ianmcook opened a new issue, #848:
URL: https://github.com/apache/arrow-go/issues/848
### Describe the bug, including details regarding any error messages,
version, and platform.
Example to reproduce this:
When an `decimal128(5, 2)` array contains the value `19.99`, the underlying
value is stored as integer `1999` with scale `2`. `ValueStr(0)` formats this
correctly as `19.99`, but `String()` on the decimal array, and therefore
`fmt.Println(recordBatch)`, prints the raw `decimal128.Num` value (`{1999 0}`):
```go
package main
import (
"fmt"
"log"
"github.com/apache/arrow-go/v18/arrow"
"github.com/apache/arrow-go/v18/arrow/array"
"github.com/apache/arrow-go/v18/arrow/decimal128"
"github.com/apache/arrow-go/v18/arrow/memory"
)
func main() {
typ := &arrow.Decimal128Type{Precision: 5, Scale: 2}
builder := array.NewDecimal128Builder(memory.DefaultAllocator, typ)
defer builder.Release()
value, err := decimal128.FromString("19.99", typ.Precision, typ.Scale)
if err != nil {
log.Fatal(err)
}
builder.Append(value)
decimalArray := builder.NewDecimal128Array()
defer decimalArray.Release()
fmt.Println("ValueStr:", decimalArray.ValueStr(0))
fmt.Println("Array String:", decimalArray)
schema := arrow.NewSchema([]arrow.Field{
{Name: "price", Type: typ},
}, nil)
record := array.NewRecordBatch(schema, []arrow.Array{decimalArray}, 1)
defer record.Release()
fmt.Println(record)
}
```
Actual output:
```text
ValueStr: 19.99
Array String: [{1999 0}]
record:
schema:
fields: 1
- price: type=decimal(5, 2)
rows: 1
col[0][price]: [{1999 0}]
```
Expected output would format the decimal using the array type's scale, for
example `19.99`, as `ValueStr(0)` already does.
Compare to PyArrow, which formats the same logical `decimal128(5, 2)` value
using the scale metadata:
```python
from decimal import Decimal
import pyarrow as pa
table = pa.table({
"price": pa.array([Decimal("19.99")], type=pa.decimal128(5, 2)),
})
print(table)
```
PyArrow output:
```text
pyarrow.Table
price: decimal128(5, 2)
----
price: [[19.99]]
```
### Component(s)
Other
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