Struct Config

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pub struct Config { /* private fields */ }

Expand description

Typed configuration document assembled from explicit sources.

Sources are explicit and merge in the order you choose. Later sources override earlier values, while nested objects merge recursively.

use nidus_config::Config;
use serde::Deserialize;

#[derive(Deserialize, Debug, PartialEq, Eq)]
struct Settings {
    port: u16,
    database: DatabaseSettings,
}

#[derive(Deserialize, Debug, PartialEq, Eq)]
struct DatabaseSettings {
    url: String,
    pool_size: u32,
}

let file = Config::from_json_str(r#"{
    "port": 3000,
    "database": { "url": "postgres://localhost/app", "pool_size": 5 }
}"#)?;

let env = Config::from_prefixed_vars("APP", [
    ("APP_PORT", "8080"),
    ("APP_DATABASE__POOL_SIZE", "10"),
]);

let settings: Settings = file.merge(env).deserialize()?;
assert_eq!(settings.port, 8080);
assert_eq!(settings.database.url, "postgres://localhost/app");
assert_eq!(settings.database.pool_size, 10);

Implementations§

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impl Config

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pub fn new() -> Self

Creates an empty configuration document.

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pub fn from_pairs<K, V>(pairs: impl IntoIterator<Item = (K, V)>) -> Self
where K: Into<String>, V: AsRef<str>,

Creates configuration from key/value pairs.

Values are parsed as JSON-like scalars, so strings such as "true", "42", and "null" become boolean, number, and null values.

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pub fn from_value(value: Value) -> Result<Self>

Creates configuration from a JSON object value.

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pub fn from_json_str(source: &str) -> Result<Self>

Creates configuration from a JSON object string.

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pub fn from_json_file(path: impl AsRef<Path>) -> Result<Self>

Creates configuration from a JSON object file.

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pub fn from_env_prefix(prefix: &str) -> Self

Creates configuration from process environment variables with a prefix.

For prefix APP, APP_PORT=3000 maps to port, and APP_DATABASE__URL=... maps to database.url.

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pub fn from_prefixed_vars<K, V>( prefix: &str, vars: impl IntoIterator<Item = (K, V)>, ) -> Self
where K: AsRef<str>, V: AsRef<str>,

Creates configuration from prefixed key/value variables.

This is useful for deterministic tests and for loading from custom environment sources. Prefix matching is case-sensitive; keys are normalized to lowercase after the prefix is removed. Double underscores create nested paths; empty path segments are ignored.

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pub fn insert_value(&mut self, key: impl Into<String>, value: Value)

Inserts a raw JSON configuration value.

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pub fn get(&self, key: &str) -> Option<&Value>

Returns a top-level raw configuration value.

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pub fn get_typed<T>(&self, key: &str) -> Result<Option<T>>
where T: DeserializeOwned,

Deserializes a top-level configuration value into a typed value.

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pub fn get_required_typed<T>(&self, key: &str) -> Result<T>
where T: DeserializeOwned,

Deserializes a required top-level configuration value into a typed value.

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pub fn get_path<I, S>(&self, path: I) -> Option<&Value>
where I: IntoIterator<Item = S>, S: AsRef<str>,

Returns a nested raw configuration value by path.

Object segments match keys. Array segments are zero-based numeric indexes such as "0".

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pub fn get_path_typed<I, S, T>(&self, path: I) -> Result<Option<T>>
where I: IntoIterator<Item = S>, S: AsRef<str>, T: DeserializeOwned,

Deserializes a nested configuration value into a typed value.

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pub fn get_required_path_typed<I, S, T>(&self, path: I) -> Result<T>
where I: IntoIterator<Item = S>, S: AsRef<str>, T: DeserializeOwned,

Deserializes a required nested configuration value into a typed value.

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pub fn merge(self, other: Self) -> Self

Merges another configuration source into this one.

Values from other take precedence. Nested objects are merged recursively so later sources can override one field without replacing an entire nested configuration section.

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