Support dictionary data type in array_to_string

datafusion/functions-array/src/string.rs

@@ -18,7 +18,7 @@
 //! [`ScalarUDFImpl`] definitions for array_to_string and string_to_array functions.
 
 use arrow::array::{
-    Array, ArrayRef, BooleanArray, Float32Array, Float64Array, GenericListArray,
+    Array, ArrayRef, AsArray, BooleanArray, Float32Array, Float64Array, GenericListArray,
     Int16Array, Int32Array, Int64Array, Int8Array, LargeStringArray, ListBuilder,
     OffsetSizeTrait, StringArray, StringBuilder, UInt16Array, UInt32Array, UInt64Array,
     UInt8Array,
@@ -31,7 +31,7 @@ use datafusion_common::{plan_err, DataFusionError, Result};
 use std::any::{type_name, Any};
 
 use crate::utils::{downcast_arg, make_scalar_function};
-use arrow_schema::DataType::{FixedSizeList, LargeList, LargeUtf8, List, Null, Utf8};
+use arrow_schema::DataType::{FixedSizeList, LargeList, LargeUtf8, List, Null, Utf8, Dictionary};
 use datafusion_common::cast::{
     as_generic_string_array, as_large_list_array, as_list_array, as_string_array,
 };
@@ -281,6 +281,31 @@ pub(super) fn array_to_string_inner(args: &[ArrayRef]) -> Result<ArrayRef> {
 
                 Ok(arg)
             }
+            Dictionary(..) => {
+                let any_dict_array = arr
+                    .as_any_dictionary_opt()
+                    .ok_or_else( || {
+                        DataFusionError::Internal(
+                            format!("could not cast {} to AnyDictionaryArray", arr.data_type())
+                        )
+                    })?;
+                macro_rules! array_function {
+                    ($ARRAY_TYPE:ident) => {
+                        to_string!(
+                            arg,
+                            any_dict_array.values(),
+                            &delimiter,
+                            &null_string,
+                            with_null_string,
+                            $ARRAY_TYPE
+                        )
+                    };
+                }
+                call_array_function!(
+                    any_dict_array.values().data_type(),
+                    false
+                )
+            }
             Null => Ok(arg),
             data_type => {
                 macro_rules! array_function {

datafusion/sqllogictest/test_files/array.slt

@@ -3769,6 +3769,22 @@ select array_to_string(make_array(), ',')
 ----
 (empty)
 
+# array to string dictionary
+statement ok
+CREATE TABLE table1 AS VALUES (1, arrow_cast('foo', 'Dictionary(Int32, Utf8)')), (2, arrow_cast('bar', 'Dictionary(Int32, Utf8)'));
+
+query T
+SELECT array_to_string(array_agg(column2),',') FROM (SELECT column2 FROM table1);
+----
+foo,bar
+
+statement ok
+CREATE TABLE table2 AS VALUES (1, arrow_cast(1, 'Dictionary(Int32, Int32)')), (2, arrow_cast(2, 'Dictionary(Int32, Int32)'));
+
+query T
+SELECT array_to_string(array_agg(column2),'-') FROM (SELECT column2 FROM table2);
+----
+1-2
 
 ## array_union (aliases: `list_union`)