From 18c2d417e359a71bed7e0f61cf4d062134c284d4 Mon Sep 17 00:00:00 2001
From: Graham Esau <gesau@hotmail.co.uk>
Date: Sat, 19 Oct 2019 21:03:34 +0100
Subject: [PATCH] Fix schema generation for flatten Options

---
 schemars/src/json_schema_impls/core.rs  | 12 +++++++++--
 schemars/src/json_schema_impls/deref.rs |  4 ++++
 schemars/src/lib.rs                     |  2 +-
 schemars/tests/flatten.rs               | 27 ++++++++++++++++---------
 schemars_derive/src/lib.rs              |  2 +-
 5 files changed, 34 insertions(+), 13 deletions(-)

diff --git a/schemars/src/json_schema_impls/core.rs b/schemars/src/json_schema_impls/core.rs
index 813a5d1..f0bf60c 100644
--- a/schemars/src/json_schema_impls/core.rs
+++ b/schemars/src/json_schema_impls/core.rs
@@ -46,8 +46,16 @@ impl<T: JsonSchema> JsonSchema for Option<T> {
         schema
     }
 
-    fn json_schema_non_null(gen: &mut SchemaGenerator) -> Schema {
-        T::json_schema_non_null(gen)
+    fn json_schema_optional(gen: &mut SchemaGenerator) -> Schema {
+        let mut schema = T::json_schema_optional(gen);
+        if let Schema::Object(SchemaObject {
+            object: Some(ref mut object_validation),
+            ..
+        }) = schema
+        {
+            object_validation.required.clear();
+        }
+        schema
     }
 }
 
diff --git a/schemars/src/json_schema_impls/deref.rs b/schemars/src/json_schema_impls/deref.rs
index 853988e..d836090 100644
--- a/schemars/src/json_schema_impls/deref.rs
+++ b/schemars/src/json_schema_impls/deref.rs
@@ -19,6 +19,10 @@ macro_rules! deref_impl {
             fn json_schema(gen: &mut SchemaGenerator) -> Schema {
                 T::json_schema(gen)
             }
+
+            fn json_schema_optional(gen: &mut SchemaGenerator) -> Schema {
+                T::json_schema_optional(gen)
+            }
         }
     };
 }
diff --git a/schemars/src/lib.rs b/schemars/src/lib.rs
index 20daaf7..2f3fe61 100644
--- a/schemars/src/lib.rs
+++ b/schemars/src/lib.rs
@@ -27,7 +27,7 @@ pub trait JsonSchema {
     fn json_schema(gen: &mut gen::SchemaGenerator) -> Schema;
 
     #[doc(hidden)]
-    fn json_schema_non_null(gen: &mut gen::SchemaGenerator) -> Schema {
+    fn json_schema_optional(gen: &mut gen::SchemaGenerator) -> Schema {
         Self::json_schema(gen)
     }
 }
diff --git a/schemars/tests/flatten.rs b/schemars/tests/flatten.rs
index 04224e3..a191666 100644
--- a/schemars/tests/flatten.rs
+++ b/schemars/tests/flatten.rs
@@ -4,31 +4,40 @@ use schemars::{schema_for, JsonSchema};
 
 #[derive(Debug, JsonSchema)]
 struct Flat {
-    foo: f32,
-    bar: bool,
-    baz: String,
-    foobar: Vec<i32>,
+    f: f32,
+    b: bool,
+    s: String,
+    #[serde(default)]
+    os: String,
+    v: Vec<i32>,
 }
 
 #[derive(Debug, JsonSchema)]
 #[schemars(rename = "Flat")]
 struct Deep1 {
-    foo: f32,
-    #[serde(flatten)]
+    f: f32,
+    #[schemars(flatten)]
     deep2: Deep2,
-    foobar: Vec<i32>,
+    v: Vec<i32>,
 }
 
 #[derive(Debug, JsonSchema)]
 struct Deep2 {
-    bar: bool,
+    b: bool,
     #[serde(flatten)]
     deep3: Deep3,
+    #[serde(flatten)]
+    deep4: Box<Option<Option<Box<Deep4>>>>,
 }
 
 #[derive(Debug, JsonSchema)]
 struct Deep3 {
-    baz: &'static str,
+    s: &'static str,
+}
+
+#[derive(Debug, JsonSchema)]
+struct Deep4 {
+    os: &'static str,
 }
 
 #[test]
diff --git a/schemars_derive/src/lib.rs b/schemars_derive/src/lib.rs
index 6a4453c..7aaee6e 100644
--- a/schemars_derive/src/lib.rs
+++ b/schemars_derive/src/lib.rs
@@ -318,7 +318,7 @@ fn schema_for_struct(fields: &[Field], cattrs: &attr::Container) -> TokenStream
     let flattens = flat.iter().map(|field| {
         let ty = get_json_schema_type(field);
         quote_spanned! {field.original.span()=>
-            .flatten(<#ty>::json_schema_non_null(gen))
+            .flatten(<#ty>::json_schema_optional(gen))
         }
     });