How to use a CLI argument after subcommand with the structopt crate?

Question

For example, running my application with

./app --foo=bar get

works well, but

./app get --foo=bar

Produces an error:

error: Found argument '--foo' which wasn't expected, or isn't valid in this context

USAGE:
    app --foo <foo> get

Code:

use structopt::*;

#[derive(Debug, StructOpt)]
#[structopt(name = "app")]
struct CliArgs {
    #[structopt(long)]
    foo: String,
    #[structopt(subcommand)]
    cmd: Cmd,
}

#[derive(Debug, StructOpt)]
enum Cmd {
    Get,
    Set,
}

fn main() {
    let args = CliArgs::from_args();
    println!("{:?}", args);
}

Dependencies:

structopt = { version = "0.3", features = [ "paw" ] }
paw = "1.0"

NikBond · Accepted Answer · 2020-01-22T21:25:12.233

4

According to issue 237, there is a global parameter. Unexpectedly, it is not mentioned in the documentation.

With global = true it works well:

use structopt::*;

#[derive(Debug, StructOpt)]
#[structopt(name = "cli")]
struct CliArgs {
    #[structopt(
        long,
        global = true,
        default_value = "")]
    foo: String,
    #[structopt(subcommand)]
    cmd: Cmd,
}

#[derive(Debug, StructOpt)]
enum Cmd {
    Get,
    Set,
}

fn main() {
    let args = CliArgs::from_args();
    println!("{:?}", args);
}

Note that the global argument must be optional or have a default value.

edited Jan 22 '20 at 21:25

answered Jan 22 '20 at 21:19

NikBond

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1
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20

`global` is not mentioned in the documentation because it is a clap feature. But it is documented that `#[structopt(...)]` supports clap methods. – Carlos Marx Aug 21 '21 at 01:04

score 0 · Answer 2 · answered Jan 22 '20 at 21:19

You need to provide another struct for each command enum variant that has arguments:

use structopt::*; // 0.3.8

#[derive(Debug, StructOpt)]
struct CliArgs {
    #[structopt(subcommand)]
    cmd: Cmd,
}

#[derive(Debug, StructOpt)]
enum Cmd {
    Get(GetArgs),
    Set,
}

#[derive(Debug, StructOpt)]
struct GetArgs {
    #[structopt(long)]
    foo: String,
}

fn main() {
    let args = CliArgs::from_args();
    println!("{:?}", args);
}

./target/debug/example get --foo=1
CliArgs { cmd: Get(GetArgs { foo: "1" }) }

How to use a CLI argument after subcommand with the structopt crate?

2 Answers2