The Conditions Element

This element allows you to define conditions which can be used to dynamically change the installer, e.g. the panels shown, the variables set, files parsed, files executed and much more. When you define a condition it will get a type and an id. The id has to be unique. Conditions can be referenced based on this id (e.g. with the RefCondition).

There are several built-in types of conditions. At the time of writing this, Izpack has the following built-in types:

There are also boolean types to combine more than one condition:

When you define a set of conditions, you just have to write as many <condition> tags as you like. A condition can take the following attributesWhen you define a set of conditions, you just have to write as many <condition> tags as you like.

Basic Condition Types

The following basic types of conditions can be used:

• Dynamic conditions
• Aggregate conditions
• Predefined conditions

See the links for more details.

Using Conditions

Defining Conditions

<conditions> Element

Conditions are defined in the installation definition as nested <condition> elements of the <conditions/> element.

For example: 

• Dynamic Installer Requirements
• ConditionDataValidator
• Panels

<condition> - Attributes

The following attributes must be set in a <condition> element definition:

<condition> - Nested Elements

The condition element can have several child elements depending on the condition type of this conditions. E.g. . For instance, the VariableCondition has a name and value child element to specify, which variable should have a certain value to fullfil this condition.

This Here is an example which defines four conditions, two VariableConditions, a JavaCondition and a AndCondition which will refer to two of the first conditions.:

<conditions>
<conditions>    <condition type="variable" id="standardinstallation">
        <name>setup.type</name>
        <value>standard</value>
    </condition>
    <condition type="variable" id="expertinstallation">
        <name>setup.type</name>
        <value>expert</value>
    </condition>
    <condition type="java" id="installonwindows">
        <java>
            <class>com.izforge.izpack.util.OsVersion</class>
            <field>IS_WINDOWS</field>
        </java>
        <returnvalue type="boolean">true</returnvalue>
    </condition>
    <condition type="and" id="standardinstallation.onwindows">
        <condition type="ref" refid="standardinstallation"/>
        <condition type="ref" refid="installonwindows" />
    </condition>
</conditions>

Expression languages

...

Anchor
Referencing Conditions Referencing Conditions

Referencing Conditions

Conditions are referenced as optional attributes of several other elements in a installation definition or from IzPack resources:

• as condition attribute
• as conditionid attribute (for compatibility reasons of some tags)

Referencing A Number Of Conditions In One Expression

Anchor
Simple Expression Language Simple Expression Language

Simple Expression Language

From IzPack 3.11 on, you don't have to define compound conditions because you can use a simple expression language. The language supports the following operators:

These simple expressions DO NOT follow the usual boolean logic with precedence rules. Instead, they are evaluated left to right in a simple way.

Example:

...

!conditionA+conditionB+!conditionC

...

does not equal

(!conditionA) && conditionB && (!conditionC)

...

but is the same like

!(conditionA && (conditionB && !(conditionC)))

Example:

<dynamicvariables>
    <variable name="db.

...

instance" value="MSSQLSERVER" checkonce="true" condition="useMssql+mssqlInstanceSelected+!haveDatabaseURL" />
</dynamicvariables>

Anchor
Complex expression language Complex expression language

Complex expression language

With IZPACK-577 fixed and released, you can also Beginning with IzPack 5.0, there is also the possibility to use a more Complex complex expression language that which evaluates using the based on boolean precedence rules, which is also reflected in the following table. The higher an operator is, the higher is its precedence.

Example:

@!conditionA

...

&&conditionB

...

&&!conditionC

equals

(!conditionA) && conditionB && (!conditionC)

...

XOR and parentheses () may be added in the future.

More types of conditions can be defined by inheriting com.izforge.izpack.Condition class.

Built-in conditions

A number of built-in condition IDs are available for you.

...

Name

...

Condition

...

izpack.windowsinstall

...

The OS is (any) Windows

...

izpack.windowsinstall.xp

...

The OS is Windows XP

...

izpack.windowsinstall.2003

...

The OS is Windows Server 2003

...

izpack.windowsinstall.vista

...

The OS is Windows Vista

...

izpack.windowsinstall.7

...

The OS is Windows 7

...

izpack.macinstall

...

The OS is Mac OS X

...

izpack.linuxinstall

...

The OS is a Linux variant

...

izpack.solarisinstall

...

The OS is a Solaris variant

...

izpack.solarisinstall.x86

...

The OS is a Solaris x86 variant

...

izpack.solarisinstall.sparc

...

In order to use the complex expression language the expression must start with a '@' character.

Example:

<dynamicvariables>
    <variable name="db.instance" value="MSSQLSERVER" checkonce="true" condition="@useMssql &amp;&amp; !haveDatabaseURL &amp;&amp; mssqlInstanceSelected" />
</dynamicvariables>