RUST-868 Add serialize_object_id_as_hex_string helper (#273)

Author: isabelatkinson

src/serde_helpers.rs

@@ -2,7 +2,9 @@
 
 use std::{convert::TryFrom, result::Result};
 
-use serde::{ser, Serializer};
+use serde::{ser, Serialize, Serializer};
+
+use crate::oid::ObjectId;
 
 pub use bson_datetime_as_rfc3339_string::{
     deserialize as deserialize_bson_datetime_from_rfc3339_string,
@@ -82,6 +84,14 @@ pub fn serialize_u64_as_i64<S: Serializer>(val: &u64, serializer: S) -> Result<S
     }
 }
 
+/// Serializes an [`ObjectId`] as a hex string.
+pub fn serialize_object_id_as_hex_string<S: Serializer>(
+    val: &ObjectId,
+    serializer: S,
+) -> Result<S::Ok, S::Error> {
+    val.to_hex().serialize(serializer)
+}
+
 /// Contains functions to serialize a u32 as an f64 (BSON double) and deserialize a
 /// u32 from an f64 (BSON double).
 ///

src/tests/serde.rs

@@ -11,6 +11,7 @@ use crate::{
         bson_datetime_as_rfc3339_string,
         hex_string_as_object_id,
         rfc3339_string_as_bson_datetime,
+        serialize_object_id_as_hex_string,
         timestamp_as_u32,
         u32_as_timestamp,
     },
@@ -898,3 +899,19 @@ fn large_dates() {
         &DateTime::MIN
     );
 }
+
+#[test]
+fn oid_as_hex_string() {
+    let _guard = LOCK.run_concurrently();
+
+    #[derive(Serialize)]
+    struct Foo {
+        #[serde(serialize_with = "serialize_object_id_as_hex_string")]
+        oid: ObjectId,
+    }
+
+    let oid = ObjectId::new();
+    let foo = Foo { oid };
+    let doc = to_document(&foo).unwrap();
+    assert_eq!(doc.get_str("oid").unwrap(), oid.to_hex());
+}