datafusion_functions_nested/
map_entries.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
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5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
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8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
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14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18//! [`ScalarUDFImpl`] definitions for map_entries function.
19
20use crate::utils::{get_map_entry_field, make_scalar_function};
21use arrow::array::{Array, ArrayRef, ListArray};
22use arrow::datatypes::{DataType, Field, Fields};
23use datafusion_common::utils::take_function_args;
24use datafusion_common::{Result, cast::as_map_array, exec_err};
25use datafusion_expr::{
26    ArrayFunctionSignature, ColumnarValue, Documentation, ScalarFunctionArgs,
27    ScalarUDFImpl, Signature, TypeSignature, Volatility,
28};
29use datafusion_macros::user_doc;
30use std::sync::Arc;
31
32make_udf_expr_and_func!(
33    MapEntriesFunc,
34    map_entries,
35    map,
36    "Return a list of all entries in the map.",
37    map_entries_udf
38);
39
40#[user_doc(
41    doc_section(label = "Map Functions"),
42    description = "Returns a list of all entries in the map.",
43    syntax_example = "map_entries(map)",
44    sql_example = r#"```sql
45SELECT map_entries(MAP {'a': 1, 'b': NULL, 'c': 3});
46----
47[{'key': a, 'value': 1}, {'key': b, 'value': NULL}, {'key': c, 'value': 3}]
48
49SELECT map_entries(map([100, 5], [42, 43]));
50----
51[{'key': 100, 'value': 42}, {'key': 5, 'value': 43}]
52```"#,
53    argument(
54        name = "map",
55        description = "Map expression. Can be a constant, column, or function, and any combination of map operators."
56    )
57)]
58#[derive(Debug, PartialEq, Eq, Hash)]
59pub struct MapEntriesFunc {
60    signature: Signature,
61}
62
63impl Default for MapEntriesFunc {
64    fn default() -> Self {
65        Self::new()
66    }
67}
68
69impl MapEntriesFunc {
70    pub fn new() -> Self {
71        Self {
72            signature: Signature::new(
73                TypeSignature::ArraySignature(ArrayFunctionSignature::MapArray),
74                Volatility::Immutable,
75            ),
76        }
77    }
78}
79
80impl ScalarUDFImpl for MapEntriesFunc {
81    fn name(&self) -> &str {
82        "map_entries"
83    }
84
85    fn signature(&self) -> &Signature {
86        &self.signature
87    }
88
89    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
90        let [map_type] = take_function_args(self.name(), arg_types)?;
91        let map_fields = get_map_entry_field(map_type)?;
92        Ok(DataType::List(Arc::new(Field::new_list_field(
93            DataType::Struct(Fields::from(vec![
94                Field::new(
95                    "key",
96                    map_fields.first().unwrap().data_type().clone(),
97                    false,
98                ),
99                Field::new(
100                    "value",
101                    map_fields.get(1).unwrap().data_type().clone(),
102                    true,
103                ),
104            ])),
105            false,
106        ))))
107    }
108
109    fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
110        make_scalar_function(map_entries_inner)(&args.args)
111    }
112
113    fn documentation(&self) -> Option<&Documentation> {
114        self.doc()
115    }
116}
117
118fn map_entries_inner(args: &[ArrayRef]) -> Result<ArrayRef> {
119    let [map_arg] = take_function_args("map_entries", args)?;
120
121    let map_array = match map_arg.data_type() {
122        DataType::Map(_, _) => as_map_array(&map_arg)?,
123        _ => return exec_err!("Argument for map_entries should be a map"),
124    };
125
126    Ok(Arc::new(ListArray::new(
127        Arc::new(Field::new_list_field(
128            DataType::Struct(Fields::from(vec![
129                Field::new("key", map_array.key_type().clone(), false),
130                Field::new("value", map_array.value_type().clone(), true),
131            ])),
132            false,
133        )),
134        map_array.offsets().clone(),
135        Arc::new(map_array.entries().clone()),
136        map_array.nulls().cloned(),
137    )))
138}
datafusion_functions_nested/map_entries.rs

datafusion_functions_nested/
map_entries.rs
