feat: add duration type to json writer (#1522)

src/io/json/write/serialize.rs

@@ -1,4 +1,4 @@
-use chrono::{NaiveDate, NaiveDateTime};
+use chrono::{Duration, NaiveDate, NaiveDateTime};
 use lexical_core::ToLexical;
 use std::io::Write;
 use streaming_iterator::StreamingIterator;
@@ -8,8 +8,9 @@ use crate::datatypes::{IntegerType, TimeUnit};
 use crate::io::iterator::BufStreamingIterator;
 use crate::offset::Offset;
 use crate::temporal_conversions::{
-    date32_to_date, date64_to_date, timestamp_ms_to_datetime, timestamp_ns_to_datetime,
-    timestamp_s_to_datetime, timestamp_us_to_datetime,
+    date32_to_date, date64_to_date, duration_ms_to_duration, duration_ns_to_duration,
+    duration_s_to_duration, duration_us_to_duration, timestamp_ms_to_datetime,
+    timestamp_ns_to_datetime, timestamp_s_to_datetime, timestamp_us_to_datetime,
 };
 use crate::util::lexical_to_bytes_mut;
 use crate::{array::*, datatypes::DataType, types::NativeType};
@@ -266,6 +267,28 @@ where
     materialize_serializer(f, array.iter(), offset, take)
 }
 
+fn duration_serializer<'a, T, F>(
+    array: &'a PrimitiveArray<T>,
+    convert: F,
+    offset: usize,
+    take: usize,
+) -> Box<dyn StreamingIterator<Item = [u8]> + 'a + Send + Sync>
+where
+    T: NativeType,
+    F: Fn(T) -> Duration + 'static + Send + Sync,
+{
+    let f = move |x: Option<&T>, buf: &mut Vec<u8>| {
+        if let Some(x) = x {
+            let duration = convert(*x);
+            write!(buf, "\"{duration}\"").unwrap();
+        } else {
+            buf.extend_from_slice(b"null")
+        }
+    };
+
+    materialize_serializer(f, array.iter(), offset, take)
+}
+
 fn timestamp_serializer<'a, F>(
     array: &'a PrimitiveArray<i64>,
     convert: F,
@@ -385,6 +408,20 @@ pub(crate) fn new_serializer<'a>(
                 )
             }
         }
+        DataType::Duration(tu) => {
+            let convert = match tu {
+                TimeUnit::Nanosecond => duration_ns_to_duration,
+                TimeUnit::Microsecond => duration_us_to_duration,
+                TimeUnit::Millisecond => duration_ms_to_duration,
+                TimeUnit::Second => duration_s_to_duration,
+            };
+            duration_serializer(
+                array.as_any().downcast_ref().unwrap(),
+                convert,
+                offset,
+                take,
+            )
+        }
         DataType::Null => null_serializer(array.len(), offset, take),
         other => todo!("Writing {:?} to JSON", other),
     }

src/temporal_conversions.rs

@@ -2,7 +2,7 @@
 
 use chrono::{
     format::{parse, Parsed, StrftimeItems},
-    Datelike, FixedOffset, NaiveDate, NaiveDateTime, NaiveTime,
+    Datelike, Duration, FixedOffset, NaiveDate, NaiveDateTime, NaiveTime,
 };
 
 use crate::error::Result;
@@ -66,6 +66,30 @@ pub fn time32s_to_time(v: i32) -> NaiveTime {
     NaiveTime::from_num_seconds_from_midnight_opt(v as u32, 0).expect("invalid time")
 }
 
+/// converts a `i64` representing a `duration(s)` to [`Duration`]
+#[inline]
+pub fn duration_s_to_duration(v: i64) -> Duration {
+    Duration::seconds(v)
+}
+
+/// converts a `i64` representing a `duration(ms)` to [`Duration`]
+#[inline]
+pub fn duration_ms_to_duration(v: i64) -> Duration {
+    Duration::milliseconds(v)
+}
+
+/// converts a `i64` representing a `duration(us)` to [`Duration`]
+#[inline]
+pub fn duration_us_to_duration(v: i64) -> Duration {
+    Duration::microseconds(v)
+}
+
+/// converts a `i64` representing a `duration(ns)` to [`Duration`]
+#[inline]
+pub fn duration_ns_to_duration(v: i64) -> Duration {
+    Duration::nanoseconds(v)
+}
+
 /// converts a `i32` representing a `time32(ms)` to [`NaiveTime`]
 #[inline]
 pub fn time32ms_to_time(v: i32) -> NaiveTime {