Generate schema from any serializable value (#75)

Implement schema_for_value!(...) macro

schemars/tests/expected/from_value_2019_09.json

@@ -0,0 +1,80 @@
+{
+  "$schema": "https://json-schema.org/draft/2019-09/schema",
+  "title": "MyStruct",
+  "examples": [
+    {
+      "myBool": true,
+      "myInnerStruct": {
+        "my_empty_map": {},
+        "my_empty_vec": [],
+        "my_map": {
+          "": 0.0
+        },
+        "my_tuple": [
+          "💩",
+          42
+        ],
+        "my_vec": [
+          "hello",
+          "world"
+        ]
+      },
+      "myInt": 123,
+      "myNullableEnum": null
+    }
+  ],
+  "type": "object",
+  "properties": {
+    "myInt": {
+      "type": "integer",
+      "format": "int32"
+    },
+    "myBool": {
+      "type": "boolean"
+    },
+    "myNullableEnum": true,
+    "myInnerStruct": {
+      "type": "object",
+      "properties": {
+        "my_map": {
+          "type": "object",
+          "additionalProperties": {
+            "type": "number",
+            "format": "double"
+          }
+        },
+        "my_vec": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "my_empty_map": {
+          "type": "object",
+          "additionalProperties": true
+        },
+        "my_empty_vec": {
+          "type": "array",
+          "items": true
+        },
+        "my_tuple": {
+          "type": "array",
+          "items": [
+            {
+              "type": "string",
+              "maxLength": 1,
+              "minLength": 1
+            },
+            {
+              "type": "integer",
+              "format": "uint8",
+              "minimum": 0.0
+            }
+          ],
+          "maxItems": 2,
+          "minItems": 2
+        }
+      }
+    }
+  }
+}

schemars/tests/expected/from_value_draft07.json

@@ -0,0 +1,80 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "MyStruct",
+  "examples": [
+    {
+      "myBool": true,
+      "myInnerStruct": {
+        "my_empty_map": {},
+        "my_empty_vec": [],
+        "my_map": {
+          "": 0.0
+        },
+        "my_tuple": [
+          "💩",
+          42
+        ],
+        "my_vec": [
+          "hello",
+          "world"
+        ]
+      },
+      "myInt": 123,
+      "myNullableEnum": null
+    }
+  ],
+  "type": "object",
+  "properties": {
+    "myInt": {
+      "type": "integer",
+      "format": "int32"
+    },
+    "myBool": {
+      "type": "boolean"
+    },
+    "myNullableEnum": true,
+    "myInnerStruct": {
+      "type": "object",
+      "properties": {
+        "my_map": {
+          "type": "object",
+          "additionalProperties": {
+            "type": "number",
+            "format": "double"
+          }
+        },
+        "my_vec": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "my_empty_map": {
+          "type": "object",
+          "additionalProperties": true
+        },
+        "my_empty_vec": {
+          "type": "array",
+          "items": true
+        },
+        "my_tuple": {
+          "type": "array",
+          "items": [
+            {
+              "type": "string",
+              "maxLength": 1,
+              "minLength": 1
+            },
+            {
+              "type": "integer",
+              "format": "uint8",
+              "minimum": 0.0
+            }
+          ],
+          "maxItems": 2,
+          "minItems": 2
+        }
+      }
+    }
+  }
+}

schemars/tests/expected/from_value_openapi3.json

@@ -0,0 +1,80 @@
+{
+  "$schema": "https://spec.openapis.org/oas/3.0/schema/2019-04-02#/definitions/Schema",
+  "title": "MyStruct",
+  "type": "object",
+  "properties": {
+    "myInt": {
+      "type": "integer",
+      "format": "int32"
+    },
+    "myBool": {
+      "type": "boolean"
+    },
+    "myNullableEnum": {
+      "nullable": true
+    },
+    "myInnerStruct": {
+      "type": "object",
+      "properties": {
+        "my_map": {
+          "type": "object",
+          "additionalProperties": {
+            "type": "number",
+            "format": "double"
+          }
+        },
+        "my_vec": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "my_empty_map": {
+          "type": "object",
+          "additionalProperties": true
+        },
+        "my_empty_vec": {
+          "type": "array",
+          "items": {}
+        },
+        "my_tuple": {
+          "type": "array",
+          "items": [
+            {
+              "type": "string",
+              "maxLength": 1,
+              "minLength": 1
+            },
+            {
+              "type": "integer",
+              "format": "uint8",
+              "minimum": 0.0
+            }
+          ],
+          "maxItems": 2,
+          "minItems": 2
+        }
+      }
+    }
+  },
+  "example": {
+    "myBool": true,
+    "myInnerStruct": {
+      "my_empty_map": {},
+      "my_empty_vec": [],
+      "my_map": {
+        "": 0.0
+      },
+      "my_tuple": [
+        "💩",
+        42
+      ],
+      "my_vec": [
+        "hello",
+        "world"
+      ]
+    },
+    "myInt": 123,
+    "myNullableEnum": null
+  }
+}

schemars/tests/from_value.rs

@@ -0,0 +1,77 @@
+mod util;
+use std::collections::HashMap;
+
+use schemars::gen::SchemaSettings;
+use serde::Serialize;
+use util::*;
+
+#[derive(Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct MyStruct {
+    pub my_int: i32,
+    pub my_bool: bool,
+    pub my_nullable_enum: Option<MyEnum>,
+    pub my_inner_struct: MyInnerStruct,
+    #[serde(skip)]
+    pub skip: i32,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub skip_if_none: Option<MyEnum>,
+}
+
+#[derive(Serialize)]
+pub struct MyInnerStruct {
+    pub my_map: HashMap<String, f64>,
+    pub my_vec: Vec<&'static str>,
+    pub my_empty_map: HashMap<String, f64>,
+    pub my_empty_vec: Vec<&'static str>,
+    pub my_tuple: (char, u8),
+}
+
+#[derive(Serialize)]
+pub enum MyEnum {
+    StringNewType(String),
+    StructVariant { floats: Vec<f32> },
+}
+
+fn make_value() -> MyStruct {
+    let mut value = MyStruct {
+        my_int: 123,
+        my_bool: true,
+        my_nullable_enum: None,
+        my_inner_struct: MyInnerStruct {
+            my_map: HashMap::new(),
+            my_vec: vec!["hello", "world"],
+            my_empty_map: HashMap::new(),
+            my_empty_vec: vec![],
+            my_tuple: ('💩', 42),
+        },
+        skip: 123,
+        skip_if_none: None,
+    };
+    value.my_inner_struct.my_map.insert(String::new(), 0.0);
+    value
+}
+
+#[test]
+fn schema_from_value_matches_draft07() -> TestResult {
+    let gen = SchemaSettings::draft07().into_generator();
+    let actual = gen.into_root_schema_for_value(&make_value())?;
+
+    test_schema(&actual, "from_value_draft07")
+}
+
+#[test]
+fn schema_from_value_matches_2019_09() -> TestResult {
+    let gen = SchemaSettings::draft2019_09().into_generator();
+    let actual = gen.into_root_schema_for_value(&make_value())?;
+
+    test_schema(&actual, "from_value_2019_09")
+}
+
+#[test]
+fn schema_from_value_matches_openapi3() -> TestResult {
+    let gen = SchemaSettings::openapi3().into_generator();
+    let actual = gen.into_root_schema_for_value(&make_value())?;
+
+    test_schema(&actual, "from_value_openapi3")
+}

schemars/tests/ui/schema_for_arg_value.rs

@@ -0,0 +1,5 @@
+use schemars::schema_for;
+
+fn main() {
+    let _schema = schema_for!(123);
+}

schemars/tests/ui/schema_for_arg_value.stderr

@@ -0,0 +1,7 @@
+error: This argument to `schema_for!` is not a type - did you mean to use `schema_for_value!` instead?
+ --> $DIR/schema_for_arg_value.rs:4:19
+  |
+4 |     let _schema = schema_for!(123);
+  |                   ^^^^^^^^^^^^^^^^
+  |
+  = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

schemars/tests/util/mod.rs

@@ -18,7 +18,7 @@ pub fn test_default_generated_schema<T: JsonSchema>(file: &str) -> TestResult {
     test_schema(&actual, file)
 }
 
-fn test_schema(actual: &RootSchema, file: &str) -> TestResult {
+pub fn test_schema(actual: &RootSchema, file: &str) -> TestResult {
     let expected_json = match fs::read_to_string(format!("tests/expected/{}.json", file)) {
         Ok(j) => j,
         Err(e) => {