How do I make a section required for a sectiongroup in NSIS? - nsis

Question

I want to make a section inside of a sectiongroup required for that section group but not required for the entire install if the group is unchecked. I've tried "SectionIn R0" but this makes that section required for the entire install and I only want it to be required if they select the group itself.
SectionGroup "group"
Section "required for section group"
SectionIn RO
SectionEnd
Section "optional"
SectionEnd
SectionGroupEnd

Answer 1

You can't do this with just properties, you need some actual code:
!include Sections.nsh
!include LogicLib.nsh
SectionGroup /e "group"
Section "required for section group" SEC_REQ
SectionIn RO
SectionEnd
Section "optional" SEC_OPT
SectionEnd
SectionGroupEnd
Function .onSelChange
${If} ${SectionIsSelected} ${SEC_OPT}
!define /math MYSECTIONFLAGS ${SF_SELECTED} | ${SF_RO}
!insertmacro SetSectionFlag ${SEC_REQ} ${MYSECTIONFLAGS}
!undef MYSECTIONFLAGS
${Else}
!insertmacro ClearSectionFlag ${SEC_REQ} ${SF_RO}
${EndIf}
FunctionEnd
Note that there is a "bug" when unchecking the section group itself, to workaround that, you need to keep some global state since nsis does not tell you which section generated the notification. The following code has better logic:
!include Sections.nsh
!include LogicLib.nsh
SectionGroup /e "group" SEC_GRP
Section "required for section group" SEC_REQ
SectionIn RO
SectionEnd
Section "optional" SEC_OPT
SectionEnd
Section "" PRIVSEC_TOGGLESTATE ;hidden section to keep track of state
SectionEnd
SectionGroupEnd
Function .onSelChange
!define /math SECFLAGS_SELRO ${SF_SELECTED} | ${SF_RO}
${IfNot} ${SectionIsSelected} ${PRIVSEC_TOGGLESTATE}
${AndIf} ${SectionIsReadOnly} ${SEC_REQ}
!insertmacro ClearSectionFlag ${SEC_REQ} ${SECFLAGS_SELRO}
${EndIf}
${If} ${SectionIsSelected} ${SEC_OPT}
!insertmacro SetSectionFlag ${SEC_REQ} ${SECFLAGS_SELRO}
${Else}
!insertmacro ClearSectionFlag ${SEC_REQ} ${SF_RO}
${EndIf}
${If} ${SectionIsSelected} ${SEC_REQ}
!insertmacro SelectSection ${PRIVSEC_TOGGLESTATE}
${Else}
!insertmacro UnselectSection ${PRIVSEC_TOGGLESTATE}
${EndIf}
!undef SECFLAGS_SELRO
FunctionEnd

Answer 2

You can also set the sections as mandatory sections by using the SectionSetFlags command. You simply need to add it to the .onInit function as follows:
SectionGroup "group" Sec01
Section "required for section group"
SectionIn RO
SectionEnd
Section "optional" Sec02
SectionEnd
SectionGroupEnd
Function .onInit
SectionSetFlags ${Sec01} 17
FunctionEnd
This will gray "group" out, but it will be selected and installed as expected.

Answer 3

You can also setup a custom function which is being called when user clicks "Next" but no option is selected. In this function, you can check if any of Sections is selected or, as I did, check the variable which is set to "nothingSelected" on init, then modified when any section is created. If you put "Abort" in the custom function, the installer will stay on the same page. Here is a snippet:
page license
page directory
page components "" "" testSelection
page instfiles
function .onInit
StrCpy $somethingSelected "nothingSelected"
functionEnd
function testSelection
${If} $somethingSelected == "nothingSelected"
MessageBox MB_OK "Please select any option"
Abort
${EndIf}
functionEnd
function .onSelChange
#selecting mutually exclusive sections (removed for clarity)
StrCpy $somethingSelected $1
functionEnd