Method try_new

arrow-array/src/array/union_array.rs:177–242

Attempts to create a new `UnionArray`, validating the inputs provided. The order of child arrays child array order must match the fields order

(
        fields: UnionFields,
        type_ids: ScalarBuffer<i8>,
        offsets: Option<ScalarBuffer<i32>>,
        children: Vec<ArrayRef>,
    )

    ///
    /// The order of child arrays child array order must match the fields order
    pub fn try_new(
        fields: UnionFields,
        type_ids: ScalarBuffer<i8>,
        offsets: Option<ScalarBuffer<i32>>,
        children: Vec<ArrayRef>,
    ) -> Result<Self, ArrowError> {
        // There must be a child array for every field.
        if fields.len() != children.len() {
            return Err(ArrowError::InvalidArgumentError(
                "Union fields length must match child arrays length".to_string(),
            ));
        }

        if let Some(offsets) = &offsets {
            // There must be an offset value for every type id value.
            if offsets.len() != type_ids.len() {
                return Err(ArrowError::InvalidArgumentError(
                    "Type Ids and Offsets lengths must match".to_string(),
                ));
            }
        } else {
            // Sparse union child arrays must be equal in length to the length of the union
            for child in &children {
                if child.len() != type_ids.len() {
                    return Err(ArrowError::InvalidArgumentError(
                        "Sparse union child arrays must be equal in length to the length of the union".to_string(),
                    ));
                }
            }
        }

        // Create mapping from type id to array lengths.
        let max_id = fields.iter().map(|(i, _)| i).max().unwrap_or_default() as usize;
        let mut array_lens = vec![i32::MIN; max_id + 1];
        for (cd, (field_id, _)) in children.iter().zip(fields.iter()) {
            array_lens[field_id as usize] = cd.len() as i32;
        }

        // Type id values must match one of the fields.
        for id in &type_ids {
            match array_lens.get(*id as usize) {
                Some(x) if *x != i32::MIN => {}
                _ => {
                    return Err(ArrowError::InvalidArgumentError(
                        "Type Ids values must match one of the field type ids".to_owned(),
                    ));
                }
            }
        }

        // Check the value offsets are in bounds.
        if let Some(offsets) = &offsets {
            let mut iter = type_ids.iter().zip(offsets.iter());
            if iter.any(|(type_id, &offset)| offset < 0 || offset >= array_lens[*type_id as usize])
            {
                return Err(ArrowError::InvalidArgumentError(
                    "Offsets must be non-negative and within the length of the Array".to_owned(),
                ));