risingwave_expr_impl/scalar/
array_to_string.rs

1// Copyright 2025 RisingWave Labs
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#![allow(clippy::unit_arg)]
16
17use std::fmt::Write;
18
19use risingwave_common::array::*;
20use risingwave_common::types::ToText;
21use risingwave_expr::expr::Context;
22use risingwave_expr::function;
23
24/// Converts each array element to its text representation, and concatenates those
25/// separated by the delimiter string. If `null_string` is given and is not NULL,
26/// then NULL array entries are represented by that string; otherwise, they are omitted.
27///
28/// ```sql
29/// array_to_string ( array anyarray, delimiter text [, null_string text ] ) → text
30/// ```
31///
32/// Examples:
33///
34/// ```slt
35/// query T
36/// select array_to_string(array[1, 2, 3, NULL, 5], ',')
37/// ----
38/// 1,2,3,5
39///
40/// query T
41/// select array_to_string(array[1, 2, 3, NULL, 5], ',', '*')
42/// ----
43/// 1,2,3,*,5
44///
45/// query T
46/// select array_to_string(array[null,'foo',null], ',', '*');
47/// ----
48/// *,foo,*
49///
50/// query T
51/// select array_to_string(array['2023-02-20 17:35:25'::timestamp, null,'2023-02-19 13:01:30'::timestamp], ',', '*');
52/// ----
53/// 2023-02-20 17:35:25,*,2023-02-19 13:01:30
54///
55/// query T
56/// with t as (
57///   select array[1,null,2,3] as arr, ',' as d union all
58///   select array[4,5,6,null,7] as arr, '|')
59/// select array_to_string(arr, d) from t;
60/// ----
61/// 1,2,3
62/// 4|5|6|7
63///
64/// # `array` or `delimiter` are required. Otherwise, returns null.
65/// query T
66/// select array_to_string(array[1,2], NULL);
67/// ----
68/// NULL
69///
70/// query error polymorphic type
71/// select array_to_string(null, ',');
72///
73/// # multidimensional array
74/// query T
75/// select array_to_string(array[array['one', null], array['three', 'four']]::text[][], ',');
76/// ----
77/// one,three,four
78///
79/// query T
80/// select array_to_string(array[array['one', null], array['three', 'four']]::text[][], ',', '*');
81/// ----
82/// one,*,three,four
83/// ```
84#[function("array_to_string(anyarray, varchar) -> varchar")]
85fn array_to_string(array: ListRef<'_>, delimiter: &str, ctx: &Context, writer: &mut impl Write) {
86    let element_data_type = ctx.arg_types[0].unnest_list();
87    let mut first = true;
88    for element in array.flatten().iter() {
89        let Some(element) = element else { continue };
90        if !first {
91            write!(writer, "{}", delimiter).unwrap();
92        } else {
93            first = false;
94        }
95        element.write_with_type(element_data_type, writer).unwrap();
96    }
97}
98
99#[function("array_to_string(anyarray, varchar, varchar) -> varchar")]
100fn array_to_string_with_null(
101    array: ListRef<'_>,
102    delimiter: &str,
103    null_string: &str,
104    ctx: &Context,
105    writer: &mut impl Write,
106) {
107    let element_data_type = ctx.arg_types[0].unnest_list();
108    let mut first = true;
109    for element in array.flatten().iter() {
110        if !first {
111            write!(writer, "{}", delimiter).unwrap();
112        } else {
113            first = false;
114        }
115        match element {
116            Some(s) => s.write_with_type(element_data_type, writer).unwrap(),
117            None => write!(writer, "{}", null_string).unwrap(),
118        }
119    }
120}
risingwave_expr_impl/scalar/array_to_string.rs

risingwave_expr_impl/scalar/
array_to_string.rs
