GH-37643: [C++] Enhance arrow::Datum::ToString (#37646)

### Rationale for this change Add print child fields for `arrow::Datum::ToString`. Because previously it just print a type. ### What changes are included in this PR? Add detail in `arrow::Datum::ToString` ### Are these changes tested? no ### Are there any user-facing changes? Yes * Closes: #37643 Authored-by: mwish <[email protected]> Signed-off-by: Benjamin Kietzman <[email protected]>
apache · Sep 15, 2023 · d9ee3a7 · d9ee3a7
1 parent ac7e9a4
commit d9ee3a7
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Showing 8 changed files with 21 additions and 13 deletions.
diff --git a/c_glib/test/test-array-datum.rb b/c_glib/test/test-array-datum.rb
@@ -61,7 +61,7 @@ def test_false
   end
 
   def test_to_string
-    assert_equal("Array", @datum.to_s)
+    assert_equal("Array([\n" + "  true,\n" + "  false\n" + "])", @datum.to_s)
   end
 
   def test_value

diff --git a/c_glib/test/test-chunked-array-datum.rb b/c_glib/test/test-chunked-array-datum.rb
@@ -49,7 +49,7 @@ def test_false
   end
 
   def test_to_string
-    assert_equal("ChunkedArray", @datum.to_s)
+    assert_equal("ChunkedArray([\n" + "  [\n" + "    true,\n" + "    false\n" + "  ]\n" + "])", @datum.to_s)
   end
 
   def test_value

diff --git a/c_glib/test/test-record-batch-datum.rb b/c_glib/test/test-record-batch-datum.rb
@@ -49,7 +49,7 @@ def test_false
   end
 
   def test_to_string
-    assert_equal("RecordBatch", @datum.to_s)
+    assert_equal("RecordBatch(visible:   [\n" + "    true,\n" + "    false\n" + "  ]\n" + ")", @datum.to_s)
   end
 
   def test_value

diff --git a/c_glib/test/test-scalar-datum.rb b/c_glib/test/test-scalar-datum.rb
@@ -60,7 +60,7 @@ def test_false
   end
 
   def test_to_string
-    assert_equal("Scalar", @datum.to_s)
+    assert_equal("Scalar(true)", @datum.to_s)
   end
 
   def test_value

diff --git a/c_glib/test/test-table-datum.rb b/c_glib/test/test-table-datum.rb
@@ -49,7 +49,16 @@ def test_false
   end
 
   def test_to_string
-    assert_equal("Table", @datum.to_s)
+    assert_equal("Table(visible: bool\n" +
+    "----\n" +
+    "visible:\n" +
+    "  [\n" +
+    "    [\n" +
+    "      true,\n" +
+    "      false\n" +
+    "    ]\n" +
+    "  ]\n" +
+    ")", @datum.to_s)
   end
 
   def test_value

diff --git a/cpp/src/arrow/datum.cc b/cpp/src/arrow/datum.cc
@@ -182,15 +182,15 @@ std::string Datum::ToString() const {
     case Datum::NONE:
       return "nullptr";
     case Datum::SCALAR:
-      return "Scalar";
+      return "Scalar(" + scalar()->ToString() + ")";
     case Datum::ARRAY:
-      return "Array";
+      return "Array(" + make_array()->ToString() + ")";
     case Datum::CHUNKED_ARRAY:
-      return "ChunkedArray";
+      return "ChunkedArray(" + chunked_array()->ToString() + ")";
     case Datum::RECORD_BATCH:
-      return "RecordBatch";
+      return "RecordBatch(" + record_batch()->ToString() + ")";
     case Datum::TABLE:
-      return "Table";
+      return "Table(" + table()->ToString() + ")";
     default:
       DCHECK(false);
       return "";

diff --git a/cpp/src/arrow/datum.h b/cpp/src/arrow/datum.h
@@ -301,7 +301,6 @@ struct ARROW_EXPORT Datum {
   bool operator==(const Datum& other) const { return Equals(other); }
   bool operator!=(const Datum& other) const { return !Equals(other); }
 
-  /// \brief Return a string representation of the kind of datum stored.
   std::string ToString() const;
 };
 

diff --git a/cpp/src/arrow/datum_test.cc b/cpp/src/arrow/datum_test.cc
@@ -154,8 +154,8 @@ TEST(Datum, ToString) {
   Datum v1(arr);
   Datum v2(std::make_shared<Int8Scalar>(1));
 
-  ASSERT_EQ("Array", v1.ToString());
-  ASSERT_EQ("Scalar", v2.ToString());
+  ASSERT_EQ("Array([\n  1,\n  2,\n  3,\n  4\n])", v1.ToString());
+  ASSERT_EQ("Scalar(1)", v2.ToString());
 }
 
 TEST(Datum, TotalBufferSize) {