Crates.io | env-settings |
lib.rs | env-settings |
version | 0.1.11 |
source | src |
created_at | 2023-07-29 13:23:33.695301 |
updated_at | 2024-02-20 11:52:50.687209 |
description | Initialize Rust structs using environment variables (like `pydantic`'s `BaseSettings`) |
homepage | https://github.com/dariocurr/env-settings |
repository | https://github.com/dariocurr/env-settings |
max_upload_size | |
id | 929248 |
size | 13,057 |
Env Settings is a Rust library that helps you to initialize structs using environment variables
This Rust library took inspiration from
pydantic's BaseSettings
Python class
cargo add env-settings env-settings-derive env-settings-utils
When you add the EnvSettings
derive to a struct
, two public methods are added to it
fn from_env(...) -> env_settings_utils::EnvSettingsResult<Self>
Create a new instance using just the environment variables. Skipped fields must be passed. If something fails, it returns an env_settings_utils::EnvSettingsError
error
fn new(...) -> env_settings_utils::EnvSettingsResult<Self>
Create a new instance using a combination of environment variables and parameters. More in detail, every field that can be initialized by the environment variables can be passed as parameter wrapped in an Option
object. Then if the parameter is Some
, it is used, otherwise the value is recoved from the environment variables. Skipped fields must be passed. If something fails, it returns an env_settings_utils::EnvSettingsError
error
export name=paolo
export favourite_number=42
use env_settings_derive::EnvSettings;
#[derive(EnvSettings)]
struct MyStruct {
name: String,
favourite_number: u8,
}
fn main() {
let my_struct = MyStruct::from_env().unwrap();
assert_eq!(my_struct.name, "paolo".to_string());
assert_eq!(my_struct.favourite_number, 42);
let name = "luca";
let my_struct = MyStruct::new(Some(name.to_string()), None).unwrap();
assert_eq!(my_struct.name, name);
assert_eq!(my_struct.favourite_number, 42);
}
echo "MY_STRUCT_FAVOURITE_NUMBER=42\n" > .env
export MY_BIRTH_DATE=01/01/1970
use env_settings_derive::EnvSettings;
#[derive(EnvSettings)]
#[env_settings(case_insensitive, file_path = ".env", prefix="MY_STRUCT_")]
struct MyStruct {
#[env_settings(default = "paolo")]
name: String,
favourite_number: u8,
#[env_settings(variable = "MY_BIRTH_DATE")]
birth_date: String,
birth_place: Option<String>,
#[env_settings(skip)]
friends: Vec<String>,
}
fn main() {
let friends = vec!["luca".to_string()];
let my_struct = MyStruct::from_env(friends.clone()).unwrap();
assert_eq!(my_struct.name, "paolo".to_string());
assert_eq!(my_struct.favourite_number, 42);
assert_eq!(my_struct.birth_date, "01/01/1970");
assert_eq!(my_struct.birth_place, None);
assert_eq!(my_struct.friends, friends);
let name = "luca";
let my_struct = MyStruct::new(
Some(name.to_string()),
None,
None,
Some("london".to_string()),
friends.clone(),
).unwrap();
assert_eq!(my_struct.name, name);
assert_eq!(my_struct.favourite_number, 42);
assert_eq!(my_struct.birth_date, "01/01/1970");
assert_eq!(my_struct.birth_place, Some("london".to_string()));
assert_eq!(my_struct.friends, friends);
}
The current supported parameters for the structs are:
case_insensitive
: whether the environment variables matching should be case insensitive. By default, matching is case sensitive.delay
: whether to delay the lookup for environment variables from compilation time to run time. By default the lookup is performed at compilation timefile_path
: the file path to read to add some environment variables (e.g. .env
). By default, it is not setprefix
: the prefix to add to the name of the struct fields before matching the environment variables. By default, it is not setThe current supported parameters for the fields are:
default
: the default value to use if the environment variable is not found. By default, it is not setskip
: whether to skip the parsing of the environment variable. It is necessary if the type specified does not implement std::str::FromStr
.variable
: the environment variable to use for the lookup. By default, the name of the fieldnew
method (if using new
)..env
)Before starting to work on a contribution please read:
When testing run:
cargo test -- --test-threads=1
to prevent tests from competitively interacting with the same file
This project is licensed under the terms of the MIT or Apache 2.0 license.