Fixed #981

src/app/components/datatable/datatable.ts

@@ -572,6 +572,8 @@ export class DataTable implements AfterViewChecked,AfterViewInit,AfterContentIni
     @Input() metaKeySelection: boolean = true;
 
     @Input() rowTrackBy: Function = (index: number, item: any) => item;
+
+    @Input() compareSelectionBy: string = 'deepEquals';
 
     @Output() onEditInit: EventEmitter<any> = new EventEmitter();
 
@@ -1301,7 +1303,7 @@ export class DataTable implements AfterViewChecked,AfterViewInit,AfterContentIni
         let index: number = -1;
         if(this.selection) {
             for(let i = 0; i  < this.selection.length; i++) {
-                if(this.objectUtils.equals(rowData, this.selection[i], this.dataKey)) {
+                if(this.equals(rowData, this.selection)) {
                     index = i;
                     break;
                 }
@@ -1312,7 +1314,18 @@ export class DataTable implements AfterViewChecked,AfterViewInit,AfterContentIni
     }
 
     isSelected(rowData) {
-        return ((rowData && this.objectUtils.equals(rowData, this.selection, this.dataKey)) || this.findIndexInSelection(rowData) != -1);
+        if(rowData && this.selection) {
+            if(this.selection instanceof Array)
+                return this.findIndexInSelection(rowData) > -1;
+            else
+                return this.equals(rowData, this.selection);
+        }
+
+        return false;
+    }
+
+    equals(data1, data2) {
+        return this.compareSelectionBy === 'equals' ? (data1 === data2) : this.objectUtils.equals(data1, data2, this.dataKey);
     }
 
     get allSelected() {

src/app/showcase/components/datatable/datatabledemo.html

@@ -573,8 +573,10 @@ <h3>Filtering</h3>
             <h3>Selection</h3>
             <p>DataTable provides single and multiple selection modes on click of a row. Selected rows are bound to the selection property and onRowSelect-onRowUnselect events
             are provided as optional callbacks. Alternatively column based selection can be done using radio buttons or checkboxes using selectionMode of a particular column.
-            When comparing if a row is selected, DataTable traverses all properties of the object which affects performance as a result. It is suggested to define a dataKey property
-            that uniquely identifies a record to avoid deep object comparison and increase performance.</p>
+            When resolving if a row is selected, by default DataTable uses deepEquals which traverses all properties of the object thus affects performance as a result so it is suggested to define a dataKey property
+            that uniquely identifies a record to avoid deep object comparison and increase performance. Another alternative is to compare rows by reference using compareSelectionBy property as "equals". See compareSelectionBy
+            in properties section for more information. Depending on your case you may use "equals" and "deepEquals" alternatives.</p>
+
             <p>In single mode, selection binding is an object reference.</p>
 <pre>
 <code class="language-typescript" pCode ngNonBindable>
@@ -1275,6 +1277,12 @@ <h3>Properties</h3>
                             <td>null</td>
                             <td>Function to optimize the dom operations by delegating to ngForTrackBy, default algoritm checks for object identity.</td>
                         </tr>
+                        <tr>
+                            <td>compareSelectionBy</td>
+                            <td>string</td>
+                            <td>deepEquals</td>
+                            <td>Algorithm to define if a row is selected, valid values are "equals" that compares by reference and "deepEquals" that compares all fields.</td>
+                        </tr>
                     </tbody>
                 </table>
             </div>