I would like to parse options with picocli in the following format:
application -mode CLIENT -c aaaa -d bbbb
application -mode SERVER -e xxxx -f yyyy
mode
is an enum
with values { CLIENT, SERVER }
mode == CLIENT
, -c
and -d
options are mandatory, and -e
, -f
must not be used.mode == SERVER
, -e
and -f
options are mandatory, and -c
, -d
must not be used.In other words, I would like to choose the required options based on a key option. Is this possible in picocli?
Yes, this is possible. One way is simple programmatic validation:
import picocli.CommandLine;
import picocli.CommandLine.Command;
import picocli.CommandLine.Model.CommandSpec;
import picocli.CommandLine.Option;
import picocli.CommandLine.ParameterException;
import picocli.CommandLine.Spec;
import java.util.Objects;
import java.util.function.Predicate;
@Command(name = "application", mixinStandardHelpOptions = true)
public class MyApp implements Runnable {
enum Mode {CLIENT, SERVER}
@Option(names = "-mode", required = true)
Mode mode;
@Option(names = "-c") String c;
@Option(names = "-d") String d;
@Option(names = "-e") String e;
@Option(names = "-f") String f;
@Spec CommandSpec spec;
public static void main(String[] args) {
System.exit(new CommandLine(new MyApp()).execute(args));
}
@Override
public void run() {
validateInput();
// business logic here...
}
private void validateInput() {
String INVALID = "Error: option(s) %s cannot be used in %s mode";
String REQUIRED = "Error: option(s) %s are required in %s mode";
if (mode == Mode.CLIENT) {
check(INVALID, "CLIENT", Objects::isNull, e, "-e", f, "-f");
check(REQUIRED, "CLIENT", Objects::nonNull, c, "-c", d, "-d");
} else if (mode == Mode.SERVER) {
check(INVALID, "SERVER", Objects::isNull, c, "-c", d, "-d");
check(REQUIRED, "SERVER", Objects::nonNull, e, "-e", f, "-f");
}
}
private void check(String msg, String param, Predicate<String> validator, String... valuesAndLabels) {
String desc = "";
String sep = "";
for (int i = 0; i < valuesAndLabels.length; i += 2) {
if (validator.test(valuesAndLabels[i])) {
desc = sep + valuesAndLabels[i + 1];
sep = ", ";
}
}
if (desc.length() > 0) {
throw new ParameterException(spec.commandLine(), String.format(msg, desc, param));
}
}
}
Alternatively, if you are willing to change your requirements a little bit, we can use picocli's argument groups for a more declarative approach:
import picocli.CommandLine;
import picocli.CommandLine.ArgGroup;
import picocli.CommandLine.Command;
import picocli.CommandLine.Option;
@Command(name = "application", mixinStandardHelpOptions = true)
public class MyApp2 implements Runnable {
static class ClientArgs {
@Option(names = "-clientMode", required = true) boolean clientMode;
@Option(names = "-c", required = true) String c;
@Option(names = "-d", required = true) String d;
}
static class ServerArgs {
@Option(names = "-serverMode", required = true) boolean serverMode;
@Option(names = "-e", required = true) String e;
@Option(names = "-f", required = true) String f;
}
static class Args {
@ArgGroup(exclusive = false, multiplicity = "1", heading = "CLIENT mode args%n")
ClientArgs clientArgs;
@ArgGroup(exclusive = false, multiplicity = "1", heading = "SERVER mode args%n")
ServerArgs serverArgs;
}
@ArgGroup(exclusive = true, multiplicity = "1")
Args args;
public static void main(String[] args) {
System.exit(new CommandLine(new MyApp2()).execute(args));
}
@Override
public void run() {
// business logic here...
}
}
When invoked with just -serverMode
, this second example will show this error message, followed by the usage help message:
Error: Missing required argument(s): -e=<e>, -f=<f>
Usage: application ((-clientMode -c=<c> -d=<d>) | (-serverMode -e=<e> -f=<f>))
...
Note that this declarative approach cannot be achieved with a single -mode
option: each argument group needs its own option (I chose -clientMode
and -serverMode
in this example). This allows the picocli parser to figure out which options must occur together and which are mutually exclusive.
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