failed to see preview after slack image download

[rr-jino-jose]

Hello

hope you are all doing good.

Issue:
I have a bot where user uploads a png file and submits. I was able to download those png to my system using url_private_download key value but somehow I am not able to preview it.

I am using the following code to download it. I think its some issues with writing to stream and not sure how to handle it. I did check some old issues posted in this repo and tried few codes but nothing worked.

# typescript code
const downloadImage= (url:string ,filename:string)=>{

  const promise = new Promise((resolve,reject)=>{
      const config = {
          headers: { Authorization: `Bearer ${process.env.SLACK_BOT_TOKEN}` }
      };
      axios({
          method: "GET",
          url  : url,
          responseType: "stream",
          headers : config.headers
      }).then((result)=>{
          const writeStream = fs.createWriteStream(filename);
          result.data.on('data', (chunk: any) => {
              writeStream.write(chunk);
          });
          result.data.on('end', function () {
              writeStream.uncork();
              writeStream.close();
              writeStream.end();
              console.log("completely ending the pipe");
          });
          writeStream.on('finish', () => {
              resolve(filename);
          });
          // This is here incase any errors occur
          writeStream.on('error', function (err) {
              reject(err);
          });
      }).catch((err)=>{
          reject(err);
      });
  });
  return promise;
};

any help is appreciated for the same.

@slack/bolt version

"@slack/bolt": "^4.1.1",

App and Receiver Configuration

const app = new App({
  token: process.env.SLACK_BOT_TOKEN as string,
  appToken: process.env.SLACK_APP_TOKEN as string,
  socketMode: true,
  logLevel: LogLevel.ERROR,
});

app.command('/requests', async ({ command, ack }) => {
    try {
      // Acknowledge command request
      await ack();
      // Open a modal for ticket submission
      await app.client.views.open({
        trigger_id: command.trigger_id,
        view: createIssueModal(command.channel_id),
        });
    } catch (error) {
    console.error(error);
  }
});

Node.js runtime version

 node --version                                                                                                                                                   
v18.19.0

Expected result:

after download I can preview the image

[seratch]

Hi @rr-jino-jose, thanks for asking the question.

somehow I am not able to preview it

What do you mean by "failt to preview it"? Does it mean the downloaded file data is broken? Are you looking for a way to display the file content in a message or on a modal?

If the file your code downloads is not valid, my past comment at #1711 (comment) may be helpful. I don't think the operation could be that complicated.

[rr-jino-jose]

Hey @seratch. Thanks for the reply.

Yes the downloaded file data is broken. I did tried your code, it downloads the file but can't open it .. Initially I thought it might be due to some missing permissions but its not. (I gave all the permissions for file:* in Bot Token Scopes and User Token Scopes)

After writing it into a file, when I open it gives me the error (in screenshot). Also I tried via terminal:

wget --header="Authorization: Bearer ${SLACK_BOT_TOKEN}" "https://files.slack.com/files-pri/<org hash code>/download/screenshot_2025-01-10_at_10.21.51___am__3_.png"

it downloads but can't open it via any application. So have no idea what else I might be missing.