Set "default" on generated schemas (#6)

schemars/tests/default.rs

@@ -31,7 +31,6 @@ pub struct MyStruct2 {
 }
 
 #[test]
-#[ignore] // not yet implemented (https://github.com/GREsau/schemars/issues/6)
 fn schema_default_values() -> TestResult {
     test_default_generated_schema::<MyStruct>("default")
 }

schemars/tests/expected/schema-openapi3.json

@@ -72,6 +72,7 @@
     },
     "definitions": {
       "description": "The `$defs` keyword.\n\nThis is currently serialized as `definitions` for backwards compatibility.\n\nSee [JSON Schema 8.2.5. Schema Re-Use With \"$defs\"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-8.2.5).",
+      "default": {},
       "type": "object",
       "additionalProperties": {
         "$ref": "#/components/schemas/Schema"
@@ -79,6 +80,7 @@
     },
     "deprecated": {
       "description": "The `deprecated` keyword.\n\nSee [JSON Schema Validation 9.3. \"deprecated\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.3).",
+      "default": false,
       "type": "boolean"
     },
     "description": {
@@ -220,6 +222,7 @@
     },
     "patternProperties": {
       "description": "The `patternProperties` keyword.\n\nSee [JSON Schema 9.3.2.2. \"patternProperties\"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.2).",
+      "default": {},
       "type": "object",
       "additionalProperties": {
         "$ref": "#/components/schemas/Schema"
@@ -227,6 +230,7 @@
     },
     "properties": {
       "description": "The `properties` keyword.\n\nSee [JSON Schema 9.3.2.1. \"properties\"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.1).",
+      "default": {},
       "type": "object",
       "additionalProperties": {
         "$ref": "#/components/schemas/Schema"
@@ -243,10 +247,12 @@
     },
     "readOnly": {
       "description": "The `readOnly` keyword.\n\nSee [JSON Schema Validation 9.4. \"readOnly\" and \"writeOnly\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.4).",
+      "default": false,
       "type": "boolean"
     },
     "required": {
       "description": "The `required` keyword.\n\nSee [JSON Schema Validation 6.5.3. \"required\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.5.3).",
+      "default": [],
       "type": "array",
       "items": {
         "type": "string"
@@ -282,6 +288,7 @@
     },
     "writeOnly": {
       "description": "The `writeOnly` keyword.\n\nSee [JSON Schema Validation 9.4. \"readOnly\" and \"writeOnly\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.4).",
+      "default": false,
       "type": "boolean"
     }
   },
@@ -383,6 +390,7 @@
         },
         "deprecated": {
           "description": "The `deprecated` keyword.\n\nSee [JSON Schema Validation 9.3. \"deprecated\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.3).",
+          "default": false,
           "type": "boolean"
         },
         "description": {
@@ -524,6 +532,7 @@
         },
         "patternProperties": {
           "description": "The `patternProperties` keyword.\n\nSee [JSON Schema 9.3.2.2. \"patternProperties\"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.2).",
+          "default": {},
           "type": "object",
           "additionalProperties": {
             "$ref": "#/components/schemas/Schema"
@@ -531,6 +540,7 @@
         },
         "properties": {
           "description": "The `properties` keyword.\n\nSee [JSON Schema 9.3.2.1. \"properties\"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.1).",
+          "default": {},
           "type": "object",
           "additionalProperties": {
             "$ref": "#/components/schemas/Schema"
@@ -547,10 +557,12 @@
         },
         "readOnly": {
           "description": "The `readOnly` keyword.\n\nSee [JSON Schema Validation 9.4. \"readOnly\" and \"writeOnly\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.4).",
+          "default": false,
           "type": "boolean"
         },
         "required": {
           "description": "The `required` keyword.\n\nSee [JSON Schema Validation 6.5.3. \"required\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.5.3).",
+          "default": [],
           "type": "array",
           "items": {
             "type": "string"
@@ -586,6 +598,7 @@
         },
         "writeOnly": {
           "description": "The `writeOnly` keyword.\n\nSee [JSON Schema Validation 9.4. \"readOnly\" and \"writeOnly\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.4).",
+          "default": false,
           "type": "boolean"
         }
       },

schemars/tests/expected/schema.json

@@ -86,6 +86,7 @@
     },
     "definitions": {
       "description": "The `$defs` keyword.\n\nThis is currently serialized as `definitions` for backwards compatibility.\n\nSee [JSON Schema 8.2.5. Schema Re-Use With \"$defs\"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-8.2.5).",
+      "default": {},
       "type": "object",
       "additionalProperties": {
         "$ref": "#/definitions/Schema"
@@ -93,6 +94,7 @@
     },
     "deprecated": {
       "description": "The `deprecated` keyword.\n\nSee [JSON Schema Validation 9.3. \"deprecated\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.3).",
+      "default": false,
       "type": "boolean"
     },
     "description": {
@@ -274,6 +276,7 @@
     },
     "patternProperties": {
       "description": "The `patternProperties` keyword.\n\nSee [JSON Schema 9.3.2.2. \"patternProperties\"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.2).",
+      "default": {},
       "type": "object",
       "additionalProperties": {
         "$ref": "#/definitions/Schema"
@@ -281,6 +284,7 @@
     },
     "properties": {
       "description": "The `properties` keyword.\n\nSee [JSON Schema 9.3.2.1. \"properties\"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.1).",
+      "default": {},
       "type": "object",
       "additionalProperties": {
         "$ref": "#/definitions/Schema"
@@ -299,10 +303,12 @@
     },
     "readOnly": {
       "description": "The `readOnly` keyword.\n\nSee [JSON Schema Validation 9.4. \"readOnly\" and \"writeOnly\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.4).",
+      "default": false,
       "type": "boolean"
     },
     "required": {
       "description": "The `required` keyword.\n\nSee [JSON Schema Validation 6.5.3. \"required\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.5.3).",
+      "default": [],
       "type": "array",
       "items": {
         "type": "string"
@@ -346,6 +352,7 @@
     },
     "writeOnly": {
       "description": "The `writeOnly` keyword.\n\nSee [JSON Schema Validation 9.4. \"readOnly\" and \"writeOnly\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.4).",
+      "default": false,
       "type": "boolean"
     }
   },
@@ -459,6 +466,7 @@
         },
         "deprecated": {
           "description": "The `deprecated` keyword.\n\nSee [JSON Schema Validation 9.3. \"deprecated\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.3).",
+          "default": false,
           "type": "boolean"
         },
         "description": {
@@ -640,6 +648,7 @@
         },
         "patternProperties": {
           "description": "The `patternProperties` keyword.\n\nSee [JSON Schema 9.3.2.2. \"patternProperties\"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.2).",
+          "default": {},
           "type": "object",
           "additionalProperties": {
             "$ref": "#/definitions/Schema"
@@ -647,6 +656,7 @@
         },
         "properties": {
           "description": "The `properties` keyword.\n\nSee [JSON Schema 9.3.2.1. \"properties\"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.1).",
+          "default": {},
           "type": "object",
           "additionalProperties": {
             "$ref": "#/definitions/Schema"
@@ -665,10 +675,12 @@
         },
         "readOnly": {
           "description": "The `readOnly` keyword.\n\nSee [JSON Schema Validation 9.4. \"readOnly\" and \"writeOnly\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.4).",
+          "default": false,
           "type": "boolean"
         },
         "required": {
           "description": "The `required` keyword.\n\nSee [JSON Schema Validation 6.5.3. \"required\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.5.3).",
+          "default": [],
           "type": "array",
           "items": {
             "type": "string"
@@ -712,6 +724,7 @@
         },
         "writeOnly": {
           "description": "The `writeOnly` keyword.\n\nSee [JSON Schema Validation 9.4. \"readOnly\" and \"writeOnly\"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.4).",
+          "default": false,
           "type": "boolean"
         }
       },

schemars/tests/expected/skip_struct_fields.json

@@ -11,6 +11,7 @@
       "type": "null"
     },
     "readable": {
+      "default": "",
       "readOnly": true,
       "type": "string"
     },

schemars/tests/flatten.rs

@@ -38,6 +38,7 @@ struct Deep3 {
 
 #[derive(Debug, JsonSchema)]
 struct Deep4 {
+    #[serde(default)]
     os: &'static str,
 }
 

schemars_derive/src/lib.rs

@@ -281,11 +281,33 @@ fn schema_for_struct(fields: &[Field], cattrs: &attr::Container) -> TokenStream
         .filter(|f| !f.attrs.skip_deserializing() || !f.attrs.skip_serializing())
         .partition(|f| f.attrs.flatten());
 
-    let container_has_default = has_default(cattrs.default());
+    let set_container_default = match cattrs.default() {
+        SerdeDefault::None => None,
+        SerdeDefault::Default => Some(quote!(let cdefault = Self::default();)),
+        SerdeDefault::Path(path) => Some(quote!(let cdefault = #path();)),
+    };
+
     let mut required = Vec::new();
     let recurse = nested.iter().map(|field| {
         let name = field.attrs.name().deserialize_name();
-        if !container_has_default && !has_default(field.attrs.default()) {
+        let ty = field.ty;
+
+        // TODO respect serialize_with on field
+        let default = match field.attrs.default() {
+            SerdeDefault::None if set_container_default.is_some() => {
+                let field_ident = field
+                    .original
+                    .ident
+                    .as_ref()
+                    .expect("This is not a tuple struct, so field should be named");
+                Some(quote!(cdefault.#field_ident))
+            }
+            SerdeDefault::None => None,
+            SerdeDefault::Default => Some(quote!(<#ty>::default())),
+            SerdeDefault::Path(path) => Some(quote!(#path())),
+        };
+
+        if default.is_none() {
             required.push(name.clone());
         }
 
@@ -298,6 +320,7 @@ fn schema_for_struct(fields: &[Field], cattrs: &attr::Container) -> TokenStream
         let metadata = SchemaMetadata {
             read_only: field.attrs.skip_deserializing(),
             write_only: field.attrs.skip_serializing(),
+            default,
             ..get_metadata_from_docs(&field.original.attrs)
         };
         let schema_expr = set_metadata_on_schema(schema_expr, &metadata);
@@ -332,14 +355,10 @@ fn schema_for_struct(fields: &[Field], cattrs: &attr::Container) -> TokenStream
     });
 
     quote! {
+        {
+            #set_container_default
             #schema #(#flattens)*
         }
-}
-
-fn has_default(d: &SerdeDefault) -> bool {
-    match d {
-        SerdeDefault::None => false,
-        _ => true,
     }
 }
 

schemars_derive/src/metadata.rs

@@ -2,12 +2,13 @@ use crate::doc_attrs;
 use proc_macro2::TokenStream;
 use syn::Attribute;
 
-#[derive(Debug, Clone, PartialEq, Default)]
+#[derive(Debug, Clone, Default)]
 pub struct SchemaMetadata {
     pub title: Option<String>,
     pub description: Option<String>,
     pub read_only: bool,
     pub write_only: bool,
+    pub default: Option<TokenStream>,
 }
 
 pub fn set_metadata_on_schema_from_docs(
@@ -40,6 +41,7 @@ pub fn set_metadata_on_schema(schema_expr: TokenStream, metadata: &SchemaMetadat
             metadata.description = Some(#description.to_owned());
         })
     }
+
     if metadata.read_only {
         setters.push(quote! {
             metadata.read_only = true;
@@ -51,6 +53,15 @@ pub fn set_metadata_on_schema(schema_expr: TokenStream, metadata: &SchemaMetadat
         })
     }
 
+    if let Some(default) = &metadata.default {
+        setters.push(quote! {
+            metadata.default = match serde_json::json!(#default) {
+                serde_json::value::Value::Null => None,
+                d => Some(d),
+            };
+        })
+    }
+
     if setters.is_empty() {
         return schema_expr;
     }