ysuliu commented on issue #625:
URL: https://github.com/apache/arrow-go/issues/625#issuecomment-3758338432
Hi @zeroshade ,
Thanks for the comments. Now I get to know `IsNull()` method should be used
for checking the values that were appended by `AppendNull()`.
But sorry that I got the new case about `Append(nil)`:
```go
idBuilder.Append([]byte{}) // empty slice
idBuilder.Append(nil) // append 'nil'
idBuilder.AppendNull() // NULL
```
`Append(nil)` seems to be different from `AppendNull()`, because `IsNull()`
will be `true` for `AppendNull()`, but `false` for `Append(nil)`.
Then with the code:
```go
data, _ := col.(*array.Binary)
if data.IsNull(rowIdx) {
fmt.Print("NULL\n")
} else if data.Value(rowIdx) == nil {
fmt.Print("nil\n")
} else {
fmt.Printf("value: %v\n",
data.Value(rowIdx))
}
```
Without the fix, the result for _both_ cases is:
```
nil
nil
NULL
```
With the fix, the result for _both_ cases is:
```
value: []
value: []
NULL
```
So it seems that we still can't distinguish between empty slice `[]byte{}`
and `nil`. Can you suggest further?
Thanks a lot!
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