use crate::validators::{ValidationReport, ValidationResult, Validator};
use polars::prelude::*;
pub struct MaxLengthValidator {
pub value: usize,
}
impl Validator for MaxLengthValidator {
fn name(&self) -> &'static str {
"MaxLength"
}
fn validate(&self, df: &DataFrame, column_name: &str) -> ValidationResult<ValidationReport> {
let series = df.column(column_name)?;
if let Ok(ca) = series.str() {
let lengths = ca.str_len_chars();
let mask = lengths.gt(self.value as u32);
let bad_count = mask.sum().unwrap_or(0);
if bad_count > 0 {
Ok(ValidationReport {
status: "fail",
details: Some(format!(
"bad_count={}, max_length={}",
bad_count, self.value
)),
})
} else {
Ok(ValidationReport {
status: "pass",
details: None,
})
}
} else {
Ok(ValidationReport {
status: "skipped",
details: Some("column is not a string type".to_string()),
})
}
}
}
#[cfg(test)]
mod tests {
use super::*;
fn make_str_df(values: &[Option<&str>]) -> DataFrame {
let s = Series::new("col".into(), values.to_vec());
DataFrame::new(vec![s.into()]).unwrap()
}
#[test]
fn passes_when_all_values_within_limit() {
let df = make_str_df(&[Some("a"), Some("bb"), Some("ccc")]);
let validator = MaxLengthValidator { value: 3 };
let report = validator.validate(&df, "col").unwrap();
assert_eq!(report.status, "pass");
assert!(report.details.is_none());
}
#[test]
fn fails_when_values_exceed_limit() {
let df = make_str_df(&[Some("abcd"), Some("bb"), Some("ccc")]);
let validator = MaxLengthValidator { value: 3 };
let report = validator.validate(&df, "col").unwrap();
assert_eq!(report.status, "fail");
assert!(report.details.unwrap().contains("bad_count=1"));
}
#[test]
fn ignores_null_values() {
let df = make_str_df(&[Some("ok"), None, Some("fine")]);
let validator = MaxLengthValidator { value: 4 };
let report = validator.validate(&df, "col").unwrap();
assert_eq!(report.status, "pass");
}
#[test]
fn passes_on_empty_column() {
let s: Series = Series::new("col".into(), Vec::<Option<&str>>::new());
let df = DataFrame::new(vec![s.into()]).unwrap();
let validator = MaxLengthValidator { value: 5 };
let report = validator.validate(&df, "col").unwrap();
assert_eq!(report.status, "pass");
}
#[test]
fn skips_on_non_string_column() {
let s = Series::new("col".into(), &[1, 2, 3]);
let df = DataFrame::new(vec![s.into()]).unwrap();
let validator = MaxLengthValidator { value: 2 };
let report = validator.validate(&df, "col").unwrap();
assert_eq!(report.status, "skipped");
assert!(report.details.unwrap().contains("not a string"));
}
}