alamb commented on code in PR #9298:
URL: https://github.com/apache/arrow-datafusion/pull/9298#discussion_r1497030514
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datafusion/functions/src/core/arrow_cast.rs:
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@@ -19,16 +19,65 @@
//! casting to arbitrary arrow types (rather than SQL types)
use std::{fmt::Display, iter::Peekable, str::Chars, sync::Arc};
+use std::any::Any;
+use arrow::compute::cast;
use arrow_schema::{DataType, Field, IntervalUnit, TimeUnit};
-use datafusion_common::{
- plan_datafusion_err, DFSchema, DataFusionError, Result, ScalarValue,
-};
+use datafusion_common::{plan_datafusion_err, DataFusionError, Result,
ScalarValue, ExprSchema, plan_err};
-use datafusion_common::plan_err;
-use datafusion_expr::{Expr, ExprSchemable};
+use datafusion_expr::{ColumnarValue, Expr, ScalarUDFImpl, Signature,
Volatility};
-pub const ARROW_CAST_NAME: &str = "arrow_cast";
+#[derive(Debug)]
+pub(super) struct ArrowCastFunc {
+ signature: Signature,
+}
+
+impl ArrowCastFunc {
+ pub fn new() -> Self{
+ Self {
+ signature:
+ Signature::any(2, Volatility::Immutable)
+ }
+ }
+
+}
+
+impl ScalarUDFImpl for ArrowCastFunc {
+ fn as_any(&self) -> &dyn Any {
+ self
+ }
+
+ fn name(&self) -> &str {
+ "arrow_cast"
+ }
+
+ fn signature(&self) -> &Signature {
+ &self.signature
+ }
+
+ fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
+ parse_data_type(&arg_types[1].to_string())
+ }
+
+ fn return_type_from_exprs(&self, args: &[Expr], _schema: &dyn ExprSchema)
-> Result<DataType> {
+ if args.len() != 2 {
+ return plan_err!("arrow_cast needs 2 arguments, {} provided",
args.len());
+ }
+ let arg1 = args.get(1);
+
+ match arg1 {
+ Some(Expr::Literal(ScalarValue::Utf8(arg1))) => {
+ let data_type = parse_data_type(
arg1.clone().unwrap().as_str())?;
Review Comment:
Can we avoid this `unwrap`? As written I think this will panic if a `null`
is passed in
I think you can do so by matching on `Some`
```suggestion
Some(Expr::Literal(ScalarValue::Utf8(Some(arg1)))) => {
let data_type = parse_data_type(arg1)?;
```
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