Implement unparse ScalarVariable to String (#10541)

* Implement unparse `ScalarVariable` to String * remove quote_style --------- Co-authored-by: Andrew Lamb <[email protected]>
apache · May 17, 2024 · ea023e2 · ea023e2
1 parent d2fb05e
commit ea023e2
Showing 1 changed file with 35 additions and 2 deletions.
diff --git a/datafusion/sql/src/unparser/expr.rs b/datafusion/sql/src/unparser/expr.rs
@@ -394,8 +394,22 @@ impl Unparser<'_> {
                     expr: Box::new(sql_parser_expr),
                 })
             }
-            Expr::ScalarVariable(_, _) => {
-                not_impl_err!("Unsupported Expr conversion: {expr:?}")
+            Expr::ScalarVariable(_, ids) => {
+                if ids.is_empty() {
+                    return internal_err!("Not a valid ScalarVariable");
+                }
+
+                Ok(if ids.len() == 1 {
+                    ast::Expr::Identifier(
+                        self.new_ident_without_quote_style(ids[0].to_string()),
+                    )
+                } else {
+                    ast::Expr::CompoundIdentifier(
+                        ids.iter()
+                            .map(|i| self.new_ident_without_quote_style(i.to_string()))
+                            .collect(),
+                    )
+                })
             }
             Expr::GetIndexedField(_) => {
                 not_impl_err!("Unsupported Expr conversion: {expr:?}")
@@ -497,6 +511,13 @@ impl Unparser<'_> {
         }
     }
 
+    pub(super) fn new_ident_without_quote_style(&self, str: String) -> ast::Ident {
+        ast::Ident {
+            value: str,
+            quote_style: None,
+        }
+    }
+
     pub(super) fn binary_op_to_sql(
         &self,
         lhs: ast::Expr,
@@ -868,6 +889,7 @@ mod tests {
     use std::{any::Any, sync::Arc, vec};
 
     use arrow::datatypes::{Field, Schema};
+    use arrow_schema::DataType::Int8;
     use datafusion_common::TableReference;
     use datafusion_expr::{
         case, col, exists,
@@ -1158,6 +1180,17 @@ mod tests {
                 try_cast(col("a"), DataType::UInt32),
                 r#"TRY_CAST("a" AS INTEGER UNSIGNED)"#,
             ),
+            (
+                Expr::ScalarVariable(Int8, vec![String::from("@a")]),
+                r#"@a"#,
+            ),
+            (
+                Expr::ScalarVariable(
+                    Int8,
+                    vec![String::from("@root"), String::from("foo")],
+                ),
+                r#"@root.foo"#,
+            ),
             (col("x").eq(placeholder("$1")), r#"("x" = $1)"#),
             (
                 out_ref_col(DataType::Int32, "t.a").gt(lit(1)),