WebFund 2024F: Tutorial 5

From Soma-notes

This tutorial is not yet finalized.

In this tutorial you'll be playing with domdemo, a version of Assignment 1's dbdemo2 modified to use some client-side JavaScript.

Once you have the application up and running you should do the following tasks.

Tasks

  1. Change dbdemo so that it support sorting of the listed records. Specifically, it should support the following two requests:
    • /list?sort=alpha-name <--- alphabetical sort by name
    • /list?sort=ralpha-name <--- reverse alphabetical sort by name
  2. Try making the above sort happen at the database (through an SQL request) and on the server in JavaScript. Do you think it is better to have the database perform the sort, or is it better for the web server to do the sorting? Why?

Code

All code: domdemo.zip

To install, unpack, and run domdemo in the class VM: 

 wget https://homeostasis.scs.carleton.ca/~soma/webfund-2024f/code/domdemo.zip
 unzip domdemo.zip
 cd domdemo
 deno run --allow-net --allow-read --allow-write domdemo.js

domdemo.js

// SPDX-License-Identifier: GPL-3.0-or-later
// Copyright (C) 2024 Anil Somayaji
//
// dbdemo.js
// for COMP 2406 (Fall 2024), Carleton University
// 
// Initial version: October 9, 2024
//
// run with the following command:
//    deno run --allow-net --allow-read --allow-write domdemo.js
//

import { DB } from "https://deno.land/x/sqlite/mod.ts";

const status_NOT_FOUND = 404;
const status_OK = 200;
const status_NOT_IMPLEMENTED = 501;
const appTitle = "COMP 2406 DOM Demo";
const dbFile = "people.db";
const table = "people";

const db = new DB(dbFile);

db.execute(`
  CREATE TABLE IF NOT EXISTS ${table} (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT,
    city TEXT,
    country TEXT,
    birthday TEXT,
    email TEXT
  )
`);


function addRecordDB(db, table, r) {
    return db.query(`INSERT INTO ${table} ` +
                    "(name, city, country, birthday, email) " +
                    "VALUES (?, ?, ?, ?, ?)",
                    [r.name, r.city, r.country, r.birthday, r.email]);
}


function getAllRecordsDB(db, table) {
    var state = [];
    const query =
          db.prepareQuery(
              "SELECT id, name, city, country, birthday, email FROM " +
                  table + " ORDER BY name ASC LIMIT 50");

    for (const [id, name, city, country, birthday, email] of query.iter()) {
        state.push({id, name, city, country, birthday, email});
    }

    query.finalize();
    
    return state;
}


function analyzeRecordsDB(db, table) {
    var analysis = {};

    analysis.count = db.query("SELECT COUNT(*) FROM " + table);
    analysis.cityList = db.query("SELECT DISTINCT CITY FROM " + table);
    
    return analysis;
}


function MIMEtype(filename) {

    const MIME_TYPES = {
        'css': 'text/css',
        'gif': 'image/gif',
        'htm': 'text/html',
        'html': 'text/html',
        'ico': 'image/x-icon',
        'jpeg': 'image/jpeg',
        'jpg': 'image/jpeg',
        'js': 'text/javascript',
        'json': 'application/json',
        'pdf': 'application/pdf',
        'png': 'image/png',
        'txt': 'text/text'
    };

    var extension = "";
    
    if (filename) {
        extension = filename.slice(filename.lastIndexOf('.')+1).toLowerCase();
    }

    return MIME_TYPES[extension] || "application/octet-stream";
};


function template_header(title) {
    const fullTitle = appTitle + ": " + title;
    
    return `<!DOCTYPE html>
<html>
  <head>
    <title>${fullTitle}</title>
    <link rel="stylesheet" href="/style.css">
  </head>
`
}

function template_notFound(path) {
    return template_header("Page not found") +
        `<body>
<h1>Page not found</h1>

<p>Sorry, the requested page was not found.</p>
</body>
</html>
`
}


function template_addRecord(obj) {
    return template_header("Record just added") +
        `<body>
  <body>
    <h1>Person just added</h1>
    <p>Name: ${obj.name}</p>
    <p>City: ${obj.city}</p>
    <p>Country: ${obj.country}</p>
    <p>Birthday: ${obj.birthday}</p>
    <p>Email: ${obj.email}</p>
    <form method="get" action="/">
      <button type="submit">Home</button>
    </form>
  </body>
</html>
`
}


function listRecords() {
    var state = getAllRecordsDB(db, table);
    
    var response = { contentType: "application/JSON",
                     status: status_OK,
                     contents: JSON.stringify(state),
                   };

    return response;
}


async function routeGet(req) {
    const path = new URL(req.url).pathname;
    if (path === "/list") {
        return listRecords();
    } else if (path === "/analyze") {
        return await showAnalysis();
    }  else {
        return null;
    }
}


async function addRecord(req) {
    var body = await req.formData();
    var obj = { name: body.get("name"),
                city: body.get("city"),
                country: body.get("country"),
                birthday: body.get("birthday"),
                email: body.get("email") };

    addRecordDB(db, table, obj);

    var response = { contentType: "text/html",
                     status: status_OK,
                     contents: template_addRecord(obj),
                   };

    return response;
}


async function showAnalysis() {
    var analysis = analyzeRecordsDB(db, table);
    var cityList = '<li>' + analysis.cityList.join('</li> <li>') + '</li>';
    
    var analysisBody = `  <body>
  <body>
    <h1>Database analysis</h1>
    <p># Records: ${analysis.count}</p>
    <p>Cities:
      <ol>
       ${cityList}
      </ol>
    </p>

    <form method="get" action="/">
      <button type="submit">Home</button>
    </form>
  </body>
</html>`

    var contents = template_header("Analysis") + analysisBody;

    var response = { contentType: "text/html",
                     status: status_OK,
                     contents: contents,
                   };
    
    return response;
}


async function routePost(req) {
    const path = new URL(req.url).pathname;    

    if (path === "/add") {
        return await addRecord(req);
    } else {
        return null;
    }
}


async function route(req) {

    if (req.method === "GET") {
        return await routeGet(req);
    } else if (req.method === "POST") {
        return await routePost(req);
    } else {
        return {
            contents: "Method not implemented.",
            status: status_NOT_IMPLEMENTED,
            contentType: "text/plain"
        };
    }
}


async function fileData(path) {
    var contents, status, contentType;
    
    try {
        contents = await Deno.readFile("./static" + path);
        status = status_OK;
        contentType = MIMEtype(path);
    } catch (e) {
        contents = template_notFound(path);
        status = status_NOT_FOUND;
        contentType = "text/html";
    }
    
    return { contents, status, contentType };
}


async function handler(req) {

    var origpath = new URL(req.url).pathname;
    var path = origpath;
    var r =  await route(req);
    
    if (!r) {
        if (path === "/") {
            path = "/index.html";
        }
        r = await fileData(path);
    }

    console.log(`${r.status} ${req.method} ${r.contentType} ${origpath}`); 

    return new Response(r.contents,
                        {status: r.status,
                         headers: {
                             "content-type": r.contentType,
                         }});
}


const ac = new AbortController();

const server = Deno.serve(
    {
        signal: ac.signal,
        port: 8000,
        hostname: "0.0.0.0"
    },
    handler);

Deno.addSignalListener("SIGINT", () => {
    console.log("SIGINT received, terminating...");
    ac.abort();
});

server.finished.then(() => {
    console.log("Server terminating, closing database.")
    db.close();
});

static/index.html

<!DOCTYPE html>
<html>
  <head>
    <title>COMP 2406 DOM Demo</title>
    <link rel="stylesheet" href="/style.css">
  </head>
  <body>
    <h1>COMP 2406 DOM Demo</h1>

    <p>Please select what you would like to do:
      <ol>
        <li><a href="/add.html">Add a record.</a></li>
        <li><a href="/list.html">List records.</a></li>
        <li><a href="/analyze">Analyze records.</a></li>        
      </ol>
      </p>
  </body>
</html>

static/add.html

static/list.html

static/list.js


static/style.css

body {
  padding: 50px;
  font: 14px "Lucida Grande", Helvetica, Arial, sans-serif;
}

a {
  color: #00B7FF;
}
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