Configuration Binding

The preferred way to read related configuration values is using the options pattern. For example, to read the following configuration values:

{
  "Position": {
    "Title": "Editor",
    "Name": "Joe Smith"
  }
}

Create the following PositionOptions struct:

#[derive(Default)]
pub struct PositionOptions {
    pub title: String,
    pub name: String,
}

An options struct:

• must be public.
• should implement the Default trait; otherwise a custom OptionsFactory is required.
• binds public read-write fields.

The following code:

• calls ConfigurationBinder::bind to bind the PositionOptions class to the "Position" section.
• displays the Position configuration data.
• requires the binder feature to be enabled
  • which transitively enables the serde feature

use config::*;

#[derive(Default, Deserialize)]
#[serde(rename_all(deserialize = "PascalCase"))]
pub struct PositionOptions {
    pub title: String,
    pub name: String,
}

pub TestModel<'a> {
    config: &'a dyn Configuration
}

impl<'a> TestModel<'a> {
    pub new(config: &dyn Configuration) -> Self {
        Self { config }
    }

    pub get(&self) -> String {
        let mut options = PositionOptions::default();
        let section = self.config.section("Position").bind(&mut options);
        format!("Title: {}\nName: {}", options.title, options.name)
    }
}

ConfigurationBinder::reify binds and returns the specified type. ConfigurationBinder::reify may be more convenient than using ConfigurationBinder::bind. The following code shows how to use ConfigurationBinder::reify with the PositionOptions struct:

use config::*;

pub TestModel<'a> {
    config: &'a dyn Configuration
}

impl<'a> TestModel<'a> {
    pub new(config: &dyn Configuration) -> Self {
        Self { config }
    }

    pub get(&self) -> String {
        let options: PositionOptions = self.config.section("Position").reify();
        format!("Title: {}\nName: {}", options.title, options.name)
    }
}