Full Stack Web Development - Lab 4: GETs, POSTs, and templates

1. Fork the repository to your own Github account.
2. Clone your fork to your own machine.
3. Navigate to the clone on your machine and run npm install

GETs

We already implemented a GET request in the previous labs. Remember:

app.get("/", function(request, response) {
    response.end("Hello world!");
});

app.get('/:name', function(request, response) {
    response.end('Hello, ' + request.params.name + '!');
});

Those are both GET requests!

But what if we need the user to pass in additional information? We could make the route (the "/" and "/:name" part of the code) longer. What if the information we need has some default values (i.e. not all of it is guaranteed to be there)? Are we going to need to construct every possible combination of request parameters? That seems silly.

Query Strings

You can pass additional data to a GET request with a query string in the url.

http://localhost:8000/David?lastName=Raynes&inseam=36

Specifically, the query string is after the path (/David). It starts with a question mark (?) and is followed by any number of field and value pairs in the form field=value, with each pair separated by an ampersand (&).

Like the :name parameter that was extracted by Express for us, the url query string parameters are also extracted and made available in the request object (via params, like name was).

So the lastName field could be accessed with request.params.lastName.

Use some query strings

• Open http://localhost:8000/David in your browser (or any other name, if you'd prefer).
• Add ?lastName=Raynes to the url and reload (again, feel free to try another)
• Notice how the output didn't change? Yeah, go change that so your web application reacts to this new parameter. Your application should respond by adding the specified last name to the greeting. (e.g, http://localhost:8000/David?lastName=Raynes should result in Hello, David Raynes! in your browser)

Got that working? Awesome!

Now add another parameter to the url: &inseam=36. But there's a twist: what do you do if the parameter is not present?

• If the inseam parameter is present, add an additional sentence to the output: And I understand your inseam is <inseam> inches.
• If the inseam parameter is not present, use the existing behavior to output Hello … to the browser.

For an additional challenge, try adding some logic to the inseam behavior:

• If the inseam parameter is larger than 34, add Wow, you are tall! to the output
• If the inseam parameter is smaller than 26, add How is the weather down there? to the output
• Otherwise, maintain the existing behavior

POSTs

GETs are fun and all, but we want our apps to actually do something. Step one for that is adding a form to the HTML our page delivers.

→ Insert Magic Wand Waving Here ←

Take a look at the updated index.html page by opening http://localhost:8000/. We're back to the To Do app!

Try entering a new to do item in the form a clicking the add button. Doesn't work, does it?

Implement it!

With the addition of the body-parser express middleware (already incorporated), you can access the POST data with request.body. It acts like request.params, in that it has fields and values.

Update the handler for the /todo/new url by having it output Added to do: <value of todo field>.