fix(csharp/src/Drivers/BigQuery): Fix failure when returning multiple table schemas from BigQuery

csharp/src/Drivers/BigQuery/BigQueryConnection.cs

@@ -38,8 +38,8 @@
     public class BigQueryConnection : AdbcConnection
     {
         readonly IReadOnlyDictionary<string, string> properties;
         BigQueryClient? client;
         GoogleCredential? credential;
 
         const string infoDriverName = "ADBC BigQuery Driver";
         const string infoDriverVersion = "1.0.0";
@@ -221,7 +221,7 @@
                 new Int64Array.Builder().Build(),
                 new Int32Array.Builder().Build(),
                 new ListArray.Builder(StringType.Default).Build(),
                 CreateNestedListArray(new List<IArrowArray?>(){ entriesDataArray }, entryType)
             };
 
             DenseUnionArray infoValue = new DenseUnionArray(infoUnionType, arrayLength, childrenArrays, typeBuilder.Build(), offsetBuilder.Build(), nullCount);
@@ -258,7 +258,7 @@
             string columnNamePattern)
         {
             StringArray.Builder catalogNameBuilder = new StringArray.Builder();
             List<IArrowArray?> catalogDbSchemasValues = new List<IArrowArray?>();
             string catalogRegexp = PatternToRegEx(catalogPattern);
             PagedEnumerable<ProjectList, CloudProject> catalogs = this.client.ListProjects();
 
@@ -988,47 +988,44 @@
             IArrowTypeVisitor<ListType>,
             IArrowTypeVisitor<FixedSizeListType>,
             IArrowTypeVisitor<StructType>,
-            IArrowTypeVisitor<UnionType>,
             IArrowTypeVisitor<MapType>
         {
             public ArrayData Result { get; private set; }
 
-            const int Length = 0;
-
             public void Visit(BooleanType type)
             {
-                Result = new ArrayData(type, Length, Length, 0, new[] { ArrowBuffer.Empty, ArrowBuffer.Empty });
+                Result = new BooleanArray.Builder().Build().Data;
             }
 
             public void Visit(FixedWidthType type)
             {
-                Result = new ArrayData(type, Length, Length, 0, new[] { ArrowBuffer.Empty, ArrowBuffer.Empty });
+                Result = new ArrayData(type, 0, 0, 0, new[] { ArrowBuffer.Empty, ArrowBuffer.Empty });
             }
 
             public void Visit(BinaryType type)
             {
-                Result = new ArrayData(type, Length, Length, 0, new[] { ArrowBuffer.Empty, ArrowBuffer.Empty, ArrowBuffer.Empty });
+                Result = new BinaryArray.Builder().Build().Data;
             }
 
             public void Visit(StringType type)
             {
-                Result = new ArrayData(type, Length, Length, 0, new[] { ArrowBuffer.Empty, ArrowBuffer.Empty, ArrowBuffer.Empty });
+                Result = new StringArray.Builder().Build().Data;
             }
 
             public void Visit(ListType type)
             {
                 type.ValueDataType.Accept(this);
                 ArrayData child = Result;
 
-                Result = new ArrayData(type, Length, Length, 0, new[] { ArrowBuffer.Empty, ArrowBuffer.Empty }, new[] { child });
+                Result = new ArrayData(type, 0, 0, 0, new[] { ArrowBuffer.Empty, MakeInt0Buffer() }, new[] { child });
             }
 
             public void Visit(FixedSizeListType type)
             {
                 type.ValueDataType.Accept(this);
                 ArrayData child = Result;
 
-                Result = new ArrayData(type, Length, Length, 0, new[] { ArrowBuffer.Empty }, new[] { child });
+                Result = new ArrayData(type, 0, 0, 0, new[] { ArrowBuffer.Empty }, new[] { child });
             }
 
             public void Visit(StructType type)
@@ -1040,50 +1037,25 @@
                     children[i] = Result;
                 }
 
-                Result = new ArrayData(type, Length, Length, 0, new[] { ArrowBuffer.Empty }, children);
-            }
-
-            public void Visit(UnionType type)
-            {
-                int bufferCount = type.Mode switch
-                {
-                    UnionMode.Sparse => 1,
-                    UnionMode.Dense => 2,
-                    _ => throw new InvalidOperationException($"Unknown UnionMode {type.Mode}"),
-                };
-
-                ArrayData[] children = new ArrayData[type.Fields.Count];
-                for (int i = 0; i < type.Fields.Count; i++)
-                {
-                    type.Fields[i].DataType.Accept(this);
-                    children[i] = Result;
-                }
-
-                ArrowBuffer[] buffers = new ArrowBuffer[bufferCount];
-                buffers[0] = ArrowBuffer.Empty;
-                if (bufferCount > 1)
-                {
-                    buffers[1] = ArrowBuffer.Empty;
-                }
-
-                Result = new ArrayData(type, Length, Length, 0, buffers, children);
+                Result = new ArrayData(type, 0, 0, 0, new[] { ArrowBuffer.Empty }, children);
             }
 
             public void Visit(MapType type)
             {
-                ArrayData[] children = new ArrayData[2];
-                type.KeyField.DataType.Accept(this);
-                children[0] = Result;
-                type.ValueField.DataType.Accept(this);
-                children[1] = Result;
-
-                Result = new ArrayData(type, Length, Length, 0, new[] { ArrowBuffer.Empty }, children);
+                Result = new MapArray.Builder(type).Build().Data;
             }
 
             public void Visit(IArrowType type)
             {
                 throw new NotImplementedException($"EmptyArrayCreationVisitor for {type.Name} is not supported yet.");
             }
+
+            private static ArrowBuffer MakeInt0Buffer()
+            {
+                ArrowBuffer.Builder<int> builder = new ArrowBuffer.Builder<int>();
+                builder.Append(0);
+                return builder.Build();
+            }
         }
     }
 }