CODEWITHSUNDEEP
nestjshttpservice
Prasad Gavande
Prasad Gavande

Reputation: 249

How to download data into JSON file from URL in nestjs?

I am trying to download data into JSON file from URL in nestjs but I cannot figure out how to do it.

Below is my controller function with reference to this answer.

export class DataController {
constructor(private readonly httpService: HttpService) { }

@Get()
async download(@Res() res) {
    const writer = createWriteStream('user.json');

    const response = await this.httpService.axiosRef({
        url: 'https://api.github.com/users/prasadg',
        method: 'GET',
        responseType: 'stream',
        headers: {
            'Content-Type': 'application/json',
        }
    });

    response.data.pipe(writer); <--- Error here:  Property 'pipe' does not exist on type 'unknown'.

    return new Promise((resolve, reject) => {
        writer.on('finish', resolve);
        writer.on('error', reject);
    });
}

As I mentioned above it is showing error

error TS2339: Property 'pipe' does not exist on type 'unknown'

Expected result : I want to write json data into file (user.json) in my folder on server.

How do I solve this problem?

Upvotes: 0

Views: 2689

Answers (2)

Vitor Kevin
Vitor Kevin

Reputation: 815

This is just a types mistake, make sure the axios is in your project by this command:

npm i axios

Then just declare the type in your response variable

@Get()
    async download() {
        const writer = createWriteStream('user.json');
        // response variable has to be typed with AxiosResponse<T> 
        const response: AxiosResponse<any> = await this.httpService.axiosRef({
            url: 'https://api.github.com/users/prasadg',
            method: 'GET',
            responseType: 'stream',
        });

        response.data.pipe(writer);

        return new Promise((resolve, reject) => {
            writer.on('finish', resolve);
            writer.on('error', reject);
        });
    }

Upvotes: 1

Kyle Johnson
Kyle Johnson

Reputation: 120

This is untested and I'm not sure it works. But there are a few misunderstandings in your code I can hopefully clear up and put you in the right direction.

export class DataController {
constructor(private readonly httpService: HttpService) { }

@Get()
async download(@Res() res) {
    const writer = createWriteStream('user.json');

    // Here you await the result of the request
    // Meaning you wait here until all the data is recieved, which is then stored in response
    const response = await this.httpService.axiosRef({
        url: 'https://api.github.com/users/prasadg',
        method: 'GET',
        responseType: 'stream',
        headers: {
            'Content-Type': 'application/json',
        }
    });

    // Here you are trying to use a function called pipe on the property data on the response
    response.data.pipe(writer); <--- Error here:  Property 'pipe' does not exist on type 'unknown'.

    return new Promise((resolve, reject) => {
        writer.on('finish', resolve);
        writer.on('error', reject);
    });
}

I imagine you would rather be doing something like this for the data pipe

writer.pipe(response.data);

If you are using fs.createWriteStream it will probably look more like this

writer.write(response.data);

You probably will want to put the request into the stream, so the data can be streamed as it is recieved, rather than having to await it

export class DataController {
constructor(private readonly httpService: HttpService) { }

@Get()
async download(@Res() res) {
    const writer = createWriteStream('user.json');

    writer.pipe(this.httpService.axiosRef({
            url: 'https://api.github.com/users/prasadg',
            method: 'GET',
            responseType: 'stream',
            headers: {
                'Content-Type': 'application/json',
            }
        });
    );

    return new Promise((resolve, reject) => {
        writer.on('finish', resolve);
        writer.on('error', reject);
    });
}

Like I said, the code isn't tested so your gonna have to play with it, but hopefully it puts you in the right direction

Upvotes: 0

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