Struct Project 

pub struct Project {
    pub expr: ExpressionRef,
    pub schema: SchemaRef,
}

Available on crate feature declarative-plans only.

Projects the input through expr into rows of schema.

expr must be a struct constructor or struct patch whose fields match schema. It is evaluated with schema as its output struct type: the struct’s fields are the output columns, schema supplies names and nullability, and any type or arity mismatch is an error. Downstream nodes see the logical field names declared in schema.

A struct patch carries the input struct through field by field, naming only the columns that change – replacing or dropping existing fields and injecting new ones – while everything else passes through unchanged, so it costs O(changes) rather than O(schema width). The patched result still covers every field in schema.

Example

Input { id, first, last, add: { path, size, stats_parsed: { numRecords } } } projected to { id, names, file_meta }, showing passthrough, array construction, nested input access, and a struct output column:

Project {
    expr: Expression::struct_from([
        col!("id"),
        Expression::array([col!("first"), col!("last")]),
        Expression::struct_from([
            col!("add.path"),
            col!("add.size"),
            col!("add.stats_parsed.numRecords"),
        ]),
    ]),
    schema: {
        id: int,
        names: array<string>,
        file_meta: { path: string, size: long, num_records: long },
    },
}

Fields

expr: ExpressionRef

schema: SchemaRef

Trait Implementations

impl Clone for Project

fn clone(&self) -> Project

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Project

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<&Project> for ProjectNode

fn from(node: &Project) -> Self

Converts to this type from the input type.

impl From<Project> for Operator

fn from(payload: Project) -> Self

Converts to this type from the input type.