How to pass parameters or arguments into a gradle task

Question

I have a gradle build script into which I am trying to include Eric Wendelin s css plugin - http   eriwen github io gradle-css-plugin   Its easy enough to implement  and because I only want minification  rather than combining and gzipping   I ve got the pertinent parts of the build script looking like this   minifyCss       source    src main webapp css brandA styles css      dest      buildDir  brandA styles css      yuicompressor           lineBreakPos   -1          war       baseName    ex-ren     war doFirst       tasks myTask minifyCss execute       This is perfect - when I run the gradle war task  it calls the minifyCss task  takes the source css file  and creates a minified version in the buildDir  However  I have a handful of css files which need minify-ing  but not combining into one file  hence I m not using the combineCss task   What I d like to be able to do is make the source and dest properties  assuming that s the correct terminology   of the minifyCss task reference variables of some sort - either variables passed into the task in the signature  or global variables  or something      Something like this I guess  which doesn t work    minifyCss sourceFile  destFile        source   sourceFile     dest   destFile     yuicompressor           lineBreakPos   -1          war       baseName    ex-ren     war doFirst       tasks myTask minifyCss execute  src main webapp css brandA styles css      buildDir  brandA styles css       tasks myTask minifyCss execute  src main webapp css brandB styles css      buildDir  brandB styles css       tasks myTask minifyCss execute  src main webapp css brandC styles css      buildDir  brandC styles css       This doesn t work either   def sourceFile   null def destFile   null  minifyCss       source   sourceFile     dest   destFile     yuicompressor           lineBreakPos   -1          war       baseName    ex-ren     war doFirst       sourceFile    src main webapp css brandA styles css      destFile      buildDir  brandA styles css      tasks myTask minifyCss execute       For the life of me I cannot work out how to call a task and pass variables in     Any help very much appreciated

User · Answer

I would suggest the method presented on the Gradle forum:

def createMinifyCssTask(def brand, def sourceFile, def destFile) {
    return tasks.create("minify${brand}Css", com.eriwen.gradle.css.tasks.MinifyCssTask) {
        source = sourceFile
        dest = destFile
    }
}

I have used this method myself to create custom tasks, and it works very well.

User · Answer

If the task you want to pass parameters to is of type JavaExec and you are using Gradle 5  for example the application plugin s run task  then you can pass your parameters through the --args     command line option  For example gradle run --args  foo --bar true     Otherwise there is no convenient builtin way to do this  but there are 3 workarounds   1  If few values  task creation function  If the possible values are few and are known in advance  you can programmatically create a task for each of them   void createTask String platform       String taskName    myTask     platform     task  taskName              do what you want         String   platforms     macosx    linux32    linux64    for String platform   platforms        createTask platform       You would then call your tasks the following way     gradlew myTask macosx   2  Standard input hack  A convenient hack is to pass the arguments through standard input  and have your task read from it     gradlew myTask  lt  lt  lt  arg1 arg2 arg  in  several  parts    with code below   String   splitIntoTokens String commandLine        String regex                 2                   s               S         Matcher matcher   Pattern compile regex  matcher commandLine       ArrayList lt String gt  result   new ArrayList lt  gt         while  matcher find              result add matcher group               return result toArray          task taskName            doFirst               String typed   new Scanner System in  nextLine                String   parsed   splitIntoTokens typed               println   Arguments received      parsed join                       do what you want                 You will also need to add the following lines at the top of your build script   import java util regex Matcher  import java util regex Pattern  import java util Scanner    3  -P parameters  The last option is to pass a -P parameter to Gradle     gradlew myTask -PmyArg hello   You can then access it as myArg in your build script   task myTask       doFirst          println myArg            do what you want           Credit to  789 for his answer on splitting arguments into tokens

User · Answer

You should consider passing the -P argument in invoking Gradle    From Gradle Documentation        --project-prop   Sets a project property of the root project  for example -Pmyprop myvalue  See Section 14 2     Gradle properties and system properties       Considering this build gradle   task printProp  lt  lt        println customProp     Invoking Gradle -PcustomProp myProp will give this output      gradle -PcustomProp myProp printProp  printProp myProp  BUILD SUCCESSFUL  Total time  3 722 secs   This is the way I found to pass parameters

User · Answer

Its nothing more easy  run command    gradlew clean -PjobId 9999 and in gradle use  println project gradle startParameter projectProperties  You will get clue

User · Answer

task mathOnProperties  lt  lt        println Integer parseInt a  Integer parseInt b      println new Integer a    new Integer b          gradle -Pa 3 -Pb 4 mathOnProperties  mathOnProperties 7 12  BUILD SUCCESSFUL

User · Answer

I think you probably want to view the minification of each set of css as a separate task  task minifyBrandACss type  com eriwen gradle css tasks MinifyCssTask         source    src main webapp css brandA styles css       dest      buildDir  brandA styles css     etc etc   BTW executing your minify tasks in an action of the war task seems odd to me - wouldn t it make more sense to make them a dependency of the war task

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