Platob commented on code in PR #35153:
URL: https://github.com/apache/arrow/pull/35153#discussion_r1170217707
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csharp/src/Apache.Arrow/Field.Builder.cs:
##########
@@ -52,6 +55,131 @@ public Builder DataType(IArrowType type)
return this;
}
+ // Build DataType from C# Type
+ public Builder DataType(System.Type valueType, string timezone =
null)
+ {
+ System.Type[] genericArgs;
+ System.Type child =
System.Nullable.GetUnderlyingType(valueType);
+ Type elementType;
+
+ if (child != null)
+ {
+ // Nullable Type
+ DataType(child, timezone);
+ Nullable(true);
+ return this;
+ }
+
+ // Not Nullable Type
+ Nullable(false);
+
+ switch (valueType)
+ {
+ // Binary
+ case var _ when valueType == typeof(byte):
+ DataType(new BinaryType());
+ break;
+ case var _ when valueType == typeof(IEnumerable<byte>):
+ DataType(new BinaryType());
+ Nullable(true);
+ break;
+ // Boolean
+ case var _ when valueType == typeof(bool):
+ DataType(new BooleanType());
+ break;
+ // String
+ case var _ when valueType == typeof(string):
+ DataType(new StringType());
+ Nullable(true);
+ break;
+ // Integers
+ case var _ when valueType == typeof(sbyte):
+ DataType(new Int8Type());
+ break;
+ case var _ when valueType == typeof(short):
+ DataType(new Int16Type());
+ break;
+ case var _ when valueType == typeof(int):
+ DataType(new Int32Type());
+ break;
+ case var _ when valueType == typeof(long):
+ DataType(new Int64Type());
+ break;
+ // Unisgned Integers
+ case var _ when valueType == typeof(ushort):
+ DataType(new UInt16Type());
+ break;
+ case var _ when valueType == typeof(uint):
+ DataType(new UInt32Type());
+ break;
+ case var _ when valueType == typeof(ulong):
+ DataType(new UInt64Type());
+ break;
+ // Decimal
+ case var _ when valueType == typeof(decimal):
+ DataType(Decimal256Type.Default);
+ break;
+ // Float
+ case var _ when valueType == typeof(float):
+ DataType(new FloatType());
+ break;
+ // Double
+ case var _ when valueType == typeof(double):
+ DataType(new DoubleType());
+ break;
+ // DateTime
+ case var _ when valueType == typeof(DateTime) || valueType
== typeof(DateTimeOffset):
+ DataType(new TimestampType(TimeUnit.Nanosecond,
timezone));
+ break;
+ // Time
+ case var _ when valueType == typeof(TimeSpan):
+ DataType(new Time64Type(TimeUnit.Nanosecond));
+ break;
+#if NETCOREAPP3_1_OR_GREATER
+ // Dictionary: IDictionary<?,?>
+ case var dict when
typeof(IDictionary).IsAssignableFrom(valueType):
+ genericArgs = dict.GetGenericArguments();
+
+ DataType(new DictionaryType(
+ new Builder().DataType(genericArgs[0],
timezone)._type,
+ new Builder().DataType(genericArgs[1],
timezone)._type,
+ false
+ ));
+
+ Nullable(true);
+
+ break;
+ // IEnumerable: List, Array, ...
+ case var list when
typeof(IEnumerable).IsAssignableFrom(valueType):
+ elementType = list.GetGenericArguments()[0];
+
+ DataType(new ListType(new
Builder().Name("item").DataType(elementType, timezone).Build()));
+
+ Nullable(true);
+ break;
+ // Struct like: get all properties
+ case var structure when (valueType.IsValueType &&
!valueType.IsEnum && !valueType.IsPrimitive):
+ if (string.IsNullOrEmpty(_name))
+ Name(structure.Name);
+
+ PropertyInfo[] properties =
structure.GetProperties(BindingFlags.Instance | BindingFlags.Public |
BindingFlags.NonPublic);
+
+ DataType(new StructType(
+ properties
+ .Select(property => new
Builder().Name(property.Name).DataType(property.PropertyType, timezone).Build())
+ .ToArray()
+ ));
+
+ break;
Review Comment:
Apache Spark uses the same process in scala, its pretty usefull when later
you want statically type your Datasets which can be considered like arrow
RecordBatches
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