tobixdev commented on code in PR #8829:
URL: https://github.com/apache/arrow-rs/pull/8829#discussion_r2520071255
##########
arrow-cast/src/pretty.rs:
##########
@@ -1283,4 +1428,247 @@ mod tests {
let actual: Vec<&str> = iso.lines().collect();
assert_eq!(expected_iso, actual, "Actual result:\n{iso}");
}
+
+ //
+ // Custom Formatting
+ //
+
+ /// The factory that will create the [`ArrayFormatter`]s.
+ struct TestFormatters {}
+
+ impl ArrayFormatterFactory for TestFormatters {
+ fn create_display_index<'formatter>(
+ &self,
+ array: &'formatter dyn Array,
+ options: &'formatter FormatOptions<'formatter>,
+ field: Option<&'formatter Field>,
+ ) -> Result<Option<ArrayFormatter<'formatter>>, ArrowError> {
+ if field
+ .map(|f| f.extension_type_name() == Some("my_money"))
+ .unwrap_or(false)
+ {
+ // We assume that my_money always is an Int32.
+ let array = array.as_primitive();
+ let display_index = Box::new(MyMoneyFormatter { array, options
});
+ return Ok(Some(ArrayFormatter::new(display_index,
options.safe)));
+ }
+
+ if array.data_type() == &DataType::Int32 {
+ // We assume that my_money always is an Int32.
+ let array = array.as_primitive();
+ let display_index = Box::new(MyInt32Formatter { array, options
});
+ return Ok(Some(ArrayFormatter::new(display_index,
options.safe)));
+ }
+
+ Ok(None)
+ }
+ }
+
+ /// The actual formatter
+ struct MyMoneyFormatter<'a> {
+ array: &'a Int32Array,
+ options: &'a FormatOptions<'a>,
+ }
+
+ impl<'a> DisplayIndex for MyMoneyFormatter<'a> {
+ fn write(&self, idx: usize, f: &mut dyn Write) ->
crate::display::FormatResult {
+ match self.array.is_valid(idx) {
+ true => write!(f, "{} €", self.array.value(idx))?,
+ false => write!(f, "{}", self.options.null)?,
+ }
+
+ Ok(())
+ }
+ }
+
+ /// The actual formatter
+ struct MyInt32Formatter<'a> {
+ array: &'a Int32Array,
+ options: &'a FormatOptions<'a>,
+ }
+
+ impl<'a> DisplayIndex for MyInt32Formatter<'a> {
+ fn write(&self, idx: usize, f: &mut dyn Write) ->
crate::display::FormatResult {
+ match self.array.is_valid(idx) {
+ true => write!(f, "{} (32-Bit)", self.array.value(idx))?,
+ false => write!(f, "{}", self.options.null)?,
+ }
+
+ Ok(())
+ }
+ }
+
+ #[test]
+ fn test_format_batches_with_custom_formatters() {
+ // define a schema.
+ let options = FormatOptions::new().with_null("<NULL>");
+ let money_metadata = HashMap::from([(
+ extension::EXTENSION_TYPE_NAME_KEY.to_owned(),
+ "my_money".to_owned(),
+ )]);
+ let schema = Arc::new(Schema::new(vec![
+ Field::new("income", DataType::Int32,
true).with_metadata(money_metadata.clone()),
+ ]));
+
+ // define data.
+ let batch = RecordBatch::try_new(
+ schema,
+ vec![Arc::new(array::Int32Array::from(vec![
+ Some(1),
+ None,
+ Some(10),
+ Some(100),
+ ]))],
+ )
+ .unwrap();
+
+ let mut buf = String::new();
+ write!(
+ &mut buf,
+ "{}",
+ pretty_format_batches_with_options_and_formatters(
+ &[batch],
+ &options,
+ Some(&TestFormatters {})
+ )
+ .unwrap()
+ )
+ .unwrap();
+
+ let s = [
+ "+--------+",
Review Comment:
Pretty-printing result with a custom extension type
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