Function count_with_filter

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

Count the contents of a json file with filter specified.

Arguments

• f Filename and full accesislbe path of the input json file
• filter A closure that can handle an input parameter of type T.

Return

• count No of records that match the filter.

Input types

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

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| -> bool { record.a.unwrap() == "b" };

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