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URL Shortener Example

This example demonstrates how to create a URL shortener using DGate with the Request Handler module function.

First, we need to create a namespace, domain, and collection for the URL shortener.

# Create a namespace for the URL shortener
dgate-cli namespace create name=url_shortener-ns

# Create a domain with a pattern for the URL shortener
dgate-cli domain create \
    name=url_shortener-dm \
    patterns:='["url_shortener.com"]' \
    namespace=url_shortener-ns

# Create a collection for the short link documents using json schema.
dgate-cli collection create \
    schema:='{"type":"object","properties":{"url":{"type":"string"}}}' \
    name=short_link type=document namespace=url_shortener-ns

Next, we need to create the module and route for the URL shortener. FYI, we don't need a service here, since the request will be handled in the request handler module.

URL Shortener Code
import { createHash } from "dgate/crypto";
import { addDocument, getDocument } from "dgate/state";

export const requestHandler = (ctx: any) => {
    const req = ctx.request();
    const res = ctx.response();
    if (req.method == "GET") {
        const pathId = ctx.pathParam("id")
        if (!pathId) {
            res.status(400).json({ error: "id is required" })
            return;
        }
        // get the document with the ID from the collection
        return getDocument("short_link", pathId)
            .then((doc) => {
                // check if the document contains the URL
                if (!doc?.data?.url) {
                    res.status(404).json({ error: "not found" });
                } else {
                    res.redirect(doc.data.url);
                }
            })
            .catch((e) => {
                console.log("error", e, JSON.stringify(e));
                res.status(500).json({ error: e?.message });
            });
    } else if (req.method == "POST") {
        const link = req.query.get("url");
        if (!link) {
            return res.status(400).json({ error: "url is required" });
        }

        // create a new document with the hash as the ID, and the link as the data
        return addDocument({
            id: hashURL(link),
            collection: "short_link",
            // the collection schema is defined in url_shortener_test.sh
            data: { url: link },
        })
            .then(() => res.status(201).json({ id: hash }))
            .catch((e: any) => res.status(500).json({ error: e?.message }));
    } else {
        return res.status(405).json({ error: "method not allowed" });
    }
};

const hashURL = (url: string) => createHash("sha1")
    .update(url).digest("base64rawurl").slice(-8);
# Create a module for the URL shortener
dgate-cli module create \
    name=url_shortener-mod \
    payload@=$DIR/url_shortener.ts \
    namespace=url_shortener-ns

# Create a route for the URL shortener
dgate-cli route create \
    name=url_shortener \
    paths:='["/{id}", "/"]' \
    methods:='["GET","POST"]' \
    modules:='["url_shortener-mod"]' \
    namespace=url_shortener-ns
# Create a short link
http POST http://localhost:80 \
    Host:url_shortener.com \
    url=='https://dgate.io'
# Output: {"id":"abc123"}

# Test the short link
http 'http://localhost:80/abc123' \
    Host:url_shortener.com
# Output: Redirects to https://dgate.io