alamb commented on code in PR #14167:
URL: https://github.com/apache/datafusion/pull/14167#discussion_r1921063517
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datafusion/common/src/scalar/mod.rs:
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@@ -2849,6 +2849,50 @@ impl ScalarValue {
ScalarValue::from(value).cast_to(target_type)
}
+ /// Returns the Some(`&str`) representation of `ScalarValue` of logical
string type
+ ///
+ /// Returns `None` if this `ScalarValue` is not a logical string type or
the
+ /// `ScalarValue` represents the `NULL` value.
+ ///
+ /// Note you can use [`Option::flatten`] to check for non null logical
+ /// strings.
+ ///
+ /// For example, [`ScalarValue::Utf8`], [`ScalarValue::LargeUtf8`], and
+ /// [`ScalarValue::Dictionary`] with a logical string value and store
+ /// strings and can be accessed as `&str` using this method.
+ ///
+ /// # Example: logical strings
+ /// ```
+ /// # use datafusion_common::ScalarValue;
+ /// /// non strings return None
+ /// let scalar = ScalarValue::from(42);
+ /// assert_eq!(scalar.try_as_str(), None);
+ /// // Non null logical string returns Some(Some(&str))
+ /// let scalar = ScalarValue::from("hello");
+ /// assert_eq!(scalar.try_as_str(), Some(Some("hello")));
+ /// // Null logical string returns Some(None)
+ /// let scalar = ScalarValue::Utf8(None);
+ /// assert_eq!(scalar.try_as_str(), Some(None));
+ /// ```
+ ///
+ /// # Example: use [`Option::flatten`] to check for non-null logical
strings
+ /// ```
+ /// # use datafusion_common::ScalarValue;
+ /// // Non null logical string returns Some(Some(&str))
+ /// let scalar = ScalarValue::from("hello");
+ /// assert_eq!(scalar.try_as_str().flatten(), Some("hello"));
+ /// ```
+ pub fn try_as_str(&self) -> Option<Option<&str>> {
Review Comment:
Thank you for the review @wiedld
`DataFusionError` always has an owned String in it, so returning an `Result`
is actually quite slow as it needs to allocate some memory and copy stuff
around. Thus I think this API should return an `Option`
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