tustvold commented on code in PR #3992:
URL: https://github.com/apache/arrow-rs/pull/3992#discussion_r1154695447
##########
arrow-schema/src/field.rs:
##########
@@ -145,6 +147,104 @@ impl Field {
}
}
+ /// Create a new [`Field`] with [`DataType::Dictionary`]
+ ///
+ /// Use [`Self::new_dict`] for more advanced dictionary options
+ pub fn new_dictionary(
+ name: impl Into<String>,
+ key: DataType,
+ value: DataType,
+ nullable: bool,
+ ) -> Self {
+ // TODO: Should this enforce `key` is a dictionary key type
+ let data_type = DataType::Dictionary(Box::new(key), Box::new(value));
+ Self::new(name, data_type, nullable)
+ }
+
+ /// Create a new [`Field`] with [`DataType::Struct`]
+ pub fn new_struct(
+ name: impl Into<String>,
+ fields: impl Into<Fields>,
+ nullable: bool,
+ ) -> Self {
+ Self::new(name, DataType::Struct(fields.into()), nullable)
+ }
+
+ /// Create a new [`Field`] with [`DataType::List`]
+ ///
+ /// - `name`: the name of the [`DataType::List`] field
+ /// - `value`: the list elements
+ /// - `nullable`: if the [`DataType::List`] array is nullable
+ ///
+ /// Uses "item" as the name of the child field, this can be overridden
with [`Self::new`]
+ pub fn new_list(
+ name: impl Into<String>,
+ value: impl Into<FieldRef>,
+ nullable: bool,
+ ) -> Self {
+ Self::new(name, DataType::List(value.into()), nullable)
+ }
+
+ /// Create a new [`Field`] with [`DataType::LargeList`]
+ ///
+ /// - `name`: the name of the [`DataType::LargeList`] field
+ /// - `value`: the list elements
+ /// - `nullable`: if the [`DataType::LargeList`] array is nullable
+ pub fn new_large_list(
+ name: impl Into<String>,
+ value: impl Into<FieldRef>,
+ nullable: bool,
+ ) -> Self {
+ Self::new(name, DataType::LargeList(value.into()), nullable)
+ }
+
+ /// Create a new [`Field`] with [`DataType::Map`]
+ ///
+ /// - `name`: the name of the [`DataType::Map`] field
+ /// - `entries`: the name of the inner [`DataType::Struct`] field
+ /// - `keys`: the map keys
+ /// - `values`: the map values
+ /// - `sorted`: if the [`DataType::Map`] array is sorted
+ /// - `nullable`: if the [`DataType::Map`] array is nullable
+ pub fn new_map(
+ name: impl Into<String>,
+ entries: impl Into<String>,
+ keys: impl Into<FieldRef>,
+ values: impl Into<FieldRef>,
+ sorted: bool,
+ nullable: bool,
+ ) -> Self {
+ let data_type = DataType::Map(
+ Arc::new(Field::new(
+ entries.into(),
+ DataType::Struct(Fields::from([keys.into(), values.into()])),
+ false, // The inner map field is always non-nullable (#1697),
+ )),
+ sorted,
+ );
+ Self::new(name, data_type, nullable)
+ }
+
+ /// Create a new [`Field`] with [`DataType::Union`]
+ ///
+ /// - `name`: the name of the [`DataType::Map`] field
+ /// - `type_ids`: the union type ids
+ /// - `fields`: the union fields
+ /// - `mode`: the union mode
+ pub fn new_union<S, F, T>(name: S, type_ids: T, fields: F, mode:
UnionMode) -> Self
+ where
+ S: Into<String>,
+ F: IntoIterator,
+ F::Item: Into<FieldRef>,
+ T: IntoIterator<Item = i8>,
+ {
+ Self::new(
+ name,
+ DataType::Union(UnionFields::new(type_ids, fields), mode),
+ false, // Unions cannot be nullable
Review Comment:
This is potentially worth highlighting, these constructors allow us to help
ensure schema invariants
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