In Dynamics Ax implementation very often we get requirement to upload data using csv files. Although  in Dynamics 365 for operations it can be easily done using data entities and data packages, in this blog we will see how can we use new FileUpload control and design classes to read, download files.
In  Dynamics 365 for operations  application runs on cloud and the client is in web , so Microsoft has introduce new process to read files using Azure blob. When we upload file, that file gets uploaded to Azure blob and we have to read that file from Azure blob to retrieve data.

Design classes:

There are two main types of classes that developers can work with for the file upload control:
  • Upload strategy class – This class lets developers control various parameters that should be enforced for uploaded files, such as the types of files that a user can upload and the maximum size of a file. It also lets developers determine where and how the uploaded file should be stored.All upload strategy classes must inherit from the abstract FileUploadStrategyBaseclass. The framework provides a default upload strategy class named FileUploadTemporaryStorageStrategy
  • Upload result class – This class lets developers access the details of a file that was uploaded by a user, such as its name, content type, and upload status. It also lets developers open and delete the corresponding file. All upload result classes must inherit from the abstract FileUploadResultBase class. Default upload result class that is named FileUploadTemporaryStorageResult. This upload result class stores uploaded files to the temporary blob storage and provides a download URL.
Below is X++ code to create dialog which uploads file in to blob storage and get temporary URL  to retrieve data from the file.
public Object dialog()
    {
        DialogGroup      dialogGroup;
        FormBuildControl formBuildControl;
        FileUploadBuild  dialogFileUpload;
        Set              enumSet = new Set(Types::Enum);
               
        ;
       
        dialog = super();                 
        dialogGroup = dialog.addGroup(\”File path\”);
        formBuildControl = dialog.formBuildDesign().control(dialogGroup.name());
       
        dialogFileUpload = formBuildControl.addControlEx(classstr(FileUpload), FileUploadName);
        dialogFileUpload.style(FileUploadStyle::MinimalWithFilename);
        dialogFileUpload.baseFileUploadStrategyClassName(classstr(FileUploadTemporaryStorageStrategy));
        dialogFileUpload.fileTypesAccepted(availableTypes);
        dialogFileUpload.fileNameLabel(\”@SYS308842\”);
   
        return dialog;
 }

You can see in the above code I used FileUploadBuild  control and provided base class FileUploadTemporaryStorageStrategy to method baseFileUploadStrategyClassName  which will be used to upload file to azure blob.
The FileTypesAccepted property of the file upload control lets you limit the types of files that users can upload
dialogFileUpload.fileTypesAccepted(availableTypes);
availableTypes is private Variable declared in classdeclaratoin 
private str                 availableTypes = \”.csv\”;

In the class Declaration control names for OK and upload control
private const str OkButtonName = \’OkButton\’;
private const strFileUploadName = \’FileUpload\’;

Following methods is  required to Enables or disables the dialog Ok button.
protected voidsetDialogOkButtonEnabled(DialogRunbase _dialog, boolean _isEnabled)
{
        FormControl okButtonControl = this.getFormControl(_dialog, OkButtonName);
        if (okButtonControl)
        {
            okButtonControl.enabled(_isEnabled);
        }
}
protected FormControl getFormControl(DialogRunbase _dialog, str _controlName)
{
        return_dialog.formRun().control(_dialog.formRun().controlId( _controlName));
}
Once the file has been uploaded to blob storage ok button needs to be enabled. Following method takes care of that by calling callback event handler to be notified when upload is complete.
protected void uploadCompleted()
 {
        FileUpload fileUpload = this.getFormControl(dialog, FileUploadName);
        fileUpload.notifyUploadCompleted -= eventhandler(this.UploadCompleted);
               
        textFile = fileUpload.fileName();
        this.setDialogOkButtonEnabled(dialog, true);
    }
/// Disables the dialog Ok button until the file upload is complete.
   
    public void dialogPostRun(DialogRunbase _dialog)
    {
        FileUpload fileUpload = this.getFormControl(_dialog, FileUploadName);
        fileUpload.notifyUploadCompleted += eventhandler(this.uploadCompleted);
        this.setDialogOkButtonEnabled(_dialog, false);
    }
      Once dialog is open you can see file upload control where you can select file and Ok button is disabled.
     
Once file is uploaded to blob Ok button is enabled, you can see that in below screen.
Here is the code which reads the CSV file
void processCSVFile()
    {
        #File
        container               currentLine;
        int                     totalOfLines;
        CommaTextStreamIo       localStream;
        Num                     number;
           
      
        FileUpload fileUploadControl = this.getFormControl(dialog, FileUploadName);
       
        FileUploadTemporaryStorageResult fileUploadResult = fileUploadControl.getFileUploadResult();
       
        if (fileUploadResult != null && fileUploadResult.getUploadStatus())
        {
            textFile = fileUploadResult.getDownloadUrl();
        }
       
        localStream = CommaTextStreamIo::constructForRead(File::UseFileFromURL(textFile));
      
         
        if (localStream.status() != IO_Status::Ok)
        {
            throw error(strfmt(\’Is not possible to open the file. Error %1\’,enum2str(localStream.status())));
        }
   
        localStream.inFieldDelimiter(\”\\,\”);
        localStream.inRecordDelimiter(\”\\n\”);
   
        currentLine = localStream.read();
        fileLineNumber++;
   
        if(conlen(currentLine) == 1)
        {
            throw error(\’Is not possible to import the file, incorrect format\’);
        }
   
           
        currentLine = localStream.read();
        fileLineNumber++;
   
        while(currentLine)
        {
            number = conPeek(currentLine,1);
            info(strFmt(\”Number : %1\”,number));
            
            currentLine = localStream.read();
               
        }
   
    }
Here is my Sample CSV file to test the code
Infolog showing values of the number column from csv file.
If you have any feedback feel free to comment. Thanks for reading the blog and have a great day.
Reference:
https://docs.microsoft.com/en-us/dynamics365/unified-operations/dev-itpro/user-interface/file-upload-control