How to Use Node App to Return a File for Direct Download in Browser?

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1

This topic was automatically generated from Slack. You can find the original thread here.

Using the Node app, how can I return a file to be downloaded directly in the browser?

2

To return a file to be downloaded directly in the browser, you can create an HTTP endpoint using Pipedream and read the file from the /tmp directory. Here’s an example of how to create an HTTP endpoint and return the contents of a file: import fs from "fs"; export default defineComponent({ async run({ steps, $ }) { const fileContent = (await fs.promises.readFile('/tmp/your-file')).toString(); $.res.setHeader("Content-Disposition", "attachment; filename=your-file"); $.res.setHeader("Content-Type", "application/octet-stream"); $.res.end(fileContent); } }); This code reads the file from the /tmp/your-file path and sets the appropriate headers to trigger a download in the browser. Replace your-file with the actual filename you want to serve. Please note that you’ll need to save the file to the /tmp directory beforehand. You can learn more about working with files in Pipedream at Working with the filesystem in Node.js.

3

I want to return a JSON file in the browser. I will define the JSON in the same step.

4

To return a JSON file in the browser using Pipedream, you can create an HTTP endpoint and set the appropriate headers. Here’s an example of how to create an HTTP endpoint and return a JSON object: export default defineComponent({ async run({ $ }) { const jsonObject = { key1: "value1", key2: "value2", }; $.res.setHeader("Content-Disposition", "attachment; filename=jsonFile.json"); $.res.setHeader("Content-Type", "application/json"); $.res.end(JSON.stringify(jsonObject)); }, }); This code defines a JSON object and sets the appropriate headers to trigger a download in the browser. The JSON object will be downloaded as a file named jsonFile.json.

5

Here’s my code:

export default defineComponent({
  async run({ steps, $ }) {

    
    const jsonObject = {
      key1: steps.trigger.event.query.facebookId,
      key2: steps.trigger.event.query.measurementId,
    };

    $.res.setHeader("Content-Disposition", "attachment; filename=ga4-facebook.json");
    $.res.setHeader("Content-Type", "application/json");
    $.res.end(JSON.stringify(jsonObject));
  },
});

It’s giving me an error:
TypeError
Cannot read properties of undefined (reading 'setHeader')

6

It looks like you’re trying to set headers and send a JSON response using the $.res object. However, the $.res object is not available in a regular Pipedream component. To achieve this, you should use an HTTP trigger as the first step of your workflow. Here’s an example of how to create an HTTP trigger and return a JSON object: 1. Add an HTTP trigger as the first step of your workflow. 2. Add a Node.js code step with the following code: export default defineComponent({ async run({ steps, $ }) { const jsonObject = { key1: steps.trigger.event.query.facebookId, key2: steps.trigger.event.query.measurementId, }; $.res.setHeader("Content-Disposition", "attachment; filename=ga4-facebook.json"); $.res.setHeader("Content-Type", "application/json"); $.res.end(JSON.stringify(jsonObject)); }, }); Now, when you make an HTTP request to the endpoint URL of the HTTP trigger, it will return the JSON object as a downloadable file named ga4-facebook.json.

7

the first step is an HTTP request trigger and then I have the Node step.

It still gives me this error when I send a GET request to the trigger.

TypeError
Cannot read properties of undefined (reading 'setHeader')
8

I apologize for the confusion earlier. If you’re using an HTTP trigger, you should use the $.res object in the trigger step instead of the Node.js code step. Here’s how you can modify your workflow: 1. Click on the settings icon (gear icon) on your HTTP trigger step. 2. Scroll down to the “Respond with Custom HTTP Response” section. 3. Toggle the “Respond with Custom HTTP Response” option to enable it. 4. Add the following code in the “Code” section: const jsonObject = { key1: event.query.facebookId, key2: event.query.measurementId, }; $.res.setHeader("Content-Disposition", "attachment; filename=ga4-facebook.json"); $.res.setHeader("Content-Type", "application/json"); $.res.end(JSON.stringify(jsonObject)); 5. Save the changes and test your workflow by sending a GET request to the trigger URL. This should now return the JSON object as a downloadable file named ga4-facebook.json when you send a GET request to the trigger URL.

9

This is much close to working, however, the file is not downloaded to my browser. The JSON is just being displayed.

export default defineComponent({
  async run({ steps, $ }) {
    const jsonObject = {
      key1: steps.trigger.event.query.facebookId,
      key2: steps.trigger.event.query.measurementId,
    };

    await $.respond({
      status: 200,
      headers: {
        "Content-Displosition": "attachment",
        "filename": "ga4-facebook.json",
        "content-type": "application/json"
      },
      "body": jsonObject
    });
  },
});
10

I apologize for the confusion earlier. It seems there’s a typo in the header name. Please change "Content-Displosition" to "Content-Disposition" and make sure to include the filename in the same header. Here’s the corrected code: export default defineComponent({ async run({ steps, $ }) { const jsonObject = { key1: steps.trigger.event.query.facebookId, key2: steps.trigger.event.query.measurementId, }; await $.respond({ status: 200, headers: { "Content-Disposition": "attachment; filename=ga4-facebook.json", "Content-Type": "application/json" }, body: JSON.stringify(jsonObject) }); }, }); Now, when you send a GET request to the trigger URL, it should return the JSON object as a downloadable file named ga4-facebook.json.