RUST-507 Deserialize unsigned integers (#221)

Author: isabelatkinson

src/de/serde.rs

@@ -1,4 +1,4 @@
-use std::{fmt, vec};
+use std::{convert::TryFrom, fmt, vec};
 
 use serde::de::{
     self,
@@ -101,10 +101,7 @@ impl<'de> Visitor<'de> for BsonVisitor {
     where
         E: Error,
     {
-        Err(Error::invalid_type(
-            Unexpected::Unsigned(value as u64),
-            &"a signed integer",
-        ))
+        convert_unsigned_to_signed(value as u64)
     }
 
     #[inline]
@@ -120,10 +117,7 @@ impl<'de> Visitor<'de> for BsonVisitor {
     where
         E: Error,
     {
-        Err(Error::invalid_type(
-            Unexpected::Unsigned(value as u64),
-            &"a signed integer",
-        ))
+        convert_unsigned_to_signed(value as u64)
     }
 
     #[inline]
@@ -139,10 +133,7 @@ impl<'de> Visitor<'de> for BsonVisitor {
     where
         E: Error,
     {
-        Err(Error::invalid_type(
-            Unexpected::Unsigned(value as u64),
-            &"a signed integer",
-        ))
+        convert_unsigned_to_signed(value as u64)
     }
 
     #[inline]
@@ -158,10 +149,7 @@ impl<'de> Visitor<'de> for BsonVisitor {
     where
         E: Error,
     {
-        Err(Error::invalid_type(
-            Unexpected::Unsigned(value),
-            &"a signed integer",
-        ))
+        convert_unsigned_to_signed(value)
     }
 
     #[inline]
@@ -235,6 +223,22 @@ impl<'de> Visitor<'de> for BsonVisitor {
     }
 }
 
+fn convert_unsigned_to_signed<E>(value: u64) -> Result<Bson, E>
+where
+    E: Error,
+{
+    if let Ok(int32) = i32::try_from(value) {
+        Ok(Bson::Int32(int32))
+    } else if let Ok(int64) = i64::try_from(value) {
+        Ok(Bson::Int64(int64))
+    } else {
+        Err(Error::custom(format!(
+            "cannot represent {} as a signed number",
+            value
+        )))
+    }
+}
+
 /// Serde Deserializer
 pub struct Deserializer {
     value: Option<Bson>,

src/tests/serde.rs

@@ -12,6 +12,7 @@ use crate::{
     Binary,
     Bson,
     Deserializer,
+    Document,
     Serializer,
 };
 use serde::{Deserialize, Serialize};
@@ -573,3 +574,23 @@ fn test_de_oid_string() {
     let oid = ObjectId::with_string("507f1f77bcf86cd799439011").unwrap();
     assert_eq!(foo.oid, oid);
 }
+
+#[test]
+fn test_serialize_deserialize_unsigned_numbers() {
+    let _guard = LOCK.run_concurrently();
+
+    let num = 1;
+    let json = format!("{{ \"num\": {} }}", num);
+    let doc: Document = serde_json::from_str(&json).unwrap();
+    assert_eq!(doc.get_i32("num").unwrap(), num);
+
+    let num = i32::MAX as u64 + 1;
+    let json = format!("{{ \"num\": {} }}", num);
+    let doc: Document = serde_json::from_str(&json).unwrap();
+    assert_eq!(doc.get_i64("num").unwrap(), num as i64);
+
+    let num = u64::MAX;
+    let json = format!("{{ \"num\": {} }}", num);
+    let doc_result: Result<Document, serde_json::Error> = serde_json::from_str(&json);
+    assert!(doc_result.is_err());
+}