Struct ColumnCountConstraint 

pub struct ColumnCountConstraint { /* private fields */ }

A constraint that validates the number of columns in a dataset.

This constraint checks if the column count of the dataset meets the specified assertion. It uses DataFusion’s schema to determine the number of columns.

Examples

use term_guard::constraints::{Assertion, ColumnCountConstraint};
use term_guard::core::Constraint;

// Check for exactly 15 columns
let constraint = ColumnCountConstraint::new(Assertion::Equals(15.0));
assert_eq!(constraint.name(), "column_count");

// Check for at least 10 columns
let constraint = ColumnCountConstraint::new(Assertion::GreaterThanOrEqual(10.0));

Implementations

impl ColumnCountConstraint

pub fn new(assertion: Assertion) -> Self

Creates a new column count constraint.

Arguments

• assertion - The assertion to apply to the column count

Trait Implementations

impl Clone for ColumnCountConstraint

fn clone(&self) -> ColumnCountConstraint

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Constraint for ColumnCountConstraint

fn evaluate<'life0, 'life1, 'async_trait>( &'life0 self, ctx: &'life1 SessionContext, ) -> Pin<Box<dyn Future<Output = Result<ConstraintResult>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Evaluates the constraint against the data in the session context.

fn name(&self) -> &str

Returns the name of the constraint.

fn column(&self) -> Option<&str>

Returns the column this constraint operates on (if single-column).

fn metadata(&self) -> ConstraintMetadata

Returns the metadata associated with this constraint.

fn description(&self) -> Option<&str>

Returns a description of what this constraint validates.

impl Debug for ColumnCountConstraint

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

Formats the value using the given formatter.