alamb commented on a change in pull request #10063:
URL: https://github.com/apache/arrow/pull/10063#discussion_r614746235
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File path: rust/arrow/src/record_batch.rs
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@@ -103,6 +103,56 @@ impl RecordBatch {
RecordBatch { schema, columns }
}
+ /// Creates a new [`RecordBatch`] with no columns
+ ///
+ /// TODO add an code example using `append`
+ pub fn new() -> Self {
+ Self {
+ schema: Arc::new(Schema::empty()),
+ columns: Vec::new(),
+ }
+ }
+
+ /// Appends the `field_array` array to this `RecordBatch` as a
+ /// field named `field_name`.
+ ///
+ /// TODO: code example
+ ///
+ /// TODO: on error, can we return `Self` in some meaningful way?
+ pub fn append(self, field_name: &str, field_values: ArrayRef) ->
Result<Self> {
+ if let Some(col) = self.columns.get(0) {
+ if col.len() != field_values.len() {
+ return Err(ArrowError::InvalidArgumentError(
+ format!("all columns in a record batch must have the same
length. expected {}, field {} had {} ",
+ col.len(), field_name, field_values.len())
+ ));
+ }
+ }
+
+ let Self {
+ schema,
+ mut columns,
+ } = self;
+
+ // modify the schema we have if possible, otherwise copy
+ let mut schema = match Arc::try_unwrap(schema) {
+ Ok(schema) => schema,
+ Err(shared_schema) => shared_schema.as_ref().clone(),
+ };
+
+ let nullable = field_values.null_count() > 0;
Review comment:
I agree this would be an important point to clarify in the comments. If
you are creating more than one `RecordBatch` you should use the existing api to
create the `RecordBatch` from a `Schema` and `Vec<ArrayRef>`
If you are creating a single one then this is more convenient
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