kosiew commented on code in PR #16583:
URL: https://github.com/apache/datafusion/pull/16583#discussion_r2181718449
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datafusion/core/src/datasource/listing/table.rs:
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@@ -123,25 +176,72 @@ impl ListingTableConfig {
///
/// If the schema is provided, it must contain only the fields in the file
/// without the table partitioning columns.
+ ///
+ /// # Example: Specifying Table Schema
+ /// ```rust
+ /// # use std::sync::Arc;
+ /// # use datafusion::datasource::listing::{ListingTableConfig,
ListingOptions, ListingTableUrl};
+ /// # use datafusion::datasource::file_format::parquet::ParquetFormat;
+ /// # use arrow::datatypes::{Schema, Field, DataType};
+ /// # let table_paths =
ListingTableUrl::parse("file:///path/to/data").unwrap();
+ /// # let listing_options =
ListingOptions::new(Arc::new(ParquetFormat::default()));
+ /// let schema = Arc::new(Schema::new(vec![
+ /// Field::new("id", DataType::Int64, false),
+ /// Field::new("name", DataType::Utf8, true),
+ /// ]));
+ ///
+ /// let config = ListingTableConfig::new(table_paths)
+ /// .with_listing_options(listing_options) // Set options first
+ /// .with_schema(schema); // Then set schema
+ /// ```
pub fn with_schema(self, schema: SchemaRef) -> Self {
+ // Note: We preserve existing options state, but downstream code may
expect
+ // options to be set. Consider calling with_listing_options() or
infer_options()
+ // before operations that require options to be present.
+ debug_assert!(
+ self.options.is_some() || cfg!(test),
+ "ListingTableConfig::with_schema called without options set. \
+ Consider calling with_listing_options() or infer_options() first
to avoid panics in downstream code."
+ );
+
Self {
- table_paths: self.table_paths,
file_schema: Some(schema),
- options: self.options,
schema_source: SchemaSource::Specified,
+ ..self
Review Comment:
with_schema is required so that SchemaAdapter knows which target schema to
adapt to.
I added debug_assert to ensure future changes do not unwittingly change
self.options to be None.
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