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use anyhow::{anyhow, Result};
use log::{debug, warn};
use serde::de::DeserializeOwned;
use serde::Serialize;
use serde_bridge::{into_value, FromValue};
use crate::collectors::{Collector, IntoCollector};
use crate::value::{merge, merge_with_default};
/// Builder will collect values from different collectors and merge into the final value.
#[derive(Default)]
pub struct Builder<V: DeserializeOwned + Serialize> {
collectors: Vec<Box<dyn Collector<V>>>,
}
impl<V> Builder<V>
where
V: DeserializeOwned + Serialize,
{
/// Create new builders.
pub fn new() -> Builder<V> {
Self {
collectors: Vec::new(),
}
}
/// Add collectors into builder.
///
/// This is a lazy operation that no real IO happens.
///
/// # Example
///
/// ```
/// use serde::{Deserialize, Serialize};
/// use serfig::collectors::{from_env, from_file, from_self};
/// use serfig::parsers::Toml;
/// use serfig::Builder;
///
/// #[derive(Debug, Serialize, Deserialize, PartialEq, Default)]
/// #[serde(default)]
/// struct TestConfig {
/// a: String,
/// b: String,
/// c: i64,
/// }
///
/// fn main() -> anyhow::Result<()> {
/// let builder = Builder::default()
/// .collect(from_env())
/// .collect(from_file(Toml, "config.toml"))
/// .collect(from_self(TestConfig::default()));
///
/// Ok(())
/// }
/// ```
pub fn collect(mut self, c: impl IntoCollector<V>) -> Self {
self.collectors.push(c.into_collector());
Self {
collectors: self.collectors,
}
}
/// Use input `default` as the default value to build.
///
/// # Behavior
///
/// Builder will ignore any errors happened during build, and only returns
/// errors if no valid value collected.
///
/// # Example
///
/// ```
/// use serde::{Deserialize, Serialize};
/// use serfig::collectors::{from_env, from_file, from_self};
/// use serfig::parsers::Toml;
/// use serfig::Builder;
///
/// #[derive(Debug, Serialize, Deserialize, PartialEq, Default)]
/// #[serde(default)]
/// struct TestConfig {
/// a: String,
/// b: String,
/// c: i64,
/// }
///
/// fn main() -> anyhow::Result<()> {
/// let builder = Builder::default()
/// .collect(from_env());
///
/// let t = builder.build_with(TestConfig::default())?;
/// Ok(())
/// }
/// ```
pub fn build_with(self, default: V) -> Result<V> {
let mut result = None;
let default = into_value(default)?;
let mut value = default.clone();
for mut c in self.collectors {
// Merge will default to make sure every value here is from
// user input.
let collected_value = merge_with_default(default.clone(), c.collect()?);
// Three way merge here to make sure we take the last non-default
// value.
value = merge(default.clone(), value, collected_value);
debug!("got value: {:?}", value);
// Re-deserialize the value if we from_value correctly.
result = match V::from_value(value.clone()) {
Ok(v) => Some(v),
Err(e) => {
warn!("deserialize value {:?}: {:?}", value, e);
continue;
}
}
}
result.ok_or_else(|| anyhow!("no valid value to deserialize",))
}
}
impl<V> Builder<V>
where
V: DeserializeOwned + Serialize + Default,
{
/// If input value implements `Default`, we can use `build` instead.
///
/// # Example
///
/// ```no_run
/// use serde::{Deserialize, Serialize};
/// use serfig::collectors::{from_env, from_file, from_self};
/// use serfig::parsers::Toml;
/// use serfig::Builder;
///
/// #[derive(Debug, Serialize, Deserialize, PartialEq, Default)]
/// #[serde(default)]
/// struct TestConfig {
/// a: String,
/// b: String,
/// c: i64,
/// }
///
/// fn main() -> anyhow::Result<()> {
/// let builder = Builder::default()
/// .collect(from_env())
/// .collect(from_file(Toml, "config.toml"));
///
/// let t = builder.build()?;
/// Ok(())
/// }
/// ```
pub fn build(self) -> Result<V> {
self.build_with(V::default())
}
}
#[cfg(test)]
mod tests {
use serde::{Deserialize, Serialize};
use super::*;
use crate::collectors::*;
use crate::parsers::Toml;
#[derive(Debug, Serialize, Deserialize, PartialEq, Default)]
#[serde(default)]
struct TestConfig {
test_a: String,
test_b: String,
}
#[test]
fn test_build() -> Result<()> {
temp_env::with_vars(
vec![("test_a", Some("test_a")), ("test_b", Some("test_b"))],
|| {
let cfg = Builder::default().collect(from_env());
let t: TestConfig = cfg.build().expect("must success");
assert_eq!(
t,
TestConfig {
test_a: "test_a".to_string(),
test_b: "test_b".to_string(),
}
)
},
);
Ok(())
}
#[test]
fn test_layered_build() -> Result<()> {
let _ = env_logger::try_init();
temp_env::with_vars(vec![("test_a", Some("test_a"))], || {
let cfg = Builder::default()
.collect(from_env())
.collect(from_str(Toml, r#"test_b = "test_b""#));
let t: TestConfig = cfg.build().expect("must success");
assert_eq!(
t,
TestConfig {
test_a: "test_a".to_string(),
test_b: "test_b".to_string(),
}
)
});
Ok(())
}
#[test]
fn test_layered_overwrite() -> Result<()> {
let _ = env_logger::try_init();
temp_env::with_vars(
vec![("test_a", Some("test_a")), ("test_b", Some("test_b"))],
|| {
let cfg = Builder::default()
.collect(from_env())
.collect(from_str(Toml, r#"test_b = "test_b_overwrite""#));
let t: TestConfig = cfg.build().expect("must success");
assert_eq!(
t,
TestConfig {
test_a: "test_a".to_string(),
test_b: "test_b_overwrite".to_string(),
}
)
},
);
temp_env::with_vars(
vec![("test_a", Some("test_a")), ("test_b", Some("test_b"))],
|| {
let cfg = Builder::default()
.collect(from_str(Toml, r#"test_b = "test_b_overwrite""#))
.collect(from_env());
let t: TestConfig = cfg.build().expect("must success");
assert_eq!(
t,
TestConfig {
test_a: "test_a".to_string(),
test_b: "test_b".to_string(),
}
)
},
);
Ok(())
}
#[derive(Debug, Serialize, Deserialize, PartialEq)]
#[serde(default)]
struct TestConfigDefault {
test_a: String,
test_b: String,
test_c: String,
test_d: String,
}
impl Default for TestConfigDefault {
fn default() -> Self {
Self {
test_a: String::new(),
test_b: "Hello, World!".to_string(),
test_c: "Default".to_string(),
test_d: "".to_string(),
}
}
}
#[test]
fn test_layered_build_default() -> Result<()> {
let _ = env_logger::try_init();
temp_env::with_vars(
vec![
("test_a", Some("test_a")),
("test_b", Some("test_b_from_env")),
],
|| {
let cfg = Builder::default()
.collect(from_env())
.collect(from_str(Toml, r#"test_b = "test_b""#))
.collect(from_str(Toml, r#"test_b = "Hello, World!""#))
.collect(from_self(TestConfigDefault {
test_d: "override".to_string(),
..Default::default()
}));
let t: TestConfigDefault = cfg.build().expect("must success");
assert_eq!(
t,
TestConfigDefault {
test_a: "test_a".to_string(),
test_b: "test_b".to_string(),
test_c: "Default".to_string(),
test_d: "override".to_string(),
}
)
},
);
Ok(())
}
#[derive(Debug, Serialize, Default, Deserialize, PartialEq)]
#[serde(default)]
struct TestConfigVec {
test_a: Vec<String>,
}
#[test]
fn test_layered_build_vec() -> Result<()> {
let _ = env_logger::try_init();
temp_env::with_vars(vec![("test_a", Some(""))], || {
let cfg = Builder::default()
.collect(from_env())
.collect(from_str(Toml, r#"test_a = ["test_b"]"#))
.collect(from_self(TestConfigVec::default()));
let t: TestConfigVec = cfg.build().expect("must success");
assert_eq!(
t,
TestConfigVec {
test_a: vec!["test_b".to_string()],
}
)
});
Ok(())
}
#[derive(Debug, Serialize, Deserialize, PartialEq)]
#[serde(default)]
struct TestConfigBool {
test_bool: bool,
}
impl Default for TestConfigBool {
fn default() -> Self {
Self { test_bool: true }
}
}
#[test]
fn test_config_bool_enabled() -> Result<()> {
let _ = env_logger::try_init();
temp_env::with_vars(vec![("test_bool", Some("false"))], || {
let cfg = Builder::default().collect(from_env());
let t: TestConfigBool = cfg.build().expect("must success");
assert_eq!(t, TestConfigBool { test_bool: false })
});
Ok(())
}
}