The syntax used is incorrect
Thursday, January 17, 2019
SQL Error: ORA-00942 Table or view does not exist
If you are getting this error on truncate command , you need to check if you have the privilege to truncate.
Tuesday, August 7, 2018
OAuth
Hey Guys,
In this blog we will discuss about OAuth . OAuth is used for authentication .
Basic Authentication:
It needs user id and password.
The combination of user id and password is encrypted and added to the header .
The backend validates the authentication data in the headers and allow/block the request.
OAuth 2 :
1. Grant Type : Client Credentials
2 .access token url:
3. Client ID :
4. Client Secret :
5. Scope : api
In this blog we will discuss about OAuth . OAuth is used for authentication .
Basic Authentication:
It needs user id and password.
The combination of user id and password is encrypted and added to the header .
The backend validates the authentication data in the headers and allow/block the request.
OAuth 2 :
1. Grant Type : Client Credentials
2 .access token url:
3. Client ID :
4. Client Secret :
5. Scope : api
Friday, June 22, 2018
Error: Cannot find module '@angular-devkit/core'
Hi Guys, You might have faced this error "Error: Cannot find module '@angular-devkit/core'" while calling the command "ng serve". The full stack trace is as below .
module.js:487
throw err;
^
Error: Cannot find module '@angular-devkit/core'
at Function.Module._resolveFilename (module.js:485:15)
at Function.Module._load (module.js:437:25)
at Module.require (module.js:513:17)
at require (internal/module.js:11:18)
at Object.<anonymous> (F:\shahbaz\study\angular4\projects\my-fifth-app\test5\node_modules\@angular-devkit\schematics\src\tree\virtual.js:10:16)
at Module._compile (module.js:569:30)
at Object.Module._extensions..js (module.js:580:10)
at Module.load (module.js:503:32)
at tryModuleLoad (module.js:466:12)
at Function.Module._load (module.js:458:3)
To fix just change the following property in package.json
"@angular/cli": "1.6.0",
to
"@angular/cli": "^1.6.0",
Once done run npm update
This should solve the problem.
module.js:487
throw err;
^
Error: Cannot find module '@angular-devkit/core'
at Function.Module._resolveFilename (module.js:485:15)
at Function.Module._load (module.js:437:25)
at Module.require (module.js:513:17)
at require (internal/module.js:11:18)
at Object.<anonymous> (F:\shahbaz\study\angular4\projects\my-fifth-app\test5\node_modules\@angular-devkit\schematics\src\tree\virtual.js:10:16)
at Module._compile (module.js:569:30)
at Object.Module._extensions..js (module.js:580:10)
at Module.load (module.js:503:32)
at tryModuleLoad (module.js:466:12)
at Function.Module._load (module.js:458:3)
To fix just change the following property in package.json
"@angular/cli": "1.6.0",
to
"@angular/cli": "^1.6.0",
Once done run npm update
This should solve the problem.
The "@angular/compiler-cli" package was not properly installed.
Hi Guys,
You might have faced this error "The "@angular/compiler-cli" package was not properly installed. Error: Error: Cannot find module '@angular/compiler-cli'" while calling the command "ng serve".
The full stack trace is as below
The "@angular/compiler-cli" package was not properly installed. Error: Error: Cannot find module '@angular/compiler-cli'
Error: The "@angular/compiler-cli" package was not properly installed. Error: Error: Cannot find module '@angular/compiler-cli'
at Object.CompilerCliIsSupported (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\node_modules\@ngtools\webpack\src\ngtools_api.js:25:15)
at new AotPlugin (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\node_modules\@ngtools\webpack\src\plugin.js:29:23)
at _createAotPlugin (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\models\webpack-configs\typescript.js:92:16)
at Object.getNonAotConfig (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\models\webpack-configs\typescript.js:100:19)
at NgCliWebpackConfig.buildConfig (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\models\webpack-config.js:33:37)
at Class.run (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\tasks\serve.js:71:98)
at check_port_1.checkPort.then.port (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\commands\serve.js:123:26)
at <anonymous>
at process._tickCallback (internal/process/next_tick.js:169:7)
It can due to various reasons ,The "@angular/compiler-cli" package was not properly installed. Error: Error: Cannot find module '@angular/compiler-cli'
Error: The "@angular/compiler-cli" package was not properly installed. Error: Error: Cannot find module '@angular/compiler-cli'
at Object.CompilerCliIsSupported (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\node_modules\@ngtools\webpack\src\ngtools_api.js:25:15)
at new AotPlugin (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\node_modules\@ngtools\webpack\src\plugin.js:29:23)
at _createAotPlugin (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\models\webpack-configs\typescript.js:92:16)
at Object.getNonAotConfig (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\models\webpack-configs\typescript.js:100:19)
at NgCliWebpackConfig.buildConfig (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\models\webpack-config.js:33:37)
at Class.run (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\tasks\serve.js:71:98)
at check_port_1.checkPort.then.port (C:\Users\user\AppData\Roaming\npm\node_modules\@angular\cli\commands\serve.js:123:26)
at <anonymous>
at process._tickCallback (internal/process/next_tick.js:169:7)
1. Your node_modules folder is not having the required modules .
Check the node_modules folder and see if it has all the modules. If the modules are missing just do npm install
2. If the modules are available check the version of typescript , nodejs and angular cli.
3. If nothing works create a new project using ng new project-name and replace the src directory.
Friday, June 8, 2018
ERROR Error: Uncaught (in promise): Error: Cannot match any routes. URL Segment:
Hi Guys,
This blog is about issues I have faced while creating a route in Angular 5.
When I try to hit a url "http://localhost:4200/home", I faced the following error.
Error: Cannot match any routes. URL Segment: 'home'
at ApplyRedirects.noMatchError (router.js:1719)
at CatchSubscriber.eval [as selector] (router.js:1684)
at CatchSubscriber.error (catchError.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at LastSubscriber.Subscriber._error (Subscriber.js:131)
at ApplyRedirects.noMatchError (router.js:1719)
at CatchSubscriber.eval [as selector] (router.js:1684)
at CatchSubscriber.error (catchError.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at LastSubscriber.Subscriber._error (Subscriber.js:131)
at resolvePromise (zone.js:821)
at resolvePromise (zone.js:785)
at eval (zone.js:870)
at ZoneDelegate.invokeTask (zone.js:421)
at Object.onInvokeTask (core.js:4744)
at ZoneDelegate.invokeTask (zone.js:420)
at Zone.runTask (zone.js:188)
at drainMicroTaskQueue (zone.js:594)
This blog is about issues I have faced while creating a route in Angular 5.
When I try to hit a url "http://localhost:4200/home", I faced the following error.
Error: Cannot match any routes. URL Segment: 'home'
at ApplyRedirects.noMatchError (router.js:1719)
at CatchSubscriber.eval [as selector] (router.js:1684)
at CatchSubscriber.error (catchError.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at LastSubscriber.Subscriber._error (Subscriber.js:131)
at ApplyRedirects.noMatchError (router.js:1719)
at CatchSubscriber.eval [as selector] (router.js:1684)
at CatchSubscriber.error (catchError.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at MapSubscriber.Subscriber._error (Subscriber.js:131)
at MapSubscriber.Subscriber.error (Subscriber.js:105)
at LastSubscriber.Subscriber._error (Subscriber.js:131)
at resolvePromise (zone.js:821)
at resolvePromise (zone.js:785)
at eval (zone.js:870)
at ZoneDelegate.invokeTask (zone.js:421)
at Object.onInvokeTask (core.js:4744)
at ZoneDelegate.invokeTask (zone.js:420)
at Zone.runTask (zone.js:188)
at drainMicroTaskQueue (zone.js:594)
The fix is pretty simple .When I added the following line in app.module.ts file , it worked.
const appRoutes:Routes =[ | |
{path:'home',component: HomeComponent} | |
]; |
If you are facing the same error even after adding this piece of code then check if you have added a slash in the path {path :'\home' . Remove the slash if you have added it.
view the full source in Git
view the full source in Git
Saturday, May 26, 2018
has been blocked by CORS policy: No 'Access-Control-Allow-Origin'
Hi Guys,
This blog is about issues I have faced while fetching data from a REST Web Service.
When I try to get the data from the service I faced an error like ,
<div class="container">
<div class="row">
<div>
Question:
<select id="question" >
<option>Select</option>
<option *ngFor="let question of questions" ngValue="question">{{question.subjectDesc}}</option>
</select>
</div>
</div>
<div class="row">
<div>
<button class="btn btn-primary" (click)="onGet()">Get Server Response </button>
</div>
</div>
</div>
This blog is about issues I have faced while fetching data from a REST Web Service.
When I try to get the data from the service I faced an error like ,
Failed to load http://localhost:8090/org.myProject/question: Redirect from 'http://localhost:8090/org.myProject/question' to 'http://localhost:8090/org.myProject/question/' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:4200' is therefore not allowed access.
This is because the rest service does not provide the response for Http requests from a different domain .
The solution to this is add some extra the configuration in the Service to accept requests from a different domains.
Lets have a look at the code.
import { EventEmitter, Injectable } from '@angular/core';
import { Headers, Http ,Response} from '@angular/http';
import { HttpClientModule } from '@angular/common/http';
import { HttpModule } from '@angular/http';
import 'rxjs/Rx';
import { Observable } from 'rxjs/Observable';
@Injectable()
export class QuestionService{
constructor(private http:Http) {}
loadQuestions(){
return this.http.get('http://localhost:8090/org.myProject/question')
.map(
(response: Response) => {
const data = response.json();
return data;
}
)
.catch(
(error: Response) => {
return Observable.throw('Something went wrong');
}
);
}
}
import { Headers, Http ,Response} from '@angular/http';
import { HttpClientModule } from '@angular/common/http';
import { HttpModule } from '@angular/http';
import 'rxjs/Rx';
import { Observable } from 'rxjs/Observable';
@Injectable()
export class QuestionService{
constructor(private http:Http) {}
loadQuestions(){
return this.http.get('http://localhost:8090/org.myProject/question')
.map(
(response: Response) => {
const data = response.json();
return data;
}
)
.catch(
(error: Response) => {
return Observable.throw('Something went wrong');
}
);
}
}
That's the service,check out the controller .
import { Component, OnInit } from '@angular/core';
import { QuestionService } from './question.service';
@Component({
selector: 'app-question',
templateUrl: './question.component.html',
styleUrls: ['./question.component.css'],
providers:[QuestionService]
})
export class QuestionComponent {
constructor(private questionService:QuestionService) { }
onGet() {
this.questionService.loadQuestions().subscribe(
(questions: any[]) => {this.questions = questions;console.log(questions);},
(error) => console.log(error)
);
}
var questions;
}
import { QuestionService } from './question.service';
@Component({
selector: 'app-question',
templateUrl: './question.component.html',
styleUrls: ['./question.component.css'],
providers:[QuestionService]
})
export class QuestionComponent {
constructor(private questionService:QuestionService) { }
onGet() {
this.questionService.loadQuestions().subscribe(
(questions: any[]) => {this.questions = questions;console.log(questions);},
(error) => console.log(error)
);
}
var questions;
}
The component file is as below
<div class="container">
<div class="row">
<div>
Question:
<select id="question" >
<option>Select</option>
<option *ngFor="let question of questions" ngValue="question">{{question.subjectDesc}}</option>
</select>
</div>
</div>
<div class="row">
<div>
<button class="btn btn-primary" (click)="onGet()">Get Server Response </button>
</div>
</div>
</div>
The change actually has to be done on the server side code . I am using a Spring Web application at the back end . By default it does not respond other hosts. So , Lets add the following entries to web.xml .
<filter>
<filter-name>CORS</filter-name>
<filter-class>com.thetransactioncompany.cors.CORSFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>CORS</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter-name>CORS</filter-name>
<filter-class>com.thetransactioncompany.cors.CORSFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>CORS</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
Test once the service is deployed.
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