Fix validation of Literal from JSON keys when used as dict key (#1075)

Co-authored-by: David Montague <[email protected]>

Author: sydney-runkle

src/validators/literal.rs

@@ -9,7 +9,7 @@ use pyo3::{intern, PyTraverseError, PyVisit};
 
 use crate::build_tools::{py_schema_err, py_schema_error_type};
 use crate::errors::{ErrorType, ValError, ValResult};
-use crate::input::Input;
+use crate::input::{Input, ValidationMatch};
 use crate::py_gc::PyGcTraverse;
 use crate::tools::SchemaDict;
 
@@ -116,8 +116,18 @@ impl<T: Debug> LiteralLookup<T> {
             }
         }
         if let Some(expected_strings) = &self.expected_str {
-            // dbg!(expected_strings);
-            if let Ok(either_str) = input.exact_str() {
+            let validation_result = if input.is_python() {
+                input.exact_str()
+            } else {
+                // Strings coming from JSON are treated as "strict" but not "exact" for reasons
+                // of parsing types like UUID; see the implementation of `validate_str` for Json
+                // inputs for justification. We might change that eventually, but for now we need
+                // to work around this when loading from JSON
+                // V3 TODO: revisit making this "exact" for JSON inputs
+                input.validate_str(true, false).map(ValidationMatch::into_inner)
+            };
+
+            if let Ok(either_str) = validation_result {
                 let cow = either_str.as_cow()?;
                 if let Some(id) = expected_strings.get(cow.as_ref()) {
                     return Ok(Some((input, &self.values[*id])));

tests/test.rs

@@ -1,6 +1,6 @@
 #[cfg(test)]
 mod tests {
-    use _pydantic_core::SchemaSerializer;
+    use _pydantic_core::{SchemaSerializer, SchemaValidator};
     use pyo3::prelude::*;
     use pyo3::types::PyDict;
 
@@ -86,4 +86,35 @@ a = A()
             assert_eq!(serialized, b"{\"b\":\"b\"}");
         });
     }
+
+    #[test]
+    fn test_literal_schema() {
+        Python::with_gil(|py| {
+            let code = r#"
+schema = {
+    "type": "dict",
+    "keys_schema": {
+        "type": "literal",
+        "expected": ["a", "b"],
+    },
+    "values_schema": {
+        "type": "str",
+    },
+    "strict": False,
+}
+json_input = '{"a": "something"}'
+            "#;
+            let locals = PyDict::new(py);
+            py.run(code, None, Some(locals)).unwrap();
+            let schema: &PyDict = locals.get_item("schema").unwrap().unwrap().extract().unwrap();
+            let json_input: &PyAny = locals.get_item("json_input").unwrap().unwrap().extract().unwrap();
+            let binding = SchemaValidator::py_new(py, schema, None)
+                .unwrap()
+                .validate_json(py, json_input, None, None, None)
+                .unwrap();
+            let validation_result: &PyAny = binding.extract(py).unwrap();
+            let repr = format!("{}", validation_result.repr().unwrap());
+            assert_eq!(repr, "{'a': 'something'}");
+        });
+    }
 }