I am trying to download a file with typescript (Node.js) using node-fetch.
As per the documentation and a stack overflow answer here the following code should work:
public async downloadXMLFeed(): Promise<void>{
// function for download the file to
// a temporary location
let fileStream = fs.createWriteStream(FILE_PATH, {encoding: "utf-8"});
fetch(FILE_URL)
.then((response) => {
response.body.pipe(fileStream)
fileStream.on("finish", () => {
fileStream.close();
})
});
but I get the following error:
Property 'pipe' does not exist on type 'Response'
I also checked the type file for response in node-fetch types. It does not have a pipe function.
I checked the type definition for node-fetch here and it seems the body in response is a readable stream as per the interface here:
export class Body {
constructor(body?: any, opts?: { size?: number; timeout?: number });
arrayBuffer(): Promise<ArrayBuffer>;
blob(): Promise<Buffer>;
body: NodeJS.ReadableStream; // This should work.
bodyUsed: boolean;
buffer(): Promise<Buffer>;
json(): Promise<any>;
size: number;
text(): Promise<string>;
textConverted(): Promise<string>;
timeout: number;
}
and has a function pipeTo (I found this from the documentationhere . I tried run the following code after going through the mentioned documentation:
public async downloadXMLFeed(): Promise<void>{
// function for download the file to
// a temporary location
let fileStream = fs.createWriteStream(FILE_PATH, {encoding: "utf-8"});
fetch(FILE_URL)
.then((response) => {
response.body.pipe(fileStream)
fileStream.on("finish", () => {
fileStream.close();
})
});
However I get the error:
Argument of type 'WriteStream' is not assignable to parameter of type 'WritableStream<Uint8Array>'.
Type 'WriteStream' is missing the following properties from type 'WritableStream': locked, abort, getWriter
Now the following code:
fs.createWriteStream(FILE_PATH, {encoding: "utf-8"});
returns an object with type WriteStream (checked here ) which implements stream.Writable. So I don't understands why doesn't the WriteStream object have the mentioned functions.
Also, how do I solve this? Is there a standard way of downloading http files in typescript with a node.js backend that I am not being able to figure out? Or am I missing something here.
but I get the following error:
Property 'pipe' does not exist on type 'Response'
This error is also triggered by this code
async function download() {
const res = await fetch('https://assets-cdn.github.com/images/modules/logos_page/Octocat.png');
await new Promise((resolve, reject) => {
const fileStream = fs.createWriteStream('./octocat.png');
res.body.pipe(fileStream);
res!.body!.on("error", (err) => {
reject(err);
});
fileStream.on("finish", function() {
resolve();
});
});
}
taken from here . The error is triggered because the fetch
function is interpreted as JS fetch .
To fix the error add import nodeFetch from "node-fetch";
and replace fetch(...)
with nodeFetch(...)
.
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