Padding

The AST Builder API in GlueSQL allows you to execute lpad and rpad functions for text padding.

lpad

lpad returns the string with leading space if the length of the string is less than the specified length.

lpad<'a, T: Into<ExprNode<'a>>>(expr: T, len: usize, fill: Option<String>) -> ExprNode<'a>

rpad

rpad returns the string with trailing space if the length of the string is less than the specified length.

rpad<'a, T: Into<ExprNode<'a>>>(expr: T, len: usize, fill: Option<String>) -> ExprNode<'a>

Examples

In these examples, the LPAD and RPAD functions should return matching values.

use {
    crate::*,
    gluesql_core::{
        ast_builder::{function as f, *},
        prelude::Value::{Null, Str},
    },
};

test_case!(padding, {
    let glue = get_glue!();

    let actual = values(vec![
        vec![f::lpad("'hello'", 10, None), f::rpad("'hello'", 10, None)],
        vec![
            f::lpad("'hello'", 10, Some("'ab'".into())),
            f::rpad("'hello'", 10, Some("'ab'".into())),
        ],
        vec![f::lpad("'hello'", 3, None), f::rpad("'hello'", 3, None)],
        vec![
            f::lpad("'hello'", 3, Some("'ab'".into())),
            f::rpad("'hello'", 3, Some("'ab'".into())),
        ],
        vec![f::lpad("NULL", 5, None), f::rpad("NULL", 5, None)],
    ])
    .alias_as("Sub")
    .select()
    .project("column1 AS lpaded")
    .project("column2 AS rpaded")
    .execute(glue)
    .await;
    let expected = Ok(select_with_null!(
        lpaded                       | rpaded;
        Str("     hello".to_owned())   Str("hello     ".to_owned());
        Str("ababahello".to_owned())   Str("helloababa".to_owned());
        Str("hel".to_owned())          Str("hel".to_owned());
        Str("hel".to_owned())          Str("hel".to_owned());
        Null                           Null
    ));
    assert_eq!(
        actual, expected,
        "lpad and rpad should pad the string with given length"
    );
});

| lpaded       | rpaded       |
| ------------ | ------------ |
| '     hello' | 'hello     ' |
| 'ababahello' | 'helloababa' |
| 'hel'        | 'hel'        |
| 'hel'        | 'hel'        |
| Null         | Null         |