if-else VS. XML

Ich denke jeder Entwickler hatte schon einmal die Situation, dass er verschiedene Abhängigkeiten abfangen musste. Dies ist mit if-else bzw. switch möglich, jedoch erfordert es bei jeder Änderung der Logik das Änderen des Quellcodes und dieser steht bei einer kompilierten Anwendung oft nicht zur Verfügung. Anbei ein Beispiel das ganze per XML zu lösen. Umgebung für dieses Beispiel ist Framework 3.5 mit Linq. Ich habe zur Ausgabe Dropdownlists verwendet.

I think every developer had already the situation, that he needed to display or catch certain dependencies. With if-else or switch you can do that, but in case of changes to the logic, you need to get into the source code and change that. Sometimes you don't have the source code or just a compiled version. You can handle this with XML. The environment of this example is framework 3.5 with Linq. I used for output dropdown-lists.

aspx - Seite

<form id="form1" runat="server">
<div>
<asp:DropDownList ID="Ebene1" AutoPostBack="true" OnSelectedIndexChanged="LoadSecondMenu" runat="server" /><br />
<asp:DropDownList ID="Ebene2" AutoPostBack="true" OnSelectedIndexChanged="LoadThirdMenu" runat="server" /><br />
<asp:DropDownList ID="Ebene3" AutoPostBack="true" OnSelectedIndexChanged="GetValue" runat="server" /><br />
<asp:Literal ID="MyLit" runat="server" /><br />
</div>
</form>

Codebehind

protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
LoadFirstMenu();
}
}

protected void LoadFirstMenu()
{
Ebene1.Items.Add(new ListItem("Auswahl", "Auswahl"));
XDocument myDocument = XDocument.Load(MapPath("XMLTest.xml"));
var myQuery = from strResult in myDocument.Descendants("Logic").Descendants("Parent") select strResult.Attribute("ID").Value;
foreach (var Item in myQuery)
{
Ebene1.Items.Add(new ListItem(Item, Item));
}
Ebene2.Items.Clear();
Ebene3.Items.Clear();
}

protected void LoadSecondMenu(object sender, EventArgs e)
{
Ebene2.Items.Clear();
if (Ebene1.SelectedItem.Value != "Auswahl")
{
Ebene2.Items.Add(new ListItem("Auswahl", "Auswahl"));
XDocument myDocument = XDocument.Load(MapPath("XMLTest.xml"));
var myQuery = from strResult in myDocument.Descendants("Logic").Descendants("Parent").Descendants("Child") where strResult.Parent.Attribute("ID").Value == Ebene1.SelectedItem.Value select strResult.Attribute("ID").Value;
foreach (var Item in myQuery)
{
Ebene2.Items.Add(new ListItem(Item, Item));
}
}
Ebene3.Items.Clear();
}

protected void LoadThirdMenu(object sender, EventArgs e)
{
if (Ebene2.SelectedItem.Value != "Auswahl")
{
Ebene3.Items.Add(new ListItem("Auswahl", "Auswahl"));
XDocument myDocument = XDocument.Load(MapPath("XMLTest.xml"));
var myQuery = from strResult in myDocument.Descendants("Logic").Descendants("Parent").Descendants("Child").Descendants("Child") where strResult.Parent.Attribute("ID").Value == Ebene2.SelectedItem.Value select strResult.Attribute("ID").Value;
foreach (var Item in myQuery)
{
Ebene3.Items.Add(new ListItem(Item, Item));
}
}
}

protected void GetValue(object sender, EventArgs e)
{
if (Ebene3.SelectedItem.Value != "Auswahl")
{
XDocument myDocument = XDocument.Load(MapPath("XMLTest.xml"));
var myQuery = from strResult in myDocument.Descendants("Logic").Descendants("Parent").Descendants("Child").Descendants("Child") where strResult.Attribute("ID").Value == Ebene3.SelectedItem.Value select strResult.Value;
foreach (var Item in myQuery)
{
MyLit.Text = Item;
}
}
}

XML Datei

<?xml version="1.0" encoding="utf-8" ?>
<Logic>
<Parent ID="ParentItem">
<Child ID="Child1.1">
<Child ID="Child1.1.1">TextBlock 1.1.1</Child>
<Child ID="Child1.1.2">TextBlock 1.1.2</Child>
<Child ID="Child1.1.3">TextBlock 1.1.3</Child>
<Child ID="Child1.1.4">TextBlock 1.1.4</Child>
<Child ID="Child1.1.5">TextBlock 1.1.5</Child>
</Child>
<Child ID="Child1.2">
<Child ID="Child1.2.1">TextBlock 1.2.1</Child>
<Child ID="Child1.2.2">TextBlock 1.2.2</Child>
<Child ID="Child1.2.3">TextBlock 1.2.3</Child>
<Child ID="Child1.2.4">TextBlock 1.2.4</Child>
<Child ID="Child1.2.5">TextBlock 1.2.5</Child>
</Child>
<Child ID="Child1.3">
<Child ID="Child1.3.1">TextBlock 1.3.1</Child>
<Child ID="Child1.3.2">TextBlock 1.3.2</Child>
<Child ID="Child1.3.3">TextBlock 1.3.3</Child>
<Child ID="Child1.3.4">TextBlock 1.3.4</Child>
<Child ID="Child1.3.5">TextBlock 1.3.5</Child>
</Child>
</Parent>
<Parent ID="ParentItem2">
<Child ID="Child2.1">
<Child ID="Child2.1.1">TextBlock 2.1.1</Child>
<Child ID="Child2.1.2">TextBlock 2.1.2</Child>
<Child ID="Child2.1.3">TextBlock 2.1.3</Child>
<Child ID="Child2.1.4">TextBlock 2.1.4</Child>
<Child ID="Child2.1.5">TextBlock 2.1.5</Child>
</Child>
<Child ID="Child2.2">
<Child ID="Child2.2.1">TextBlock 2.2.1</Child>
<Child ID="Child2.2.2">TextBlock 2.2.2</Child>
<Child ID="Child2.2.3">TextBlock 2.2.3</Child>
<Child ID="Child2.2.4">TextBlock 2.2.4</Child>
<Child ID="Child2.2.5">TextBlock 2.2.5</Child>
</Child>
</Parent>
<Parent ID="ParentItem3">
<Child ID="Child3.1">
<Child ID="Child3.1.1">TextBlock 3.1.1</Child>
<Child ID="Child3.1.2">TextBlock 3.1.2</Child>
<Child ID="Child3.1.3">TextBlock 3.1.3</Child>
<Child ID="Child3.1.4">TextBlock 3.1.4</Child>
<Child ID="Child3.1.5">TextBlock 3.1.5</Child>
</Child>
<Child ID="Child3.2">
<Child ID="Child3.2.1">TextBlock 3.2.1</Child>
<Child ID="Child3.2.2">TextBlock 3.2.2</Child>
<Child ID="Child3.2.3">TextBlock 3.2.3</Child>
<Child ID="Child3.2.4">TextBlock 3.2.4</Child>
<Child ID="Child3.2.5">TextBlock 3.2.5</Child>
</Child>
<Child ID="Child3.3">
<Child ID="Child3.3.1">TextBlock 3.3.1</Child>
<Child ID="Child3.3.2">TextBlock 3.3.2</Child>
<Child ID="Child3.3.3">TextBlock 3.3.3</Child>
<Child ID="Child3.3.4">TextBlock 3.3.4</Child>
<Child ID="Child3.3.5">TextBlock 3.3.5</Child>
</Child>
<Child ID="Child3.4">
<Child ID="Child3.4.1">TextBlock 3.4.1</Child>
<Child ID="Child3.4.2">TextBlock 3.4.2</Child>
<Child ID="Child3.4.3">TextBlock 3.4.3</Child>
<Child ID="Child3.4.4">TextBlock 3.4.4</Child>
<Child ID="Child3.4.5">TextBlock 3.4.5</Child>
</Child>
</Parent>
<Parent ID="ParentItem4">
<Child ID="Child4.1">
<Child ID="Child4.1.1">TextBlock 4.1.1</Child>
<Child ID="Child4.1.2">TextBlock 4.1.2</Child>
<Child ID="Child4.1.3">TextBlock 4.1.3</Child>
<Child ID="Child4.1.4">TextBlock 4.1.4</Child>
<Child ID="Child4.1.5">TextBlock 4.1.5</Child>
</Child>
<Child ID="Child4.2">
<Child ID="Child4.2.1">TextBlock 4.2.1</Child>
<Child ID="Child4.2.2">TextBlock 4.2.2</Child>
<Child ID="Child4.2.3">TextBlock 4.2.3</Child>
<Child ID="Child4.2.4">TextBlock 4.2.4</Child>
<Child ID="Child4.2.5">TextBlock 4.2.5</Child>
</Child>
</Parent>
</Logic>