Fix broken support for nested validation with multiple errors (#321)

Fixes #319.

Signed-off-by: Johannes Löthberg <johannes.loethberg@elokon.com>

validator/src/types.rs

@@ -72,17 +72,16 @@ impl ValidationErrors {
     ) -> &mut ValidationErrors {
         match child {
             Ok(()) => self,
-            Err(errors) => {
-                for (_, e) in &errors.0 {
-                    if matches!(e, ValidationErrorsKind::Field(..)) {
-                        self.add_nested(
-                            field,
-                            ValidationErrorsKind::Struct(Box::new(errors.clone())),
-                        );
-                    } else {
-                        self.add_nested(field, e.clone());
-                    }
+            Err(mut errors) => {
+                // This is a bit of a hack to be able to support collections which return a
+                // `ValidationErrors` with a made-up `_tmp_validator` entry which we need to strip
+                // off.
+                if let Some(collection) = errors.0.remove("_tmp_validator") {
+                    self.add_nested(field, collection);
+                } else {
+                    self.add_nested(field, ValidationErrorsKind::Struct(Box::new(errors)));
                 }
+
                 self
             }
         }

validator_derive_tests/tests/nested.rs

@@ -39,6 +39,48 @@ fn is_fine_with_nested_validations() {
     assert!(root.validate().is_ok());
 }
 
+#[test]
+fn fails_nested_validation_multiple_members() {
+    #[derive(Validate)]
+    struct Root<'a> {
+        #[validate(length(min = 5, max = 10))]
+        value: String,
+        #[validate(nested)]
+        a: &'a A,
+    }
+
+    #[derive(Validate)]
+    struct A {
+        #[validate(length(min = 5, max = 10))]
+        value1: String,
+        #[validate(length(min = 5, max = 10))]
+        value2: String,
+    }
+
+    let root = Root {
+        value: "valid".to_string(),
+        a: &A { value1: "invalid value".to_string(), value2: "invalid value".to_string() },
+    };
+
+    let error_kind = ValidationErrorsKind::Field(vec![{
+        let mut error = ValidationError::new("length");
+        error.add_param("min".into(), &5);
+        error.add_param("max".into(), &10);
+        error.add_param("value".into(), &"invalid value");
+        error
+    }]);
+    assert_eq!(
+        root.validate(),
+        Err(ValidationErrors(HashMap::from_iter([(
+            "a",
+            ValidationErrorsKind::Struct(Box::new(ValidationErrors(HashMap::from_iter([
+                ("value1", error_kind.clone()),
+                ("value2", error_kind),
+            ]))))
+        )])))
+    );
+}
+
 #[test]
 fn fails_nested_validation() {
     #[derive(Validate)]