Subversion-Projekte lars-tiefland.prado

<com:TContent ID="body">

	<h1 id="16001">Building a Simple Currency Converter</h1>

	<p id="80053" class="block-content">This tutorial introduces the Prado web application framework and teaches

		you how to build a simple web application in a few simple steps. This

		tutorial assumes that you are familiar with PHP and you have access

		to a web server that is able to serve PHP5 scripts.

	</p>

	<p id="80054" class="block-content">In this tutorial you will build a simple web application that converts

		a dollar amount to an other currency, given the rate of that currency

		relative to the dollar. The completed application is shown bellow.

		<img src=<%~ example2.png %> class="figure" />

		You can try the application <a href="../currency-converter/index.php">locally</a> or at

		<a href="http://www.pradosoft.com/demos/currency-converter/">Pradosoft.com</a>.

		Notice that the application still functions exactly the same if javascript

		is not available on the user's browser.

	</p>

	<h1 id="download">Downloading and Installing Prado</h1>

	<p id="80055" class="block-content">To install Prado, simply download the latest version of Prado from

		<a href="http://www.pradosoft.com/">http://www.pradosoft.com</a>

		and unzip the file to a directory <b>not</b> accessible by your web server

		(you may unzip it to a directory accessible by the web server if you wish

		to see the demos and test). For further detailed installation, see the

		<a href="?page=GettingStarted.Installation">Quickstart Installation</a> guide.

	</p>

	<h1 id="16002">Creating a new Prado web Application</h1>

	<p id="80056" class="block-content">The quickest and simplest way to create a new Prado web application is

		to use the command tool <tt>prado-cli.php</tt> found in the <tt>framework</tt>

		directory of the Prado distribution.  We create a new application by running

		the  following command in your

		command prompt or console. The command creates a new directory named

		<tt>currency-converter</tt> in your current working directory.

		You may need to change to the appropriate directory

		first.

		See the <a href="?page=GettingStarted.CommandLine">Command Line Tool</a>

		for more details.

	</p>

<com:TTextHighlighter Language="text" CssClass="source block-content" id="code111">

php prado/framework/prado-cli.php -c currency-converter

</com:TTextHighlighter>

	<p id="80057" class="block-content">The above command creates the necessary directory structure and minimal

		files (including "index.php" and "Home.page") to run a Prado  web application.

		Now you can point your browser's url to the web server to serve up

		the <tt>index.php</tt> script in the <tt>currency-converter</tt> directory.

		You should see the message "Welcome to Prado!"

	</p>

	<h1 id="16003">Creating the Currency Converter User Interface</h1>

	<p id="80058" class="block-content">We start by editing the <tt>Home.page</tt> file found in the

		<tt>currency-converter/protected/pages/</tt> directory. Files ending

		with ".page" are page templates that contains HTML and Prado controls.

		We simply add two textboxes, three labels and one button as follows.

	</p>

<com:TTextHighlighter Language="prado" CssClass="source block-content" id="form1">

<com:TForm>

    <fieldset>

        <legend>Currency Converter</legend>

        <div class="rate-field">

            <com:TLabel ForControl="currencyRate" Text="Exchange Rate per $1:" />

            <com:TTextBox ID="currencyRate" />

        </div>

        <div class="dollar-field">

            <com:TLabel ForControl="dollars" Text="Dollars to Convert:" />

            <com:TTextBox ID="dollars" />

        </div>

        <div class="total-field">

            <span class="total-label">Amount in Other Currency:</span>

            <com:TLabel ID="total" CssClass="result" />

        </div>

        <div class="convert-button">

            <com:TButton Text="Convert" />

        </div>

    </fieldset>

</com:TForm>

</com:TTextHighlighter>

	<p id="refresh" class="block-content">

	If you refresh the page, you should see something similar to the following figure.

	It may not look very pretty or orderly, but we shall change that later using CSS.

	<img src=<%~ example1.png %> class="figure" />

	</p>

	<p id="80059" class="block-content">

		The first component we add is a

		<com:DocLink ClassPath="System.Web.UI.TForm" Text="TForm" />

		that basically corresponds to the HTML <tt>&lt;form&gt;</tt> element.

		In Prado, only <b>one</b> <tt>TForm</tt> element is allowed per page.

	</p>

	<p id="80060" class="block-content">The next two pair of component we add is the

		<com:DocLink ClassPath="System.Web.UI.WebControls.TLabel" Text="TLabel" />

		and

		<com:DocLink ClassPath="System.Web.UI.WebControls.TTextBox" Text="TTextBox" />

		that basically defines a label and a textbox for the user of the application

		to enter the currency exchange rate.

		The <tt>ForControl</tt> property value determines which component

		that the label is for. This allows the user of the application to click

		on the label to focus on the field (a good thing). You could have used

		a plain HTML <tt>&lt;label&gt;</tt> element to do the same thing, but

		you would have to find the correct <tt>ID</tt> of the textbox (or

		<tt>&lt;input&gt;</tt> in HTML) as Prado components may/will render the

		<tt>ID</tt> value differently in the HTML output.

	</p>

	<p id="80061" class="block-content">The next pair of components are similar and defines the textbox

		to hold the dollar value to be converted.

		The <tt>TLabel</tt> with <tt>ID</tt> value "total" defines a simple label.

		Notice that the <tt>ForControl</tt> property is absent. This means that this

		label is simply a simple label which we are going to use to display the

		converted total amount.

	</p>

	<p id="80062" class="block-content">The final component is a

		<com:DocLink ClassPath="System.Web.UI.WebControls.TButton" Text="TButton" />

		that the user will click to calculate the results. The <tt>Text</tt>

		property sets the button label.

	</p>

	<h1 id="16004">Implementing Currency Conversion</h1>

	<p id="80063" class="block-content">If you tried clicking on the "Convert" button then the page will refresh

		and does not do anything else. For the button to do some work, we need

		to add a "Home.php" to where "Home.page" is. The <tt>Home</tt> class

		should extends the

		<com:DocLink ClassPath="System.Web.UI.TPage" Text="TPage" />, the default base

		class for all Prado pages.

	</p>

<com:TTextHighlighter Language="php" CssClass="source block-content" id="code3">

<?php

class Home extends TPage

{

}

?>

</com:TTextHighlighter>

	<p id="1111" class="block-content">

		Prado uses PHP's <tt>__autoload</tt> method to load classes. The convention

		is to use the class name with ".php" extension as filename.

	</p>

	<p id="80064" class="block-content">So far there is nothing interesting about Prado, we just declared some

		"web components" in some template file named Home.page and created

		a "Home.php" file with a <tt>Home</tt> class. The more interesting

		bits are in Prado's event-driven architecture as we shall see next.

	</p>

	<p id="80065" class="block-content">We want that when the user click on the "Convert" button, we take the

		values in the textbox, do some calculation and present the user with

		the converted total. To handle the user clicking of the "Convert" button

		we simply add an <tt>OnClick</tt> property to the "Convert" button in

	 	the "Home.page" template and add a corresponding event handler method

		in the "Home.php".

	</p>

<com:TTextHighlighter Language="prado" CssClass="source block-content" id="code4">

<com:TButton Text="Convert" OnClick="convert_clicked" />

</com:TTextHighlighter>

	<p id="222" class="block-content">

		The value of the <tt>OnClick</tt>, "<tt>convert_clicked</tt>", will be the method

		name in the "Home.php" that will called when the user clicks on the

		"Convert" button.

	</p>

<com:TTextHighlighter Language="php" CssClass="source block-content" id="code5">

class Home extends TPage

{

    public function convert_clicked($sender, $param)

    {

        $rate = floatval($this->currencyRate->Text);

        $dollars = floatval($this->dollars->Text);

        $this->total->Text = $rate * $dollars;

    }

}

</com:TTextHighlighter>

<div id="3332" class="block-content">

	<p id="333">

		If you run the application in your web browser, enter some values and click

		the "Convert" button then you should see that calculated value displayed next

		to the "Amount in Other Currency" label.

	</p>

	<p id="80066">In the "<tt>convert_clicked</tt>" method the first parameter, <tt>$sender</tt>,

		corresponds to the object that raised the event, in this case,

		the "Convert" button. The second parameter, <tt>$param</tt> contains

		any additional data that the <tt>$sender</tt> object may wish to have added.

	</p>

	<p id="80067">We shall now examine, the three lines that implements the simply currency

		conversion in the "<tt>convert_clicked</tt>" method.

	</p>

</div>

<com:TTextHighlighter Language="php" CssClass="source block-content" id="code6" >

$rate = floatval($this->currencyRate->Text);

</com:TTextHighlighter>

	<p id="444" class="block-content">

		The statement <tt>$this->currencyRate</tt> corresponds to the

		<tt>TTextBox</tt> component with <tt>ID</tt> value "currencyRate" in the

		"Home.page" template. The <tt>Text</tt> property of the <tt>TTextBox</tt>

		contains the value that the user entered. So, we obtain this

		value by <tt>$this->currencyRate->Text</tt> which we convert the

		value to a float value.

	</p>

<com:TTextHighlighter Language="php" CssClass="source block-content" id="code7">

$dollars = floatval($this->dollars->Text);

</com:TTextHighlighter>

<div id="5551" class="block-content">

	<p id="555">

		The next line does a similar things, it takes the user value from

		the <tt>TTextBox</tt> with <tt>ID</tt> value "dollars and converts it to

		a float value.

	</p>

	<p id="80068">The third line calculates the new amount and set this value in the

		<tt>Text</tt> property of the <tt>TLabel</tt> with <tt>ID="total"</tt>.

		Thus, we display the new amount to the user in the label.

	</p>

</div>

<com:TTextHighlighter Language="php" CssClass="source block-content" id="code8">

$this->total->Text = $rate * $dollars;

</com:TTextHighlighter>

	<h1 id="16005">Adding Validation</h1>

	<p id="80069" class="block-content">The way we convert the user entered value to float ensures that the

		total amount is always a number. So the user is free to enter what

		ever they like, they could even enter letters. The user's experience

		in using the application can be improved by adding validators

		to inform the user of the allowed values in the currency rate and the

		amount to be calcuated.

	</p>

	<p id="80070">For the currency rate, we should ensure that</p>

		<ol id="o111" class="block-content">

			<li>the user enters a value,</li>

			<li>the currency rate is a valid number,</li>

			<li>the currency rate is positive.</li>

		</ol>

	<p id="666" class="block-content">

	 To ensure 1 we add one

	<com:DocLink ClassPath="System.Web.UI.WebControls.TRequiredFieldValidator" Text="TRequiredFieldValidator" />. To ensure 2 and 3, we add one

	<com:DocLink ClassPath="System.Web.UI.WebControls.TCompareValidator" Text="TCompareValidator" />. We may add these validators any where within

	the "Home.page" template. Further details regarding these validator and other

	validators can be found in the

	<a href="?page=Controls.Validation">Validation Controls</a> page.

	</p>

<com:TTextHighlighter Language="prado" CssClass="source block-content" id="code9">

<com:TRequiredFieldValidator

	ControlToValidate="currencyRate"

	ErrorMessage="Please enter a currency rate." />

<com:TCompareValidator

	ControlToValidate="currencyRate"

	DataType="Float"

	ValueToCompare="0"

	Operator="GreaterThan"

	ErrorMessage="Please enter a positive currency rate." />

</com:TTextHighlighter>

	<p id="80071" >For the amount to be calculated, we should ensure that</p>

		<ol id="o222" class="block-content">

			<li>the user enters a value,</li>

			<li>the value is a valid number (not including any currency or dollar signs).</li>

		</ol>

	<p id="777" class="block-content">

	To ensure 1 we just add another <tt>TRequiredFieldValidator</tt>, for 2

	we could use a

	<com:DocLink ClassPath="System.Web.UI.WebControls.TDataTypeValidator" Text="TDataTypeValidator" />. For simplicity we only allow the user to enter

	a number for the amount they wish to convert.

	</p>

<com:TTextHighlighter Language="prado" CssClass="source block-content" id="code9a">

<com:TRequiredFieldValidator

	ControlToValidate="dollars"

	ErrorMessage="Please enter the amount you wish to calculate." />

<com:TDataTypeValidator

	ControlToValidate="dollars"

	DataType="Float"

	ErrorMessage="Please enter a number." />

</com:TTextHighlighter>

	</p>

	<p id="80072" class="block-content">Now if you try to enter some invalid data in the application or left out

		any of the fields the validators will be activated and present the user

		with error messages. Notice that the error messages are presented

		without reloading the page. Prado's validators by default validates

		using both javascript and server side. The server side validation

		is <b>always performed</b>. For the server side, we

		should skip the calculation if the validators are not satisfied. This can

		done as follows.

	</p>

<com:TTextHighlighter Language="php" CssClass="source block-content" id="code10" >

public function convert_clicked($sender, $param)

{

    if($this->Page->IsValid)

    {

        $rate = floatval($this->currencyRate->Text);

        $dollars = floatval($this->dollars->Text);

        $this->total->Text = $rate * $dollars;

    }

}

</com:TTextHighlighter>

	<h1 id="16006">Improve User Experience With Active Controls</h1>

	<com:RequiresVersion Version="3.1a" />

	<p id="80073" class="block-content">In this simple application we may further improve the user experience

		by increasing the responsiveness of the application. One way to achieve

		a faster response is calculate and present the results without reloading

		the whole page.

	</p>

	<p id="80074" class="block-content">We can replace the <tt>TButton</tt> with the Active Control counter part,

		<com:DocLink ClassPath="System.Web.UI.ActiveControls.TActiveButton" Text="TActiveButton" />,

		that can trigger a server side click event without reloading the page.

		In addition, we can change the "totals" <tt>TLabel</tt> with the

		Active Control counter part,

		<com:DocLink ClassPath="System.Web.UI.ActiveControls.TActiveLabel" Text="TActiveLabel" />, such that the server side can update the browser without

		reloading the page.

	</p>

<com:TTextHighlighter Language="prado" CssClass="source block-content" id="code11">

<div class="total-field">

    <span class="total-label">Amount in Other Currency:</span>

         <com:TActiveLabel ID="total" CssClass="result" />

    </div>

    <div class="convert-button">

        <com:TActiveButton Text="Convert" OnClick="convert_clicked" />

</div>

</com:TTextHighlighter>

	<p id="1232" class="block-content">

		The server side logic remains the same, we just need to import the

		Active Controls name space as they are not included by default. We

		add the following line to the begin of "Home.php".

	</p>

<com:TTextHighlighter Language="php" CssClass="source block-content" id="code12">

Prado::using('System.Web.UI.ActiveControls.*');

</com:TTextHighlighter>

	<p id="80075" class="block-content">If you try the application now, you may notice that the page no longer

		needs to reload to calculate and display the converted total amount.

		However, since there is not page reload, there is no indication or not obvious

		that by clicking on the "Convert" button any has happened.

		We can further refine the user experience by change the text of "total" label

		to "calculating..." when the user clicks on the "Convert" button. The text of

		the "total" label will still be updated with the new calculate amount as before.

	</p>

	<p id="80076" class="block-content">To indicate that the calculation is in progress, we can change the text

		of the "total" label as follows. We add a <tt>ClientSide.OnLoading</tt> property

		to the "Convert" button (since this button is responsible for requesting

		the calculation).

	</p>

<com:TTextHighlighter Language="prado" CssClass="source block-content" id="code13">

<com:TActiveButton Text="Convert" OnClick="convert_clicked" >

    <prop:ClientSide.OnLoading>

        $('<%= $this->total->ClientID %>').innerHTML = "calculating..."

    </prop:ClientSide.OnLoading>

</com:TActiveButton>

</com:TTextHighlighter>

	<p id="80077" class="block-content">The <tt>ClientSide.OnLoading</tt> and various

	<com:DocLink ClassPath="System.Web.UI.ActiveControls.TCallbackClientSide" Text="other properties" /> accept a javascript block as their content or value.

	The javascript code <tt>$('...')</tt> is a javascript function that is

	equivalent to <tt>document.getElementById('...')</tt> that takes a string

	with the ID of an HTML element. Since Prado renders its components's IDs, we need

	to use the rendered ID of the "total" label, that is, <tt>$this->total->ClientID</tt>. We place this bit of code within a <tt>&lt;%= %&gt;</tt> to obtain the rendered HTML ID for the "total" label. The rest of the

	javascript code <tt>innerHTML = "calculating..."</tt> simply changes

	the content of the "total" label.

	</p>

	<h1 id="16007">Adding Final Touches</h1>

	<p id="80078" class="block-content">So far we have built a simple currency converter web application with

		little attention of the looks and feel. Now we can add a stylesheet

		to improve the overall appearance of the application. We can simply

		add the stylesheet inline with the template code or we may create

		a "theme".

	</p>

	<p id="80079" class="block-content">To create and use a theme with Prado applications, we simply create a new

		directory "themes/Basic" in the <tt>currency-converter</tt> directory.

		You may need to create the <tt>themes</tt> directory first. Any

		directory within the <tt>themes</tt> are considered as a theme with the

		name of the theme being the directory name. See the

		<a href="?page=Advanced.Themes">Themes and Skins</a> for further details.

	</p>

	<p id="80080" class="block-content">We simply create a CSS file named "common.css" and save it in the

		<tt>themes/Basic</tt> directory. Then we add the following code

		to the beginning of "Home.page" (we add a little more HTML as well).

	</p>

<com:TTextHighlighter Language="prado" CssClass="source block-content" id="code14">

<%@ Theme="Basic" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"

"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" >

<com:THead Title="Currency Converter" />

<body>

</com:TTextHighlighter>

	<p id="4334" class="block-content">

		The first line <tt>&lt;%@ Theme="Basic" %&gt;</tt> defines the

		theme to be used for this page. The

		<com:DocLink ClassPath="System.Web.UI.WebControls.THead" Text="THead" />

		corresponds to the HTML <tt>&lt;head&gt;</tt> element. In addition

		to display the <tt>Title</tt> property by the <tt>THead</tt>, all CSS

		files in the <tt>themes/Basic</tt> directory are also rendered/linked

		for the current page. Our final currency converter web application

		looks like the following.

		<img src=<%~ example2.png %> class="figure" />

		This completes introduction tutorial to the Prado web application framework.

	</p>

<div class="last-modified">$Id: CurrencyConverter.page 1846 2007-04-07 10:35:16Z wei $</div></com:TContent>