alamb commented on code in PR #9798:
URL: https://github.com/apache/arrow-datafusion/pull/9798#discussion_r1538519670
##########
datafusion/sql/src/unparser/expr.rs:
##########
@@ -113,10 +113,38 @@ impl Unparser<'_> {
}
Expr::Case(Case {
expr,
- when_then_expr: _,
- else_expr: _,
+ when_then_expr,
+ else_expr,
}) => {
- not_impl_err!("Unsupported expression: {expr:?}")
+ let conditions = when_then_expr
+ .iter()
+ .map(|(w, _)| self.expr_to_sql(w))
+ .collect::<Result<Vec<_>>>()?;
+ let results = when_then_expr
+ .iter()
+ .map(|(_, t)| self.expr_to_sql(t))
+ .collect::<Result<Vec<_>>>()?;
Review Comment:
I likewise tried to use `izip` and came up with this, which wasn't
particularly nice
```rust
let (conditions, results): (Vec<_>, Vec<_>) = when_then_expr
.iter()
.map(|(w, t)| (self.expr_to_sql(w), self.expr_to_sql(t)))
.unzip();
let conditions =
conditions.into_iter().collect::<Result<Vec<_>>>()?;
let results =
results.into_iter().collect::<Result<Vec<_>>>()?;
```
This is the best I could come up with but I am not sure how much better it
is:
```rust
let mut conditions = vec![];
let mut results = vec[]!;
for (w, t) in when_then_expr {
conditions.push(self.expr_to_sql(w)?);
results.push(self.expr_to_sql(t)?);
}
```
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