Support for Typescript docs

[SadmanYasar]

Question

I have been trying to implement server side sentiment analysis using this tutorial but its in Javascript. I looked through the docs but there seems to be no information on implementing it using Typescript. So far I have integrated Typescript but there is one error that is difficult to fix. This is what I have implemented so far:

pipeline.ts

import { pipeline, PipelineType } from "@huggingface/transformers";

// Use the Singleton pattern to enable lazy construction of the pipeline.
// NOTE: We wrap the class in a function to prevent code duplication (see below).
const P = () => class PipelineSingleton {
    static task: PipelineType = 'text-classification';
    static model = 'Xenova/distilbert-base-uncased-finetuned-sst-2-english';
    static instance: PipelineSingleton | null = null;

    // eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
    static async getInstance(progress_callback: Function | undefined = undefined) {
        if (!this.instance) {
            this.instance = pipeline(this.task, this.model, { progress_callback });
        }
        return this.instance;
    }
}

let PipelineSingleton: ReturnType<typeof P>;
if (process.env.NODE_ENV !== 'production') {
    // When running in development mode, attach the pipeline to the
    // global object so that it's preserved between hot reloads.
    // For more information, see https://vercel.com/guides/nextjs-prisma-postgres
    const globalWithPipeline = global as typeof global & { PipelineSingleton: ReturnType<typeof P> };

    if (!globalWithPipeline.PipelineSingleton) {
        globalWithPipeline.PipelineSingleton = P();
    }

    PipelineSingleton = globalWithPipeline.PipelineSingleton;
} else {
    PipelineSingleton = P();
}
export default PipelineSingleton;

request.ts

import { NextResponse } from 'next/server'
import PipelineSingleton from './pipeline';

export async function GET(request: Request) {
    // Extract the text parameter from the query string
    const url = new URL(request.url);
    const text = url.searchParams.get('text');
    if (!text) {
        return NextResponse.json({
            error: 'Missing text parameter',
        }, { status: 400 });
    }
    // Get the classification pipeline. When called for the first time,
    // this will load the pipeline and cache it for future use.
    const classifier = await PipelineSingleton.getInstance();  // SHOWS THE ERROR -  Type 'PipelineSingleton' has no call signatures.ts(2349)

    // Actually perform the classification
    const result = await classifier(text);

    return NextResponse.json(result);
}

The problem is in the routes.ts when calling the classifier method. Typescript shows the error:

This expression is not callable.
Type 'PipelineSingleton' has no call signatures.ts(2349)

So this probably means that my Typescript implementation is incorrect for Pipeline. Would appreciate any help on this. TIA.

[SadmanYasar]

Not sure if this is a good fix or not but I kind of fixed the type issue for classifier method by typecasting the response from getInstance method to Pipeline type. The current version (pipeline.ts same as before):

route.ts

import { NextResponse } from 'next/server'
import PipelineSingleton from './pipeline';
import { Pipeline } from '@huggingface/transformers';

export async function GET(request: Request) {
    // Extract the text parameter from the query string
    const url = new URL(request.url);
    const text = url.searchParams.get('text');
    if (!text) {
        return NextResponse.json({
            error: 'Missing text parameter',
        }, { status: 400 });
    }
    // Get the classification pipeline. When called for the first time,
    // this will load the pipeline and cache it for future use.
    const classifier = await PipelineSingleton.getInstance() as Pipeline; // UPDATED THIS LINE

    // Actually perform the classification
    const result = await classifier?.(text);

    return NextResponse.json(result);
}

[emojiiii]

const task: 'text-classification' = 'text-classification';

or

static task = 'text-classification' as const;