Convert Streaming PDF from String to viewable PDF

Question

I am trying to open a PDF that I am receiving as a streaming PDF from a microservice and open a visualforce page that contains the viewable PDF file. I can convert the streaming PDF to base64 using EncodingUtil.base64Encode. But am having troubles viewing the PDF from the visual force page.

Edit: Apex Class

@AuraEnabled
public static String getBase(){

    String pdfContent =  TenDashboardscallsController.HousehldQprReportPDF();
    Blob beforeBlob = blob.valueOf(pdfContent);
    String myBlob = EncodingUtil.base64Encode(beforeBlob);
    return myBlob;

}

PDF Response

Link to Original Response from TenDashboardscallsController.HousehldQprReportPDF() that is in the Apex class above https://justpaste.it/5zw0r

Answer 1

So I put together a sample VF page and controller that seems to work:

VF Page:
<apex:page controller="pdfController">
    <object data="{!'data:application/pdf;base64,'+pdfBase64}" type="application/pdf"></object>
</apex:page>

Controller:

public class pdfController
{
    public String pdfBase64 { get; private set; }

    public pdfController()
    {
        Http h = new Http();

        HttpRequest req = new HttpRequest();

        req.setMethod('GET');
        req.setEndpoint('http://www.africau.edu/images/default/sample.pdf');

        HttpResponse res = h.send(req);

        pdfBase64 = EncodingUtil.base64Encode(res.getBodyAsBlob());
    }
}

Answer 2

Adding for others to understand how to identify the correct format of the response received from the api. Specifically when you expect a pdf file from the api. If not done correctly you will se blank pdf pages.

https://developer.salesforce.com/forums/?id=9062I000000IUKAQA4

pasting my answer below incase link breaks

HttpResponse response = h.send(req);

Its important to understand why blob.valueof(response.getBody()) did not work and response.getbodyasblob() works.

When using this

blob.valueof(response.getBody()) response.getBody() is getting the body from the response in String format. the PDF file gets corrupted here itself. We the use blob.valueof() to convert the String to Blob for saving as contentversion.attachment.

response.getbodyasblob() this methods retrieves the body from response directly as Blob. So no conversion takes place and pdf file is intact.

Why EncodingUtil.Base64Decode(response.getBody()) does not work here is because the response from the API is not a Base64 string. If you actually check the response you will find strange characters. Base64 only supports these characters:

Uppercase letters (indices 0-25): ABCDEFGHIJKLMNOPQRSTUVWXYZ Lowercase letters (indices 26-51): abcdefghijklmnopqrstuvwxyz Digits (indices 52-61): 0123456789 Special symbols (indices 62-63): +/

So trying to using EncodingUtil.Base64Decode(response.getBody()) with our response will give error of invalid characters. If you dig deeper and check the response received using System.debug(response.getBody()) you will realize that it is actually a PDF file format (the PDF specification for creating pdf files here (https://resources.infosecinstitute.com/topic/pdf-file-format-basic-structure/)). So we do not have to decode or uncompress the response in any way. We have to just retrieve the file as it is (as a blob) and save it to salesforce.

Example of (response.getBody()) you will see for these api responses which return PDF files.

%PDF-1.4 %���� 2 0 obj <</ColorSpace/DeviceRGB/Subtype/Image/Height 200/Filter/FlateDecode/Type/XObject/DecodeParms<</Columns 420/Colors 3/Predictor 15/BitsPerComponent 8>>/Width 420/Length 6827/BitsPerComponent 8>>stream x�� |���gfw�MBr�r�p1Ax)X�QZ,�*Z����h��`�XĖ��Z���)��A���A�=f�'�� �3��N�e��}?���d���;��3�� �����Bv� ;����