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Navigating large datasets using request variables in routes

From: Node.js Essential Training

Video: Navigating large datasets using request variables in routes

When you're working with a large set of data, creating a separate route for each record is just not feasible. Fortunately, Express provides a way of handling URLs matching certain patterns. In this video, we'll define routes with a bit more flexibility. Now first, let's copy from the exercise files. Go to chapter five, video three, and copy the start folder to your desktop. Now let's go to Terminal and let's install the modules for this project. Type in cd and space, and then drag the folder into Terminal.

Navigating large datasets using request variables in routes

When you're working with a large set of data, creating a separate route for each record is just not feasible. Fortunately, Express provides a way of handling URLs matching certain patterns. In this video, we'll define routes with a bit more flexibility. Now first, let's copy from the exercise files. Go to chapter five, video three, and copy the start folder to your desktop. Now let's go to Terminal and let's install the modules for this project. Type in cd and space, and then drag the folder into Terminal.

That will get us the path. And now I'm going to hit Return, and then type npm install. So now that we've installed the modules, let's start making some more changes to this application. Now, back in the exercise files, there is a folder named Data. This folder is a module containing flight information. Let's copy this folder into the start folder. Now let's start using this data. I'm going to open the start folder in sublime text. Now let's go to routes index.js. Now keep in mind here, even though we've defined this data as a module, you can power this from a database or any other data source you wanted.

In this case we're just going to use a module, because it's simple. Now let's import this data using Require. I'm going to type var and then data equals require and then I'm going to go down a level and go to slash data. So that will include all of the data in this file as an object. Back in index.js, let's remove the existing two flights. We're not going to use them anymore. Now we're going to process all the data in this file and turn these properites into objects.

To do this we're going to use a loop and then we're going to read through the object properties. So all I'm going to do here is set each flight property into an object created by the flight module. Now let's handle the functions. Shorten flight one to just flight, and then remove flight 2 entirely. So now we're going to use a URL variable to help us find the flight information. We'll be defining this in app.js in a moment. But for now we're going to use number as our variable name. This will allow us to use whatever value number is set to, to determine which flight to load up.

So here, I'm going to type, var number equals req param number. And then, later, in app.js, we'll define where that number comes from. And now, I'm going to use this number to do the lookup. We only want to display data if a valid flight number has been specified. So first, check to see if the flight information is undefined. If it is, spit back a 404 error with a simple status object. Otherwise, we want to fetch the record at that number, and get the information from the flight.

Then we'll send this information back as json. Now that with defined the function for looking up the data and returning it it's time to go back to app.js and define the route. So first, let's get rid of flight 2 entirely. And then let's change flight 1 to /:number. This is where that number variable is being defined. When someone loads a url matching this pattern and specifies a number in this spot. That number is going to be passed to our function.

Also, shorten routes.flight1 to just flight. Now, let's start up the server, and look at a couple of different records. Go back to Terminal, and type node app, and then press return. So, it looks like there's a small problem with my application. On routes/index.js, on line ten, it's not finding that flights variable. Let's go back to my application, and make sure everything's okay. So, on line 10, it's looking for the flights variable.

But the flights variable isn't being defined anywhere before line ten. The data I really want to work with is named data. All I have to do is change data to flights and it will work now. You don't necessarily have to match the name of the module with the name of the variable you use to store the results. Now let's go back to Terminal and try starting the application again. I'm going to press the up arrow on my keyboard and press Return. So now let's load up some flight data. I'm going to go to localhost at port 3000 and then I'm going to go to /flight.

And then /33. So that's now pulling up flight number 33 from LAX to Denver. And now if we go to the data you'll notice that it's the same data that's on line 16 through 22. Let's try loading up flight number 18. Again, what's being output in the browser matches whats in our data set. Defining URL variables makes routes much more flexible. By using variables we don't have to define a seperate route for each and every record in the system. In the next video we'll have a look at how to properly define routes for modifying data.

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This video is part of

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Node.js Essential Training

52 video lessons · 16329 viewers

Joseph LeBlanc
Author

 
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  1. 3m 9s
    1. Welcome
      42s
    2. What you should know before watching this course
      57s
    3. Using the exercise files
      47s
    4. Using the challenges
      43s
  2. 18m 50s
    1. Why use Node.js?
      2m 1s
    2. Choosing a Node.js installation process
      4m 56s
    3. Installing Node.js on the Mac
      2m 5s
    4. Installing Node.js on Windows
      1m 43s
    5. Installing Node.js via Node Version Manager on Ubuntu Linux
      4m 45s
    6. Installing Node.js via Node Version Manager on a Mac
      3m 20s
  3. 13m 54s
    1. Exploring language additions to the V8 JavaScript engine
      3m 38s
    2. Understanding require() and modules
      6m 39s
    3. Understanding callback execution in the event loop
      3m 37s
  4. 12m 23s
    1. Initializing Node.js projects
      2m 37s
    2. Finding an NPM
      3m 30s
    3. Maintaining projects using the npm command
      6m 16s
  5. 21m 4s
    1. Creating modules with getters and setters
      6m 33s
    2. Understanding module caching and scopes
      6m 15s
    3. Implementing JavaScript creational patterns
      5m 8s
    4. Challenge: Leveraging module caching
      55s
    5. Solution: Leveraging module caching
      2m 13s
  6. 32m 27s
    1. Starting Express applications
      3m 42s
    2. Handling GET requests returning JSON
      3m 26s
    3. Navigating large datasets using request variables in routes
      5m 4s
    4. Modifying data through PUT requests
      4m 32s
    5. Supplying middleware to modify HTTP response headers
      4m 37s
    6. Generating HTML views in Jade
      8m 9s
    7. Challenge: List all records as JSON
      37s
    8. Solution: List all records as JSON
      2m 20s
  7. 25m 37s
    1. Evaluating unit testing methodologies
      3m 8s
    2. Isolating existing code for testing
      6m 47s
    3. Supplying helpers for test data
      2m 35s
    4. Writing unit tests with Mocha
      6m 5s
    5. Simulating HTTP requests with SuperTest
      7m 2s
  8. 28m 45s
    1. Connecting to MongoDB via Mongoose
      4m 16s
    2. Defining schemas for collections in Mongoose
      3m 47s
    3. Querying MongoDB collections
      5m 32s
    4. Persisting Express sessions through MongoDB and mongo-connect
      7m 6s
    5. Logging in to Express applications using Passport
      8m 4s
  9. 21m 47s
    1. Controlling the built-in REPL
      4m 18s
    2. Constructing a custom REPL
      5m 40s
    3. Receiving command-line arguments with Optimist
      6m 14s
    4. Building command-line tools
      3m 35s
    5. Challenge: Launch a custom REPL from a command
      41s
    6. Solution: Launch a custom REPL from a command
      1m 19s
  10. 15m 46s
    1. Emitting events and attaching listeners
      5m 32s
    2. Streaming chunked data through readable streams
      2m 33s
    3. Controlling readable streams
      1m 52s
    4. Piping readable data into writable streams
      2m 10s
    5. Handling duplex streams over TCP
      3m 39s
  11. 4m 6s
    1. Deploying projects to cloud hosting services
      2m 36s
    2. Finding Node.js resources
      1m 30s

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