data source and you will be able to access the nested object

this.dataSource.sortingDataAccessor = (item, property) => {
	// Split '.' to allow accessing property of nested object
	if (property.includes('.')) {
		const accessor = property.split('.');
		let value: any = item;
		accessor.forEach((a) => {
			value = value[a];
		});
		return value;
	}
	// Access as normal
	return item[property];
};

If you want to have an Angular material table with some extended features, like sorting for nested objects have a look at https://github.com/mikelgo/ngx-mat-table-extensions/blob/master/libs/ngx-mat-table/README.md .

I created this lib because I was missing some features of mat-table out of the box.

The advanced sorting is similar to @Hieu Nguyen suggested answer but a bit extended to also have proper sorting by upper and smaller case letters.

It's trying to sort by element['project.name']. Obviously element doesn't have such a property.

It should be easy to create a custom datasource that extends MatTableDatasource and supports sorting by nested object properties. Check out the examples in material.angular.io docs on using a custom source.

I had the same issue, by testing the first proposition I had some errors, I could fixe it by adding "switch (property)"

this.dataSource.sortingDataAccessor =(item, property) => {
    switch (property) {
    case 'project.name': return item.project.name;
           
    default: return item[property];
    }
  };

Use MatTableDataSource Check complete MatSort issue solution

in HTML

    <ng-container matColumnDef="createdDate" @bounceInLeft>
      <th mat-header-cell *matHeaderCellDef mat-sort-header class="date"> Created date
      </th>
          <td mat-cell *matCellDef="let element" class="date"> {{element.createdDate
           | date :'mediumDate'}} </td>
   </ng-container>

  <ng-container matColumnDef="group.name">
    <th mat-header-cell *matHeaderCellDef mat-sort-header class="type"> Group </th>
    <td mat-cell *matCellDef="let element" class="type"> {{element.group.name}} </td>
  </ng-container>

@ViewChild(MatSort, { static: true }) sort: MatSort;

    ngOnInit() {
      this.dataSource = new MatTableDataSource(yourData);
      this.dataSource.sortingDataAccessor = (item, property) => {
    switch(property) {
      case 'project.name': return item.project.name;
      default: return item[property];
    }
  };
  this.dataSource.sort = sort;
}

My table columns were not ordering correctly, so I modified one of the answers to work with my data.

function pathDataAccessor(item: any, path: string): any {
  return (item: any, path: string): any => {
    return path.split(".").reduce((accumulator: any, key: string) => {
      let returnValue;
      if (accumulator) {
        returnValue = accumulator[key];
      } else {
        returnValue = undefined;
      }
      if (typeof returnValue === "string") {
        returnValue = returnValue.trim().toLocaleLowerCase();
      }
      return returnValue;
    }, item);
  };
}