fix: long default values in optional field

Cargo.toml

@@ -6,7 +6,7 @@ members = [
 resolver = "2"
 
 [workspace.package]
-version = "0.16.0"
+version = "0.16.1"
 edition = "2021"
 authors = ["Antonio Yang <yanganto@gmail.com>", "faervan <faervan@proton.me>"]
 license = "MIT"

derive/src/lib.rs

@@ -568,7 +568,11 @@ impl Intermediate {
                     match field.default {
                         DefaultSource::DefaultValue(default) => {
                             field_example.push_str(" = ");
-                            field_example.push_str(&default);
+                            if field.optional {
+                                field_example.push_str(&default.replace('\n', "\n# "));
+                            } else {
+                                field_example.push_str(&default);
+                            }
                             field_example.push('\n');
                         }
                         DefaultSource::DefaultFn(None) => match struct_default {

flake.nix

@@ -1,7 +1,7 @@
 {
 
   inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.05";
     rust-overlay.url = "github:oxalica/rust-overlay";
     flake-utils.url = "github:numtide/flake-utils";
   };

lib/Cargo.toml

@@ -11,7 +11,7 @@ license.workspace = true
 readme.workspace = true
 
 [dependencies]
-toml-example-derive = { version = "=0.16.0", path = "../derive" }
+toml-example-derive = { version = "=0.16.1", path = "../derive" }
 
 [dev-dependencies]
 serde = { version = "1.0", features = ["derive"] }

lib/src/lib.rs

@@ -1279,6 +1279,45 @@ a = ""
 [instance.example]
 a = ""
 
+"#
+        );
+    }
+
+    #[test]
+    fn optional_long_vector_field() {
+        #[derive(TomlExample)]
+        #[allow(dead_code)]
+        struct Foo {
+            /// Option<Vec<String>>, with small default values
+            #[toml_example(default = ["a", "b", "c"])]
+            array_value_example: Option<Vec<String>>,
+
+            /// Option<Vec<String>>, with long default values
+            #[toml_example(default = ["aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+                "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb", 
+                "ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc", 
+                "ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd"
+            ])]
+            array_long_value_example: Option<Vec<String>>,
+
+            /// Option<Vec<String>>, with a long default value but no space after comma
+            #[toml_example(default = ["aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb","ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc","ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd"])]
+            array_long_value_no_space_example: Option<Vec<String>>,
+        }
+        assert_eq!(
+            Foo::toml_example(),
+            r#"# Option<Vec<String>>, with small default values
+# array_value_example = ["a", "b", "c"]
+
+# Option<Vec<String>>, with long default values
+# array_long_value_example = ["aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+# "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
+# "ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc",
+# "ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd"]
+
+# Option<Vec<String>>, with a long default value but no space after comma
+# array_long_value_no_space_example = ["aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb","ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc","ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd"]
+
 "#
         );
     }