Arithmetic expressions must use numeric arguments

Question

The following class will get the content(a maximum of 10 MB) in encode format and I convert the content into decode format based on the my requirement into three parts. Now I want to add the all three blobs into single Blob to insert this content into attachment.

But while I am trying to add all three blobs into single blob, It is showing following error.

Even I gone through answer. But result comes without success.

Arithmetic expressions must use numeric arguments

Here is the class:

@RestResource(urlMapping='/stringoncase/*')
        global with sharing class RESTCaseController {
        @HttpPost
        global static String createNewCase(String Casenumber,String filename,String content1,String content2,String content3) {
                Case ca = [Select id,status,Origin from case where casenumber=:Casenumber];
            //ca.Status = status;
            //ca.Origin = web;
            //insert ca;

            blob base1 = EncodingUtil.base64Decode(content1);
            blob base2 = EncodingUtil.base64Decode(content2);
            blob base3 = EncodingUtil.base64Decode(content3);

            Attachment attachment = new Attachment();
            attachment.Body = Blob.valueOf(base1.toString() + base2.toString() + base3.toString());
            attachment.Name = filename;
            attachment.ParentId = ca.id;
            attachment.ContentType='multipart/form-data';//'application/json';
            insert attachment;

            return 'sucess';
        }
    }

I provide the input to the class using postman like the following

{

        "Casenumber" :"00001060",
        "filename" : "5_MBfiel.pdf",
        "content1" : "------Encoded data------",
        "content2" : "",
        "content3" : ""

}

How could I add these three blobs into single Blob?

Answer 1

Assuming that you have in content1, content2, content3 Base64 representations of text (not binary content), and assuming you just want to generate an attachment with the concatenation of those 3 strings, you could do the following

public class CaseController {
    global static String createNewCase(String Casenumber,String filename,String content1,String content2,String content3) {
        Case ca = [Select id,status,Origin from case where casenumber=:Casenumber];

        blob base1 = EncodingUtil.base64Decode(content1);
        blob base2 = EncodingUtil.base64Decode(content2);
        blob base3 = EncodingUtil.base64Decode(content3);

        Attachment attachment = new Attachment();
        attachment.Body = Blob.valueOf(base1.toString() + base2.toString() + base3.toString());
        attachment.Name = filename;
        attachment.ParentId = ca.id;
        insert attachment;
    }
}

Assuming that content1, content2 and content3 are 3 chunks of the SAME valid file, but in Base64 format, you could do...

public class CaseController {
    global static String createNewCase(String Casenumber,String filename,String content1,String content2,String content3) {
        Case ca = [Select id,status,Origin from case where casenumber=:Casenumber];

        blob base123 = EncodingUtil.base64Decode(content1 + content2 + content3);

        Attachment attachment = new Attachment();
        attachment.Body = base123;
        attachment.Name = filename;
        attachment.ParentId = ca.id;
        insert attachment;
    }
}