alamb opened a new issue #597:
URL: https://github.com/apache/arrow-rs/issues/597
**Describe the bug**
I can not create a `PrimitiveArray` that has a `DataType::Timestamp` with a
timezone other than `None`
**To Reproduce**
I am trying to pretty print an array that has timestamps using UTC time.
So instead of `1970-01-01 00:00:00.000000100` I want to print something more
like the following (note the Z, in RFC3339): `1970-01-01T00:00:00.000000100Z`
To do so I figured I would "simply" create a new array that had a Timestamp
type with the timezone set to UTC
`TimestampNanosecondArray` is defined like this:
```rust
pub type TimestampNanosecondArray = PrimitiveArray<TimestampNanosecondType>;
```
And `TimestampNanosecondType` is (effectively) something like
```rust
struct TimestampNanosecondType {}
impl ArrowPrimitiveType for TimestampNanosecondType {
type Native = i64;
const DATA_TYPE = DataType::Timestamp(TimeUnit::Nanosecond, None)
}
```
So I figured I would make a
`PrimitiveArray<SOME_TYPE_THAT_HAD_MY_TIMEZONE_SPECIFIED>`
```rust
struct TimestampUtcNanosecondType {}
impl ArrowPrimitiveType for TimestampUtcNanosecondType {
type Native = i64;
const DATA_TYPE: DataType = DataType::Timestamp(TimeUnit::Nanosecond,
Some("+00:00".to_string()));
}
```
Uhoh! The compiler doesn't like that because it needs a `const String` which
you can't have....
```
error[E0015]: calls in constants are limited to constant functions, tuple
structs and tuple variants
--> src/main.rs:38:80
|
38 | const DATA_TYPE: DataType =
DataType::Timestamp(TimeUnit::Nanosecond, Some("+00:00".to_string()));
|
^^^^^^^^^^^^^^^^^^^^
```
So I conclude it is basically impossible to create an array with a timezone
other than `None`
**Expected behavior**
I expect to be able to create an array using a timezone
**Proposal**
Proposal:
Change `DataType::Timestamp` from
```rust
Timestamp(TimeUnit, Option<String>),
```
to
```rust
Timestamp(TimeUnit, Option<&static str>),
```
**Additional context**
FWIW I also tried using `lazy_static` but it doesn't provide a `const
String` (only a `static String`)
I view this as a potential first step towards handling timestamps properly
in arrow and datafusion: https://github.com/apache/arrow-datafusion/issues/686
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