TweetFollow Us on Twitter

Getting Started with REALBasic-Part 4

Volume Number: 25 (2009)
Issue Number: 01
Column Tag: Programming

Getting Started with REALBasic-Part 4

Designing the Application

by Norman Palardy

REALbasic is a Rapid Application Development (RAD) tool from REALSoftware. In the last column we implemented a big chunk of the database for our stock tracker application. REALbasic 4 and 4.1 have been released in the interim and we'll move up to using that version as there are a number of bug fixes and improvements in it.

Back to it

I've been extremely busy getting the last two releases of REALbasic out and apologize to everyone for the hiatus.

This time the focus is going to be on getting several stocks symbols into the database, retrieving quotes for each of them and storing the data back in the database.

Right now the database is cleaned out every time we start up. While it makes for a nice clean starting point, it's really not that useful in an application that is designed to store data for a long period of time.

We'll need to start by looking at the things that happen when we start up our application. If the database already exists, that's great and we don't need to worry about doing much more. If it doesn't, we need to create it.

But, how are we going to know what database the user wants to use and where it might be?

There are at least a couple ways of dealing with this. One would be to read a preference from some repository like a preferences file and use that. The other would be to use a "well defined place" to store this. Conveniently on OS X and Windows there is a convention for exactly this purpose. On OS X this is in the users Application Data directory. And REALbasic makes it easy to access.

So let's alter the App.Open event to handle all this for us.

// if the Application Data directory has a directory for our app
// and the directory holds our database then we should use that one
if SpecialFolder.ApplicationData.Child(app.kAppName).Exists = true _
and SpecialFolder.ApplicationData.Child(app.kAppName).Child(kDBName).Exists = true then
  app.db.DatabaseFile =  SpecialFolder.ApplicationData.Child(app.kAppName).Child(kDBName)
    app.db = new REALSQLDatabase
    app.db.DatabaseFile = SpecialFolder.ApplicationData.Child(app.kAppName).Child(kDBName)
    // see if we can open the database
    if app.db.Connect() <> true then
      // oh oh .... something bad 
      app.db = nil
      msgbox "Unable to connect to database"
    end if
    // hmm is there a directory for our application ?
    if SpecialFolder.ApplicationData.Child(app.kAppName).Exists <> true then
      // no so better create one
    end if
    // is there a database ?
    if SpecialFolder.ApplicationData.Child(app.kAppName).Child( <> true then
      // no database file
      // create a new instance REASQLDatabase Class
      app.db = new REALSQLDatabase
      // set the file to the one in the users Library > Application Support
      app.db.DatabaseFile =  SpecialFolder.ApplicationData.Child(app.kAppName).Child(app.kDBName)
      // create the container database file
      if app.db.CreateDatabaseFile() <> true then
        // something bad      
        app.db = nil
        msgbox "Unable to create database"
        // ok so now create the database tables
      end if
    end if
  end if  

As you look this code over you should notice that I've used two constants for the name of the directory, App.kAppName, and the name of the database, App.kDBName.

Add a constant to the App instance in your project and name it kAppName. Set the value for it to MyStockApp. And add the second constant, kDBName, and set its value to "MyStocks.db"

You'll also need to create an empty method in the App instance called CreateDBTables.

We'll fill this one in later.

If you run the app at this point you should find things still work, but you are no longer prompted to select a database. Instead one is automatically place in ~/Library/Application Support/MyStockApp called MyStocks.db.

This is exactly as it should be.

This new database is completely empty though. It doesn't even have the tables we need and this is what we'll fix in the new CreateDBTables method.

But how to get the same definitions we came up with before? It turns out that OS X includes sqlite and we can actually get it to dump out all the SQL we'll need to create the database. Open (located in /Applications/Utilities) and type in


and then drag the database into the terminal window. sqlite will open the database and then you can run the one SQL command needed

select sql from sqlite_master where type = 'table' 

In my case this gives me the exact sql I need to create the tables

CREATE TABLE StocksOfInterest(Name Varchar, Symbol VarChar)
CREATE TABLE StockQuote(Symbol Text, Price Double, quoteDateTime Timestamp)

I can take this and incorporate it into the CreateDBTables method as follows:

  app.db.sqlexecute("CREATE TABLE StocksOfInterest(Name Varchar, Symbol VarChar)")
  app.db.sqlexecute("CREATE TABLE StockQuote(Symbol Text, Price Double, quoteDateTime Timestamp)")

Note that what we have is one language, REALbasic, telling another tool, sqlite, to execute a command in it's language, SQL, that it understands and can do something useful with.

REALbasic does not know anything about SQL. It's just strings of characters to REALbasic.

And SQL knows nothing about REALbasic and it's variables, methods, or anything else.

This is very important to realize that they know nothing about each other and that getting them to work properly together is sometimes and exercise in making sure the string you've created in your REALbasic code IS the right SQL. Sometimes testing things out by hand is the only good way to figure out where your error is if you have trouble. This makes the inclusion of sqlite very handy on OS X.

In fact, let's test this out. If you have a database in ~/Library/Application Support/MyStockApp then delete it and run the program again. Once it has run, quit and then, in Terminal, ahave sqlite3 ope nthe newly created database.

Again use the sql command

select sql from sqlite_master where type = 'table' 

and you should see that there are the two commands that we had in our application to create the tables. We've now created the tables programmatically.

Moving On

Now that we have created the database lets see how we can get quotes into it in an automated way.

I happen to like using Yahoo because the service is easy to grab data from. That said you can probably use whatever service you want. Some will be easier and some more difficult.

What we need to know is how to get the "current" quote from Yahoo for a specific stock in a form we can do something useful with.

Yahoo has a nice simple URL for this exact thing<symbol>

In a browser if you replace <symbol> with AAPL this will download a file to your machine that is a csv delimited text file with the most recent quote for AAPL. You can alter a number of other attributes to get other data but this is the form we want.

So what we need to do is get REALbasic to go to this URL, get the data and parse it apart and put it in our database and the redisplay the data. And to do this every "once in a while". Nothing to it :)

It turns out that REALbasic has just the thing for this task: the HTTP socket. There are two ways to use this; synchronously and asynchronously. The simpler of the two is synchronously and so that's what we'll use.

But how to get REALbasic to do this "once in a while"? Again, REALbasic has a nice object called a Timer that can be used to do things periodically. Note that timers are "patient" in that they try to work as close to the timing you set but if something else is really busy they will wait until there is a chance for them to do their thing. So they are reasonably accurate in running periodically but not 100% precise.

We'll make use of the timer as it is good enough for what we need.

Open the wStocks window and scroll down the list of controls, select the timer, and drag one onto the workspace.

Figure 1 - Selecting the timer

Figure 2 - Timer placed on Workspace

A timer has several useful properties that we will want to adjust.

Figure 3 - Timer Properties

The Mode property controls whether the timer is on and active or not and if it is one whether the timer runs and performs its action once, or repeatedly. You can toggle this setting in your program as well as setting it directly in the IDE.

The other setting is the Period, or minimum time between the timer performing its action. If the Timer is set to run its action multiple times this will be the minimum time between actions. Careful though, as the period is specified in milliseconds and the setting shown above is only 1 second. We should set this to something more like 300,000, which is every 5 minutes.

Let's make a method that gets the stock data from the web and inserts into the database first.

Open the App instance and create a new method called GetStockPrice. This should take one parameter; the Symbol of the stock we want the quote for. Mine looks like

Sub GetStockPrice(symbol as string)
  dim HTTP as HTTPSocket
  dim data as string
  if trim(symbol) = "" then return
  // we're going to grab the price from Yahoo
  // the URL is like
  dim url as string = "" + symbol
// make a new HTTP socket to use
  http = new HTTPSocket
// tell it to get the data and wait no more than 30 seconds for a reply
  data = HTTP.Get(url, 30)
  // the data we get back is like
  // "AAPL",117.05,"8/16/2007","4:00pm",-2.85,116.91,118.50,111.62,66667828
// pull out the price (the seccond field)
  dim stockPrice as double = val(nthfield(data,",", 2) )
// and use our already existing method to put it in the database
  app.AddDataForStock Symbol, stockPrice , new Date
End Sub

Now if you double click the Timer we can add the code that will grab the stock quotes every time the timer runs its Action. In the timer simply put


This will grab the new quotes for AAPL every 5 minutes. But we also want to update the display with those. And eventually we want to be able to make this grab a list of stocks, not just one or two.

First let's deal with displaying the stock quotes.

If you look in the open event for the listbox that shows the stock quotes it has a bunch of code already that we just need to move somewhere else so we can have it redisplay things on demand, not just when the window opens. This is a perfect opportunity to refactor this code so it's more generally useful.

Start by creating a new method called ReDisplayData.

Take all the code from the Open Event of the listbox and move it into this new method. You'll have to change every place it says "me." to "lstStocks."

Then, in the Listbox open event simply have it call ReDisplayData so it looks like


And add a call to RedisplayData at the end of the timer's actions as well so it looks like



If you run now you should see the display get a new entry for AAPL every few minutes. However, the display of the stock proce might look a little odd. On mine, as of this writing it shows "9.74000000056e+1".

So lets change Redisplay data a little.

If you look at the line that reads

lstStocks.Cell(lstStocks.LastIndex,2) = rs.Field("Price").StringValue

and change it to

lstStocks.Cell(lstStocks.LastIndex,2) = Format(rs.Field("Price").DoubleValue,"#.00")

This will make things look right. The original line just used an implicit conversion of a floating point double to a string. The default is to give you scientific notation. The FORMAT command gives us control over how the conversion to a string occurs and so it looks better.

Lots of Progress

Just in this short sprint we've made a lot of progress. We've made the application create it's own database if none existed. We've added the ability to periodically grab new quotes from the internet and redisplay them. And, when you quit and restart your application it will start up with all the data you had before. Not bad for this time around.

There are some things you might want to look into until next time.

ReDisplayData just keeps adding to the list shown all the time and so if you leave this application running for a long time it will eventually have an enormously long list of items displayed. You might see if you can chnage that.

And for the really adventurous, see if you can change JUST the SQL that ReDisplayData uses so it only grabs the latest quote instead of all of them.

Norman Palardy has worked with SQL databases since 1992, and has programmed in C, C++, Java, REALbasic and other languages on a wide variety of platforms. In his 15+ years of IT experience, Norman has developed innovative and award-winning applications for TransCanada Pipelines, Minerva Technologies (now XWave), Zymeta Corporation, and the dining and entertainment industry. He holds a BSc from the University of Calgary in Alberta. He's also a founder of the Association of REALbasic Professionals ( and currently works for REAL Software


Community Search:
MacTech Search:

Software Updates via MacUpdate

MacPilot 8.0 - Enable over 1,200 hidden...
MacPilot gives you the power of UNIX and the simplicity of Macintosh, which means a phenomenal amount of untapped power in your hands! Use MacPilot to unlock over 1,200 features, and access them all... Read more
Typinator 6.7 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more
Adobe Lightroom 6.2 - Import, develop, a...
Adobe Lightroom is available as part of Adobe Creative Cloud for as little as $9.99/month bundled with Photoshop CC as part of the photography package. Lightroom 6 is also available for purchase as a... Read more
ForeverSave 2.1.4 - Universal auto-save...
ForeverSave auto-saves all documents you're working on while simultaneously doing backup versioning in the background. Lost data can be quickly restored at any time. Losing data, caused by... Read more
VueScan 9.5.27 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
AirPort Utility 6.3.6 - Set up and manag...
Note: Most recent release available only within OS X 10.11 El Capitan update. Use AirPort Utility to set up and manage your Wi-Fi network and AirPort base stations, including AirPort Express, AirPort... Read more
Quicksilver 1.3.1 - Application launcher...
Quicksilver is a light, fast and free Mac application that gives you the power to control your Mac with keystrokes alone. Quicksilver allows you to find what you need quickly and easily, then act... Read more
Tidy Up (Five Users) 4.1.5 - Find duplic...
Tidy Up is a complete duplicate finder and disk-tidiness utility. With Tidy Up you can search for duplicate files and packages by the owner application, content, type, creator, extension, time... Read more
Mellel 3.4.3 - The word processor of cho...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
Skype - Voice-over-internet p...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more

Swords & Crossbones: An Epic Pirate...
Swords & Crossbones: An Epic Pirate Story 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: | Read more »
Camel Up (Games)
Camel Up 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: | Read more »
The Martian: Bring Him Home (Games)
The Martian: Bring Him Home 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Based on the best selling novel and critically acclaimed film, THE MARTIAN tells the story of Astronaut Mark... | Read more »
This Week at 148Apps: September 21-30, 2...
Leap Into Fall With 148Apps How do you know what apps are worth your time and money? Just look to the review team at 148Apps. We sort through the chaos and find the apps you're looking for. The ones we love become Editor’s Choice, standing out above... | Read more »
Tweetbot 4 for Twitter (Social Networki...
Tweetbot 4 for Twitter 4.0 Device: iOS Universal Category: Social Networking Price: $4.99, Version: 4.0 (iTunes) Description: *** 50% off for a limited time. *** | Read more »
Mori (Games)
Mori 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Stop, rewind and unwind with Mori. Time is always running, take a moment to take control. Mori is an action puzzle game about infinitely... | Read more »
100 Years' War (Games)
100 Years' War 1.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: | Read more »
Tower in the Sky (Games)
Tower in the Sky 0.0.60 Device: iOS Universal Category: Games Price: $1.99, Version: 0.0.60 (iTunes) Description: | Read more »
hocus. (Games)
hocus. 1.0.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0.0 (iTunes) Description: New, polished, mind-bending, minimal puzzle game with dozens of levels and extra-ordinary design Features:- Beautifully crafted... | Read more »
Mos Speedrun 2 (Games)
Mos Speedrun 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Mos is back, in her biggest and most exciting adventure ever! Wall-jump to victory through 30 mysterious, action packed levels... | Read more »

Price Scanner via

13-inch 2.5GHz MacBook Pro (refurbished) avai...
Apple has Certified Refurbished 13″ 2.5GHz MacBook Pros available for $829, or $270 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.5GHz MacBook Pros... Read more
27-inch 3.2GHz iMac on sale for $1689, save $...
Adorama has the 27″ 3.2GHz iMac on sale for $1689 including free shipping plus NY & NJ sales tax only. Their price is $110 off MSRP. Read more
12-inch Retina MacBooks on sale for up to $12...
B&H Photo has 12″ Retina MacBooks in stock today and on sale for up to $120 off MSRP. B&H will include free shipping, and there is NY sales tax only: - 12″ 1.1GHz Gray Retina MacBook: $1224 $... Read more
Tablets Shaping Up for Growth in 2016 – Strat...
Observing that Apple, Samsung, and Microsoft have refocused what tablet computers can do, market analysis firm Strategy Analytics believes there is immense opportunity for new and replacement sales... Read more
Apple Interbrand’s Number One Most Valuable G...
Apple and Google hold aced #1 and #2 spots respectively in Interbrand’s 2015 Best Global Brands Report, leading all tech brands that now comprise more than a third of the entire rankings value.... Read more
Apple offering refurbished 2015 13-inch Retin...
Apple is offering Certified Refurbished 2015 13″ Retina MacBook Pros for up to $270 (15%) off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: -... Read more
Apple refurbished 2015 MacBook Airs available...
Apple has Certified Refurbished 2015 11″ and 13″ MacBook Airs (the latest models), available for up to $180 off the cost of new models. An Apple one-year warranty is included with each MacBook, and... Read more
Adobe Photoshop Elements 14 Gets Haze Removal...
The latest iteration of Adobe’s powerful consumer image editing appliction Photoshop Elements 14 analyzes your photo and removes background haze, so your shot looks sharp all the way to the horizon... Read more
Apple refurbished 15-inch Retina MacBook Pros...
Apple has Certified Refurbished 2015 15″ Retina MacBook Pros available for up to $380 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 15″ 2... Read more
21-inch iMacs on sale for up to $120 off MSRP
B&H Photo has 21″ iMacs on sale for up to $100 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $1029.99 $70 off - 21″ 2.7GHz iMac: $1229 $70 off - 21″ 2.9GHz iMac: $... Read more

Jobs Board

Touch Validation Design (EE) - *Apple* Watc...
**Job Summary** Help launch next-generation Touch Technologies in Apple products. The Touch Technology team develops cutting-edge Touch solutions and technologies that Read more
WW Sales Strategy & Program Manager, *Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
*Apple* TV Product Design Internship (Spring...
…the mechanical design effort associated with creating world-class products with the Apple TV PD Group. Responsibilities will include working closely with manufacturing, Read more
Product Design Engineer - *Apple* Watch - A...
**Job Summary** Product Design Engineer - WATCH ( Apple Watch) Be an integral part of a small and visible team of world-class Mechanical Engineers making Apple 's Read more
Senior Software System App Engineer, *Apple*...
**Job Summary** The Apple Watch system application team is looking for great software engineers who are comfortable working across all levels of the software stack. From Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.