sounds about right

projects/poweredsoft/data/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@poweredsoft/data",
-  "version": "0.0.22",
+  "version": "0.0.23",
   "peerDependencies": {
     "rxjs": "^6.5.3"
   }

projects/poweredsoft/data/src/lib/DataSource.ts

@@ -1,8 +1,12 @@
-import { Observable, of, Observer, BehaviorSubject } from 'rxjs';
+import { Observable, of, Observer, BehaviorSubject, throwError, Subject } from 'rxjs';
 import { IDataSource } from './IDataSource';
 import { IQueryExecutionResult, IQueryExecutionGroupResult, IFilter, ISort, IAggregate, IGroup, IQueryCriteria } from './models';
-import { finalize } from 'rxjs/operators';
+import { finalize, catchError, map } from 'rxjs/operators';
 import { IDataSourceOptions, IResolveCommandModelEvent } from '../public-api';
+import { IDataSourceErrorMessage } from './IDataSourceErrorMessage';
+import { IDataSourceValidationError } from './IDataSourceValidationError';
+import { IDataSourceError } from './IDataSourceError';
+import { IDataSourceNotifyMessage } from './IDataSourceNotifyMessage';
 
 export class DataSource<TModel> implements IDataSource<TModel> 
 {
@@ -10,12 +14,14 @@ export class DataSource<TModel> implements IDataSource<TModel>
     
     protected _dataSubject: BehaviorSubject<IQueryExecutionResult<TModel> & IQueryExecutionGroupResult<TModel>> = new BehaviorSubject(null);
     protected _loadingSubject: BehaviorSubject<boolean> = new BehaviorSubject(false);
+    protected _validationSubject: Subject<IDataSourceValidationError> = new Subject();
+    protected _notifyMessageSubject: Subject<IDataSourceNotifyMessage> = new Subject();
 
     protected _data$: Observable<IQueryExecutionResult<TModel> & IQueryExecutionGroupResult<TModel>>;
     protected _loading$: Observable<boolean>;
-
-    // TODO: Validation error subject
-    // TODO: Message error subject
+    protected _validationError$: Observable<IDataSourceValidationError>;
+    protected _notifyMessage$: Observable<IDataSourceNotifyMessage>;
+    public manageNotificationMessage: boolean;
 
     protected _criteria: IQueryCriteria = {
         page: null,
@@ -27,23 +33,43 @@ export class DataSource<TModel> implements IDataSource<TModel>
     };
 
     get data$() {
+        if (!this._data$)
+            this._data$ = this._dataSubject.asObservable();
+
         return this._data$;
     }
 
     get loading$() {
+        if (!this._loading$)
+            this._loading$ = this._loadingSubject.asObservable();
+
         return this._loading$;
     }
 
+    get validationError$() {
+        if (!this._validationError$)
+            this._validationError$ = this._validationSubject.asObservable();
+
+        return this._validationError$;
+    }
+
+    get notifyMessage$() {
+        if (!this._notifyMessage$)
+            this._notifyMessage$ = this._notifyMessageSubject.asObservable();
+
+        return this._notifyMessage$;
+    }
+
     constructor(public options: IDataSourceOptions<TModel>) {
         this._initCriteria();
-        this._initSubjectObservables();
     }
 
     protected _initCriteria() {
-
         if (!this.options.defaultCriteria) 
             return;
 
+        this.manageNotificationMessage = (null == this.options.manageNotificationMessage || !this.options.manageNotificationMessage) ? false : true;
+
         const copy: IQueryCriteria = JSON.parse(JSON.stringify(this.options.defaultCriteria));
         this._criteria.page = copy.page || this._criteria.page;
         this._criteria.pageSize = copy.pageSize || this._criteria.pageSize;
@@ -53,11 +79,6 @@ export class DataSource<TModel> implements IDataSource<TModel>
         this._criteria.sorts = copy.sorts || this._criteria.sorts;
     }
 
-    protected _initSubjectObservables() {
-        this._loading$ = this._loadingSubject.asObservable();
-        this._data$ = this._dataSubject.asObservable();
-    }
-
     resolveIdField<TKeyType extends any>(model: TModel): TKeyType {
         
         if (this.options.idField)
@@ -68,12 +89,10 @@ export class DataSource<TModel> implements IDataSource<TModel>
 
         throw new Error("Must specify an id field or supply a method to resolve the id field.");
     }
-   
 
     resolveCommandModelByName<T extends any>(event: IResolveCommandModelEvent<TModel>) : Observable<T> {
-        
-        if (!this.options.transport.commands.hasOwnProperty(event.command))
-            return Observable.throw(`command with name ${event.command} not found`);
+        if (!this.options.transport.commands.hasOwnProperty(name))
+            return Observable.throw(`command with name ${name} not found`);
 
         const commandOptions = this.options.transport.commands[event.command];
         if (commandOptions.resolveCommandModel)
@@ -84,11 +103,33 @@ export class DataSource<TModel> implements IDataSource<TModel>
     }
 
     executeCommandByName<TCommand, TResult>(name: string, command: TCommand) : Observable<TResult> {
-    
         if (!this.options.transport.commands.hasOwnProperty(name))
             return Observable.throw(`command with name ${name} not found`);
 
-        return this.options.transport.commands[name].adapter.handle(command);
+        return this.options.transport.commands[name].adapter.handle(command).pipe(
+            map(t => {
+                let message = `{command} was executed successfully..`;
+                if (!this.manageNotificationMessage)
+                    message = message.replace('{command}', name);
+
+                this._notifyMessageSubject.next({
+                    type: 'success',
+                    message: message
+                });
+                return t;
+            }),
+            catchError((err: IDataSourceError) => {
+                if (err.type == 'message')
+                    this._notifyMessageSubject.next({
+                        type: 'error',
+                        message: (err as IDataSourceErrorMessage).message
+                    });
+                else if(err.type == 'validation')
+                    this._validationSubject.next(err as IDataSourceValidationError);
+
+                return throwError(err);
+            })
+        );
     }
 
     private _query() : Observable<IQueryExecutionResult<TModel> & IQueryExecutionGroupResult<TModel>> {
@@ -104,10 +145,20 @@ export class DataSource<TModel> implements IDataSource<TModel>
                 .subscribe(
                     result => {
                         this.data = result;
+                        o.next(result);
                         this._dataSubject.next(this.data);
-                        o.next(result)
+                        this._notifyMessageSubject.next({
+                            message: 'New data has been read succesfully..',
+                            type: 'info'
+                        });
                     },
-                    err => o.error(err)
+                    err => {
+                        o.error(err);
+                        this._notifyMessageSubject.next({
+                            message: 'Something unexpected as occured during the query',
+                            type: 'error'
+                        });
+                    }
                 );
         });
     }

projects/poweredsoft/data/src/lib/IDataSource.ts

@@ -1,6 +1,8 @@
 import { Observable } from "rxjs";
 import { ISort, IFilter, IGroup, IAggregate, IQueryExecutionResult, IQueryExecutionGroupResult, IQueryCriteria } from "./models";
 import { IResolveCommandModelEvent } from "./IResolveCommandModelEvent";
+import { IDataSourceValidationError } from './IDataSourceValidationError';
+import { IDataSourceNotifyMessage } from './IDataSourceNotifyMessage';
 
 export interface IDataSource<TModel>
 {
@@ -12,6 +14,8 @@ export interface IDataSource<TModel>
 
     data$: Observable<IQueryExecutionResult<TModel> & IQueryExecutionGroupResult<TModel>>;
     loading$: Observable<boolean>;
+    validationError$: Observable<IDataSourceValidationError>;
+    notifyMessage$: Observable<IDataSourceNotifyMessage>;
 
     data: IQueryExecutionResult<TModel> & IQueryExecutionGroupResult<TModel>;
 

projects/poweredsoft/data/src/lib/IDataSourceError.ts

@@ -0,0 +1,4 @@
+export interface IDataSourceError {
+    type: 'message' | 'validation';
+}
+

projects/poweredsoft/data/src/lib/IDataSourceErrorMessage.ts

@@ -0,0 +1,7 @@
+import { IDataSourceError } from './IDataSourceError';
+
+export interface IDataSourceErrorMessage extends IDataSourceError {
+    message: string;
+}
+
+

projects/poweredsoft/data/src/lib/IDataSourceNotifyMessage.ts

@@ -0,0 +1,4 @@
+export interface IDataSourceNotifyMessage {
+    type: 'warning' | 'info' | 'success' | 'error';
+    message: string;
+}

projects/poweredsoft/data/src/lib/IDataSourceOptions.ts

@@ -8,6 +8,7 @@ export interface IDataSourceOptions<TModel> {
     idField?: string;
     resolveIdField?: (model: TModel) => any;
     defaultCriteria: IQueryCriteria;
+    manageNotificationMessage?: boolean;
 }
 
 export interface IDataSourceTransportOptions<TModel> {

projects/poweredsoft/data/src/lib/IDataSourceValidationError.ts

@@ -0,0 +1,6 @@
+import { IDataSourceError } from './IDataSourceError';
+
+export interface IDataSourceValidationError extends IDataSourceError
+{
+    errors: { [field: string]: string[]; }
+}

projects/poweredsoft/data/src/public-api.ts

@@ -12,4 +12,8 @@ export * from './lib/IDataSourceQueryAdapterOptions';
 export * from './lib/IQueryAdapter';
 export * from './lib/IResolveCommandModelEvent';
 export * from './lib/IDataSourceCommandAdapterOptions';
+export * from './lib/IDataSourceValidationError';
+export * from './lib/IDataSourceError';
+export * from './lib/IDataSourceErrorMessage';
+export * from './lib/IDataSourceNotifyMessage';