Angular CLI - Handle Error Globally

To handle error globally in Angular 7 Cli, follow below steps

Ref: https://angular.io/api/core/ErrorHandler

Steps:

- Create ErrorHanlder file as below

import { Injectable, ErrorHandler } from '@angular/core';

@Injectable()

export class GlobalErrorHandler implements ErrorHandler {

  constructor(private ngZone: NgZone) {

  }

  handleError(error) {

    this.ngZone.run(() => {

//use ngZone to attach context to Angular's zone

//custom logic to do anything, for ex: toastService can be injected and shown here

    });

    //log as error to console

    console.error(error);

  }

}

-  Inject GlobalErrorHandler into app.module.ts providers as below

import { NgModule, ErrorHandler } from '@angular/core';

import { GlobalErrorHandler } from './core/config/error.handler';

@NgModule({

  declarations: [

    AppComponent

  ],

  imports: [

  ],

  providers: [

    …,

    { provide: ErrorHandler, useClass: GlobalErrorHandler },

  ],

  bootstrap: [AppComponent]

})

export class AppModule { }

-  Now throw error from anywhere, it will be catched in GlobalErrorHanlder

import { catchError, map } from 'rxjs/operators';

import { Observable, of, throwError } from 'rxjs';

….

getUser(): Observable<User> {

      return this.http.get(this.getUserUrl      )

        .pipe(

        map(response => { return <User>response; }),

        catchError((error, caught) => {

          //handled error globally

          return throwError(error);

        }));

    }

C# - Pdf rotate using iTextSharp

In C#, with opensource iTextSharp can be find in nuget package, we can easily rotate each pdf pages and save as new file, use below code

using iTextSharp.text;

using iTextSharp.text.pdf;

using System.IO;

namespace PdfRotate

{

    class Program

    {

        static void Main(string[] args)

        {

            //INFO: Change input and ouput path here

            string pdfFilePath = @"C:\Files\sample.pdf";

            string outputPath = @" C:\Files\sampleoutput.pdf ";

            //INFO: Change rotate degree here to 90, 180 etc

            RotatePages(pdfFilePath, outputPath, 180);           

        }

        private static void RotatePages(string pdfFilePath, string outputPath, int rotateDegree)

        {

            PdfReader reader = new PdfReader(pdfFilePath);

            int pagesCount = reader.NumberOfPages;

            for (int n = 1; n <= pagesCount; n++)

            {

                PdfDictionary page = reader.GetPageN(n);

                PdfNumber rotate = page.GetAsNumber(PdfName.ROTATE);

                int rotation =

                        rotate == null ? rotateDegree : (rotate.IntValue + rotateDegree) % 360;

                page.Put(PdfName.ROTATE, new PdfNumber(rotation));

            }

            PdfStamper stamper = new PdfStamper(reader, new FileStream(outputPath, FileMode.Create));

            stamper.Close();

            reader.Close();

        }

    }

}