Allow explicitly specifying the backs to create migrations for

butane_cli/src/lib.rs

@@ -59,6 +59,29 @@ pub fn default_name() -> String {
     Utc::now().format("%Y%m%d_%H%M%S%3f").to_string()
 }
 
+/// Parse comma-separated backend names and validate they exist.
+pub fn parse_backends(backends_str: &str) -> Result<NonEmpty<Box<dyn Backend>>> {
+    let backend_names: Vec<&str> = backends_str
+        .split(',')
+        .map(|s| s.trim())
+        .filter(|s| !s.is_empty())
+        .collect();
+
+    if backend_names.is_empty() {
+        return Err(anyhow::anyhow!("No backends specified"));
+    }
+
+    let mut backends: Vec<Box<dyn Backend>> = Vec::new();
+
+    for name in backend_names {
+        let backend =
+            db::get_backend(name).ok_or_else(|| anyhow::anyhow!("Unknown backend: {}", name))?;
+        backends.push(backend);
+    }
+
+    Ok(NonEmpty::from_vec(backends).unwrap())
+}
+
 pub fn init(base_dir: &PathBuf, name: &str, connstr: &str, connect: bool) -> Result<()> {
     if db::get_backend(name).is_none() {
         eprintln!("Unknown backend {name}");
@@ -76,8 +99,13 @@ pub fn init(base_dir: &PathBuf, name: &str, connstr: &str, connect: bool) -> Res
 }
 
 /// Make a migration.
-/// The backends are selected from the existing migrations, or the initialised connection.
-pub fn make_migration(base_dir: &Path, name: Option<&String>) -> Result<()> {
+///
+/// The backends are selected from the CLI arg, existing migrations, or the initialised connection.
+pub fn make_migration(
+    base_dir: &Path,
+    name: Option<&String>,
+    cli_backends: Option<NonEmpty<Box<dyn Backend>>>,
+) -> Result<()> {
     let name = match name {
         Some(name) => format!("{}_{}", default_name(), name),
         None => default_name(),
@@ -87,7 +115,10 @@ pub fn make_migration(base_dir: &Path, name: Option<&String>) -> Result<()> {
         eprintln!("Migration {name} already exists");
         std::process::exit(1);
     }
-    let backends = load_backends(base_dir)?;
+    let backends = match cli_backends {
+        Some(backends) => backends,
+        None => load_backends(base_dir)?,
+    };
 
     let created = ms.create_migration(&backends, &name, ms.latest().as_ref())?;
     if created {

butane_cli/src/main.rs

@@ -6,8 +6,8 @@ use std::path::PathBuf;
 use butane_cli::{
     add_backend, base_dir, clean, clear_data, collapse_migrations, delete_table,
     describe_migration, detach_latest_migration, embed, get_migrations, handle_error, init,
-    list_backends, list_migrations, make_migration, migrate, regenerate_migrations, remove_backend,
-    unmigrate,
+    list_backends, list_migrations, make_migration, migrate, parse_backends, regenerate_migrations,
+    remove_backend, unmigrate,
 };
 use clap::{ArgAction, Parser, Subcommand};
 
@@ -37,6 +37,9 @@ enum Commands {
     MakeMigration {
         /// Name to use for the migration.
         name: String,
+        /// Comma-separated list of backends to use (e.g., "sqlite,pg")
+        #[arg(short = 'b', long)]
+        backends: Option<String>,
     },
     /// Detach the latest migration.
     #[command(
@@ -173,7 +176,19 @@ fn main() {
             BackendCommands::Remove { name } => handle_error(remove_backend(&base_dir, name)),
             BackendCommands::List => handle_error(list_backends(&base_dir)),
         },
-        Commands::MakeMigration { name } => handle_error(make_migration(&base_dir, Some(name))),
+        Commands::MakeMigration { name, backends } => {
+            let parsed_backends = match backends {
+                Some(backends_str) => match parse_backends(backends_str) {
+                    Ok(backends) => Some(backends),
+                    Err(e) => {
+                        handle_error(Err(e));
+                        return;
+                    }
+                },
+                None => None,
+            };
+            handle_error(make_migration(&base_dir, Some(name), parsed_backends))
+        }
         Commands::DescribeMigration { name } => handle_error(describe_migration(&base_dir, name)),
         Commands::Regenerate => handle_error(regenerate_migrations(&base_dir)),
         Commands::DetachMigration => handle_error(detach_latest_migration(&base_dir)),