change example to keep using DateTime<Utc> and update playground hash.

Author: leonlux

_src/custom-date-format.md

@@ -4,27 +4,27 @@ This uses the [`chrono`](https://github.com/chronotope/chrono) crate to
 serialize and deserialize JSON data containing a custom date format. The `with`
 attribute is used to provide the logic for handling the custom representation.
 
-!PLAYGROUND 7185eb211a4822ce97184ae25fedda91
+!PLAYGROUND 8989865329b35bed5828ff7f7f4747f4
 ```rust
-use chrono::NaiveDateTime;
-use serde::{Serialize, Deserialize};
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct StructWithCustomDate {
     // DateTime supports Serde out of the box, but uses RFC3339 format. Provide
     // some custom logic to make it use our desired format.
     #[serde(with = "my_date_format")]
-    pub timestamp: NaiveDateTime,
+    pub timestamp: DateTime<Utc>,
 
     // Any other fields in the struct.
     pub bidder: String,
 }
 
 mod my_date_format {
-    use chrono::NaiveDateTime;
-    use serde::{self, Deserialize, Serializer, Deserializer};
+    use chrono::{DateTime, Utc};
+    use serde::{self, Deserialize, Deserializer, Serializer};
 
-    const FORMAT: &'static str = "%Y-%m-%d %H:%M:%S";
+    const FORMAT: &'static str = "%Y-%m-%d %H:%M:%S %z";
 
     // The signature of a serialize_with function must follow the pattern:
     //
@@ -33,10 +33,7 @@ mod my_date_format {
     //        S: Serializer
     //
     // although it may also be generic over the input types T.
-    pub fn serialize<S>(
-        date: &NaiveDateTime,
-        serializer: S,
-    ) -> Result<S::Ok, S::Error>
+    pub fn serialize<S>(date: &DateTime<Utc>, serializer: S) -> Result<S::Ok, S::Error>
         where
             S: Serializer,
     {
@@ -51,22 +48,21 @@ mod my_date_format {
     //        D: Deserializer<'de>
     //
     // although it may also be generic over the output types T.
-    pub fn deserialize<'de, D>(
-        deserializer: D,
-    ) -> Result<NaiveDateTime, D::Error>
+    pub fn deserialize<'de, D>(deserializer: D) -> Result<DateTime<Utc>, D::Error>
         where
             D: Deserializer<'de>,
     {
         let s = String::deserialize(deserializer)?;
-        NaiveDateTime::parse_from_str(&s, FORMAT).map_err(serde::de::Error::custom)
+        let date_fixed_offset =
+            DateTime::parse_from_str(&s, FORMAT).map_err(serde::de::Error::custom)?;
+        Ok(date_fixed_offset.with_timezone(&Utc))
     }
-
 }
 
 fn main() {
     let json_str = r#"
       {
-        "timestamp": "2017-02-16 21:54:30",
+        "timestamp": "2017-02-16 21:54:30 +00:00",
         "bidder": "Skrillex"
       }
     "#;