odbtest/test/arrow/stru.go

package main

import (
	"fmt"

	"github.com/apache/arrow/go/arrow"
	"github.com/apache/arrow/go/arrow/array"
	"github.com/apache/arrow/go/arrow/memory"
)

func main() {
	pool := memory.NewGoAllocator()

	dtype := arrow.StructOf([]arrow.Field{
		{Name: "f1", Type: arrow.ListOf(arrow.PrimitiveTypes.Uint8)},
		{Name: "f2", Type: arrow.PrimitiveTypes.Int32},
	}...)

	sb := array.NewStructBuilder(pool, dtype)
	defer sb.Release()

	f1b := sb.FieldBuilder(0).(*array.ListBuilder)
	defer f1b.Release()
	f1vb := f1b.ValueBuilder().(*array.Uint8Builder)
	defer f1vb.Release()

	f2b := sb.FieldBuilder(1).(*array.Int32Builder)
	defer f2b.Release()

	sb.Reserve(4)
	f1vb.Reserve(7)
	f2b.Reserve(3)

	sb.Append(true)
	f1b.Append(true)
	f1vb.AppendValues([]byte("joe"), nil)
	f2b.Append(1)

	sb.Append(true)
	f1b.AppendNull()
	f2b.Append(2)

	sb.AppendNull()

	sb.Append(true)
	f1b.Append(true)
	f1vb.AppendValues([]byte("mark"), nil)
	f2b.Append(4)

	arr := sb.NewArray().(*array.Struct)
	defer arr.Release()

	fmt.Printf("NullN() = %d\n", arr.NullN())
	fmt.Printf("Len()   = %d\n", arr.Len())

	list := arr.Field(0).(*array.List)
	defer list.Release()

	offsets := list.Offsets()

	varr := list.ListValues().(*array.Uint8)
	defer varr.Release()

	ints := arr.Field(1).(*array.Int32)
	defer ints.Release()

	for i := 0; i < arr.Len(); i++ {
		if !arr.IsValid(i) {
			fmt.Printf("Struct[%d] = (null)\n", i)
			continue
		}
		fmt.Printf("Struct[%d] = [", i)
		pos := int(offsets[i])
		switch {
		case list.IsValid(pos):
			fmt.Printf("[")
			for j := offsets[i]; j < offsets[i+1]; j++ {
				if j != offsets[i] {
					fmt.Printf(", ")
				}
				fmt.Printf("%v", string(varr.Value(int(j))))
			}
			fmt.Printf("], ")
		default:
			fmt.Printf("(null), ")
		}
		fmt.Printf("%d]\n", ints.Value(i))
	}

}