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Dynamic Installer Requirements - <dynamicinstallerrequirements>

Introduced in IzPack 5.0, the <dynamicinstallerrequirements>  element is used to enhance the "classic" installer requirement checking that IzPack does at the beginning of an installation process. This stops the installation unless a certain condition is met.

With the dynamicinstallerrequirements element, you can check a certain set of conditions on each panel change, using a panel data validator to check if the required conditions are met.

Code Block
titleCommon Example
languagehtml/xml
<dynamicinstallerrequirements>
  <installerrequirement severity="ERROR"
                        condition="this.condition.must.not.happen"
                        messageid="this.condition.must.not.happen.translation.id"/>
  <installerrequirement severity="ERROR"
                        condition="this.condition.may.happen"
                        messageid="this.condition.may.happen.translation.id"/>
  ...
</dynamicinstallerrequirements>

The installer requirement is actively checked on changing from each panel the DynamicInstallerRequirementValidator is assigned to.

If a condition applies, a messagebox is shown with the appropriate content from translation. Depending on the value of severity attribute the installation might be continued or is aborted:

  • "ERROR"
    The messagebox is shown and the installation aborts.
  • "WARNING"
    The messagebox is shown and the installation can continue after the OK button is pressed.

A more detailed example:

Code Block
languagehtml/xml
<condition type="variable" id="isNew">
  <name>previous.version</name>
  <value>XX.XX.XX</value>
</condition>
<condition type="not" id="isUpgrade">
  <condition type="ref" refid="isNew"/>
</condition>
...
<dynamicinstallerrequirements>
  <!-- The 'severity' attribute on this element violates the schema. A patch was 
       created and a pull request submitted at https://github.com/izpack/izpack/pull/140
       to change this attribute to 'status' in accordance with the schema. 
  
       'severity' works, but your IDE may tell you that the you're in violation
       of the schema if you have schema validation enabled. -->
  <installerrequirement condition="isUpgrade" severity="WARNING" messageid="not.an.upgrade.warning.message"/>
</dynamicinstallerrequirements>
...
<panels>
  <panel classname="HelloPanel"/>
  <panel classname="TargetPanel">
 
    <!-- This definition does not work in the latest development builds. Commenting out for now. -->
    <!-- <validator classname="DynamicInstallerRequirementValidator"/> -->
  </panel>
  <panel classname="PacksPanel"/>
  <panel classname="InstallPanel"/>
  <panel classname="FinishPanel"/>
</panels>

On each panel with a DynamicInstallerRequirementValidator assigned will be evaluated according to the requirements given as nested elements in <dynamicinstallerrequirements>.

<installerrequirement> - Attributes

AttributeDescriptionDefaultRequired
severity
Note

Please see the note in the code above about severity vs status.

The severity the validator should apply in case of the condition gets true.

Possible values: "WARNING" | "ERROR"

  •  "WARNING"
    Shows a warning message but does not abort.
  • "ERROR"
    Shows a message and aborts the installation.
noneyes
condition
A valid condition ID defined within the <conditions/> element.noneyes
messageid
A valid message ID from the appropriate translation file. If it can't be found the mentioned ID itself is displayed instead of the translated text.noneyes