Simple helper you can use to communicate with Payload CMS from your application via their REST API. Authorization via API key needs to be enabled in your users collection. More on enabling API keys here: https://payloadcms.com/docs/authentication/config#api-keys

PayloadCommunicator.ts

import qs from 'qs';

export const cmsURL = "cms URL without the / at the end";
export const apiKey = "yourAPIkey";

export async function getDocuments (collectionName: string, whereQuery?) {
    if (whereQuery) {
        const stringifiedQuery = qs.stringify({
            where: whereQuery 
        }, { addQueryPrefix: true });
    
        const potentialFoundDocument = await (await fetch(`${cmsURL}/api/${collectionName}${stringifiedQuery}`, {
            method: 'GET',
            headers: {
                "Content-Type": "application/json",
                Authorization: `users API-Key ${apiKey}`
            },
        })).json()
        return potentialFoundDocument;
    } else {
        const potentialFoundDocument = await (await fetch(`${cmsURL}/api/${collectionName}`, {
            method: 'GET',
            headers: {
                "Content-Type": "application/json",
                Authorization: `users API-Key ${apiKey}`
            },
        })).json()
        return potentialFoundDocument;
    }
}

export async function getDocumentByID (collectionName: string, id: string) {
    const potentialFoundDocument  = await (await fetch(`${cmsURL}/api/${collectionName}/${id}`, {
        method: 'GET',
        headers: {
            "Content-Type": "application/json",
            Authorization: `users API-Key ${apiKey}`
        },
    })).json()
    return potentialFoundDocument;
}

export async function newDocument (collectionName: string, initialFields) {
    const requestResponse = await (await fetch(`${cmsURL}/api/${collectionName}`, {
        method: 'POST',
        headers: {
            "Content-Type": "application/json",
            Authorization: `users API-Key ${apiKey}`
        },
        body: JSON.stringify(initialFields),
    })).json();
    return requestResponse;
}

export async function updateDocument (collectionName: string, documentToUpdateID: string, updatedFields) {
    const requestResponse = await (await fetch(`${cmsURL}/api/${collectionName}/${documentToUpdateID}`, {
        method: 'PATCH',
        headers: {
            "Content-Type": "application/json",
            Authorization: `users API-Key ${apiKey}`
        },

        body: JSON.stringify(updatedFields),
    })).json();
    return requestResponse;
}

UsageExample.ts

import { getDocuments, getDocumentByID, newDocument, updateDocument } from './PayloadCommunicator';

export async function example (someObject) {

    // Getting documents via where filter
    const potentialFoundCategory = await getDocuments('categories', {
        name: {
            equals: someObject.category.name,
        },
    })

    // Getting document by ID
    const potentialFoundCategory2 = await getDocumentByID('categories', '63ad03ec20022d8e1b03cd21')

    // Creating new document
    const newArticleResponse = await newDocument('articles', {
        path: someObject.path,
        timestamp: someObject.timestamp,
        category_relationship: potentialFoundCategory.docs[0].id,
    });

   // Updating document:
   const updatedArticleResponse = await updateDocument('articles', newArticleResponse.doc.id, {
        article_id_in_category: potentialFoundCategory.docs[0].article_count + 1,
    });

}