## Coverage Report

#### Created: 2025-11-22 06:00

next uncovered line (L), next uncovered region (R), next uncovered branch (B)

    /Users/andrewlamb/Software/datafusion/datafusion/functions/src/core/expr_ext.rs

    Line
    Count
    Source
    1
    // Licensed to the Apache Software Foundation (ASF) under one
    2
    // or more contributor license agreements.  See the NOTICE file
    3
    // distributed with this work for additional information
    4
    // regarding copyright ownership.  The ASF licenses this file
    5
    // to you under the Apache License, Version 2.0 (the
    6
    // "License"); you may not use this file except in compliance
    7
    // with the License.  You may obtain a copy of the License at
    8
    //
    9
    //   http://www.apache.org/licenses/LICENSE-2.0
    10
    //
    11
    // Unless required by applicable law or agreed to in writing,
    12
    // software distributed under the License is distributed on an
    13
    // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    14
    // KIND, either express or implied.  See the License for the
    15
    // specific language governing permissions and limitations
    16
    // under the License.
    17
    18
    //! Extension methods for Expr.
    19
    20
    use datafusion_expr::{Expr, Literal};
    21
    22
    use super::expr_fn::get_field;
    23
    24
    /// Return access to the named field. Example `expr["name"]`
    25
    ///
    26
    /// ## Access field "my_field" from column "c1"
    27
    ///
    28
    /// For example if column "c1" holds documents like this
    29
    ///
    30
    /// ```json
    31
    /// {
    32
    ///   "my_field": 123.34,
    33
    ///   "other_field": "Boston",
    34
    /// }
    35
    /// ```
    36
    ///
    37
    /// You can access column "my_field" with
    38
    ///
    39
    /// ```
    40
    /// # use datafusion_expr::{col};
    41
    /// # use datafusion_functions::core::expr_ext::FieldAccessor;
    42
    /// let expr = col("c1").field("my_field");
    43
    /// assert_eq!(expr.schema_name().to_string(), "c1[my_field]");
    44
    /// ```
    45
    pub trait FieldAccessor {
    46
        fn field(self, name: impl Literal) -> Expr;
    47
    }
    48
    49
    impl FieldAccessor for Expr {
    50
    0
        fn field(self, name: impl Literal) -> Expr {
    51
    0
            get_field(self, name)
    52
    0
        }
    53
    }
    54
    55
    #[cfg(test)]
    56
    mod tests {
    57
        use super::*;
    58
    59
        use datafusion_expr::col;
    60
    61
        #[test]
    62
        fn test_field() {
    63
            let expr1 = col("a").field("b");
    64
            let expr2 = get_field(col("a"), "b");
    65
            assert_eq!(expr1, expr2);
    66
        }
    67
    }