Function mmap_json_file::distinct_of_field

pub fn distinct_of_field<'a, T: 'static, F>(
    f: String, 
    filter: F, 
    o: String
) -> Result<i32> where
    T: DeserializeOwned + Debug + Clone + Send + Serialize,
    F: Fn(T) -> String, 

Disctinct values of the contents of a json field.

• f Filename and full accesislbe path of the input json file
• filter A closure that can handle an input parameter of type T and provide the field with distincts.
• o Filename and full accesislbe path of the output json file.

Input types

• T The type of the structure.
• F Closure template with input function type.

Return

• count No of distinct records found.

Example usage

use mmap_json_file;
use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize, Debug, Clone, Default)]
struct TestSimple {
    a: Option<String>,
    c: Option<String>,
}

#[derive(Serialize, Deserialize, Debug, Clone, Default)]
struct TestSimpleNested {
    b: Option<TestSimple>,
    c: Option<String>,
}

#[derive(Serialize, Deserialize, Debug, Clone, Default)]
struct TestSimpleCompound {
    a: Option<TestSimpleNested>,
    f: Option<String>,
}

let filter = |record: TestSimple| -> String { record.a.unwrap() };

let _res = mmap_json_file::distinct_of_field::<
    TestSimple,
   Box<dyn Fn(TestSimple) -> String>,
>("data/test_simple.json".to_string(), Box::new(filter), "output".to_string());