diff --git a/projects/poweredsoft/data/package.json b/projects/poweredsoft/data/package.json
index c832b77..0b3815a 100644
--- a/projects/poweredsoft/data/package.json
+++ b/projects/poweredsoft/data/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@poweredsoft/data",
-  "version": "0.0.23",
+  "version": "0.0.24",
   "peerDependencies": {
     "rxjs": "^6.5.3"
   }
diff --git a/src/app/app.component.ts b/src/app/app.component.ts
index e4dbfaf..23c53d1 100644
--- a/src/app/app.component.ts
+++ b/src/app/app.component.ts
@@ -1,108 +1,130 @@
 import { Component, OnInit, Pipe } from '@angular/core';
 import { IDataSource } from 'projects/poweredsoft/data/src/lib/IDataSource';
 import { IDataSourceNotifyMessage } from 'projects/poweredsoft/data/src/lib/IDataSourceNotifyMessage';
-import { DataSource, IDataSourceTransportOptions, IDataSourceQueryAdapterOptions, IQueryCriteria, IQueryExecutionResult, IQueryExecutionGroupResult, IDataSourceCommandAdapterOptions } from 'projects/poweredsoft/data/src/public-api';
+import { DataSource, IDataSourceTransportOptions, IDataSourceQueryAdapterOptions, IQueryCriteria, IQueryExecutionResult, IQueryExecutionGroupResult, IDataSourceCommandAdapterOptions, IDataSourceValidationError } from 'projects/poweredsoft/data/src/public-api';
 import { HttpClient } from '@angular/common/http';
-import { of } from 'rxjs';
+import { of, throwError } from 'rxjs';
 
 export interface MyModel {
-  id: number;
-  name: string;
+    id: number;
+    name: string;
 }
 
 @Component({
-  selector: 'app-root',
-  templateUrl: './app.component.html',
-  styleUrls: ['./app.component.css']
+    selector: 'app-root',
+    templateUrl: './app.component.html',
+    styleUrls: ['./app.component.css']
 })
 
 export class AppComponent implements OnInit {
-  title = 'data';
-  message: string = '';
-  type: string = '';
+    title = 'data';
+    message: string = '';
+    type: string = '';
 
-  dataSource: IDataSource<any>;
-  createCommand: IDataSourceCommandAdapterOptions<MyModel>;
-  
-  public constructor(private http: HttpClient) {
+    dataSource: IDataSource<any>;
+    createCommand: IDataSourceCommandAdapterOptions<MyModel>;
 
-  }
+    public constructor(private http: HttpClient) {
 
-  ngOnInit(): void {
-    const keyResolver = (m: MyModel) => m.id;
-    let route = 'http://localhost:9999';
+    }
 
-    const query: IDataSourceQueryAdapterOptions<MyModel> = {
-      adapter: {
-          handle: (criteria: IQueryCriteria) => {
-              const queryRoute = `${route}/read`;
-              return this.http.post<IQueryExecutionResult<MyModel> & IQueryExecutionGroupResult<MyModel>>(queryRoute, criteria);
-          }
-      }
-  };
+    ngOnInit(): void {
+        const keyResolver = (m: MyModel) => m.id;
+        let route = 'http://localhost:9999';
 
-  this.createCommand = {
-      adapter: {
-          handle: (command: MyModel) => {
-              return of(command);
-              //return this.http.post<MyModel>(route, command);
-          }
-      }
-  };
+        const query: IDataSourceQueryAdapterOptions<MyModel> = {
+            adapter: {
+                handle: (criteria: IQueryCriteria) => {
+                    const queryRoute = `${route}/read`;
+                    return this.http.post<IQueryExecutionResult<MyModel> & IQueryExecutionGroupResult<MyModel>>(queryRoute, criteria);
+                }
+            }
+        };
 
-  const updateCommand: IDataSourceCommandAdapterOptions<MyModel> = {
-      adapter: {
-          handle: (command: MyModel) => {
-              const key = keyResolver(command);
-              const updateRoute = `${route}/${encodeURIComponent(key as any)}`;
-              return of(command);
-          }
-      }
-  };
+        this.createCommand = {
+            adapter: {
+                handle: (command: MyModel) => {
+                    return of(command);
+                    //return this.http.post<MyModel>(route, command);
+                }
+            }
+        };
 
-  const deleteCommand: IDataSourceCommandAdapterOptions<MyModel> = {
-      adapter: {
-          handle: (command: MyModel) => {
-              const key = keyResolver(command);
-              const updateRoute = `${route}/${encodeURIComponent(key as any)}`;
-              return of(command);
-          }
-      }
-  };
+        const updateCommand: IDataSourceCommandAdapterOptions<MyModel> = {
+            adapter: {
+                handle: (command: MyModel) => {
+                    const key = keyResolver(command);
+                    const updateRoute = `${route}/${encodeURIComponent(key as any)}`;
+                    return throwError(<IDataSourceValidationError>{
+                        type: 'validation',
+                        errors: {
+                            'name': [
+                                'David is not unique'
+                            ]
+                        }
+                    });
+                }
+            }
+        };
 
-  const transportOptions : IDataSourceTransportOptions<MyModel> = {
-      query: query,
-      commands: {
-          'create': this.createCommand,
-          'update': updateCommand,
-          'delete': deleteCommand
-      }
-  };
-    this.dataSource = new DataSource<MyModel>({
-      manageNotificationMessage: false,
-      transport: transportOptions,
-      defaultCriteria: {
-        page: 1,
-        pageSize: 5,
-        groups: [
-          { path: 'name' }
-        ]
-      }
-    });
+        const deleteCommand: IDataSourceCommandAdapterOptions<MyModel> = {
+            adapter: {
+                handle: (command: MyModel) => {
+                    const key = keyResolver(command);
+                    const updateRoute = `${route}/${encodeURIComponent(key as any)}`;
+                    return of(command);
+                }
+            }
+        };
 
-    this.dataSource.notifyMessage$.subscribe((notifyMessage: IDataSourceNotifyMessage) => {
-      this.handleNotification(notifyMessage);
-    });
-  }
+        const transportOptions: IDataSourceTransportOptions<MyModel> = {
+            query: query,
+            commands: {
+                'create': this.createCommand,
+                'update': updateCommand,
+                'delete': deleteCommand
+            }
+        };
+        this.dataSource = new DataSource<MyModel>({
+            manageNotificationMessage: false,
+            transport: transportOptions,
+            defaultCriteria: {
+                page: 1,
+                pageSize: 5,
+                groups: [
+                    { path: 'name' }
+                ]
+            }
+        });
 
-  handleNotification(notification: IDataSourceNotifyMessage) {
-    this.message = notification.message;
-  }
+        this.dataSource.notifyMessage$.subscribe((notifyMessage) => {
+            this.handleNotification(notifyMessage);
+        });
 
-  onDoSomething() {
-    this.dataSource.executeCommandByName('create', this.createCommand).subscribe(() => {
-      console.log('hey we did it!');
-    });
-    //this.dataSource.refresh();
-  }
+        this.dataSource.validationError$.subscribe((t) => {
+
+            let message = '';
+            for (var key in t.errors)
+                t.errors[key].forEach(error => message += `\n${error}`);
+
+            this.handleNotification({
+                type: 'error',
+                message: message
+            });
+        });
+    }
+
+    handleNotification(notification: IDataSourceNotifyMessage) {
+        this.message = notification.message;
+    }
+
+    onDoSomething() {
+        this.dataSource.executeCommandByName('create', {}).subscribe(() => {
+            console.log('hey we did it!');
+        });
+        this.dataSource.executeCommandByName('update', {}).subscribe(() => {
+
+        });
+        //this.dataSource.refresh();
+    }
 }