Crate de_env

de_env

Deserialize environment variables into a struct.

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Example

Assuming we have a TIMEOUT and HOST environment variable:

#[derive(serde::Deserialize, Debug)]
#[serde(rename_all = "SCREAMING_SNAKE_CASE")]
struct Config {
    timeout: u16,
    host: std::net::IpAddr,
}

let config: Config = de_env::from_env()?;

println!("{config:#?}");

Supported Primitives

• String slices
• Chars
• Numbers (parsed with their respective FromStr implementations)
• Booleans (see boolean parsing)

Boolean Parsing

Boolean parsing is case-insensitive.

If the truthy-falsy feature is enabled (default):

• Truthy values:
  • true or its shorthand t
  • yes or its shorthand y
  • on
  • 1
• Falsy values:
  • false or its shorthand f
  • no or its shorthand n
  • off
  • 0

If the truthy-falsy feature is disabled, only true and false are considered valid booleans.

Enums

Only unit variants can be deserialized.

Assuming we have a LOG_LEVEL environment variable set to INFO or WARN:

#[derive(serde::Deserialize, Debug)]
#[serde(rename_all = "SCREAMING_SNAKE_CASE")]
enum Level {
    Info,
    Warn
}

#[derive(serde::Deserialize, Debug)]
#[serde(rename_all = "SCREAMING_SNAKE_CASE")]
struct Config {
    log_level: Level,
}

let config: Config = de_env::from_env()?;

println!("{config:#?}");

Unsupported Types

The goal of this crate is to deserialize environment variables into a struct, no other type is supported at top level. Custom types must be able to deserialize from supported primitives.

Structs

Error

Represent an error that may arise when deserializing.

Functions

from_env

Deserialize an instance of T from the environment variables of the current process.

from_env_prefixed

Deserialize an instance of T from the environment variables of the current process with the specified prefix.

from_iter

Deserialize an instance of T from an iterator of key-value tuple.

Type Definitions

Result

Convenience alias for a Result with this crate Error type.