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Environment Variable List of Structs #597

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Environment Variable List of Structs #597

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2197eae
env list of structs
ewoolsey Oct 31, 2024
65231a0
tests and docs
ewoolsey Oct 31, 2024
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29 changes: 28 additions & 1 deletion examples/env-list/main.rs
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Original file line number Diff line number Diff line change
@@ -1,25 +1,52 @@
use config::Config;

#[derive(Debug, Default, serde_derive::Deserialize, PartialEq, Eq)]
struct ListOfStructs {
a: String,
b: String,
}

#[derive(Debug, Default, serde_derive::Deserialize, PartialEq, Eq)]
struct AppConfig {
list: Vec<String>,
structs: Vec<Option<ListOfStructs>>,
}

fn main() {
std::env::set_var("APP_LIST", "Hello World");
std::env::set_var("APP_STRUCTS_0_A", "Hello");
std::env::set_var("APP_STRUCTS_0_B", "World");
std::env::set_var("APP_STRUCTS_2_A", "foo");
std::env::set_var("APP_STRUCTS_2_B", "bar");

let config = Config::builder()
.add_source(
config::Environment::with_prefix("APP")
.try_parsing(true)
.separator("_")
.list_separator(" "),
.list_separator(" ")
.with_list_parse_key("list"),
)
.build()
.unwrap();

let app: AppConfig = config.try_deserialize().unwrap();

assert_eq!(app.list, vec![String::from("Hello"), String::from("World")]);
assert_eq!(
app.structs,
vec![
Some(ListOfStructs {
a: String::from("Hello"),
b: String::from("World")
}),
None,
Some(ListOfStructs {
a: String::from("foo"),
b: String::from("bar")
}),
]
);

std::env::remove_var("APP_LIST");
}
120 changes: 105 additions & 15 deletions src/env.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ use crate::error::Result;
use crate::map::Map;
use crate::source::Source;
use crate::value::{Value, ValueKind};
use crate::ConfigError;

#[cfg(feature = "convert-case")]
use convert_case::{Case, Casing};
Expand All @@ -12,6 +13,63 @@ use convert_case::{Case, Casing};
/// config Value type. We have to be aware how the config tree is created from the environment
/// dictionary, therefore we are mindful about prefixes for the environment keys, level separators,
/// encoding form (kebab, snake case) etc.
///
/// Environment variables are specified using the path to the key they correspond to. When
/// specifying a value within a list, the index should be specified in the key immediately after
/// the list type.
///
/// ## Example
///
/// ```rust
/// # use config::{Environment, Config};
/// # use serde::Deserialize;
/// # use std::collections::HashMap;
/// # use std::convert::TryInto;
/// #
/// # #[test]
/// # fn test_env_list_of_structs() {
/// #[derive(Deserialize, Debug, PartialEq)]
/// struct Struct {
/// a: Vec<Option<u32>>,
/// b: u32,
/// }
///
/// #[derive(Deserialize, Debug)]
/// struct ListOfStructs {
/// list: Vec<Struct>,
/// }
///
/// let values = vec![
/// ("LIST_0_A_0".to_owned(), "1".to_owned()),
/// ("LIST_0_A_2".to_owned(), "2".to_owned()),
/// ("LIST_0_B".to_owned(), "3".to_owned()),
/// ("LIST_1_A_1".to_owned(), "4".to_owned()),
/// ("LIST_1_B".to_owned(), "5".to_owned()),
/// ];
///
/// let environment = Environment::default()
/// .separator("_")
/// .try_parsing(true)
/// .source(Some(values.into_iter().collect()));
///
/// let config = Config::builder().add_source(environment).build().unwrap();
///
/// let config: ListOfStructs = config.try_deserialize().unwrap();
/// assert_eq!(
/// config.list,
/// vec![
/// Struct {
/// a: vec![Some(1), None, Some(2)],
/// b: 3
/// },
/// Struct {
/// a: vec![None, Some(4)],
/// b: 5
/// },
/// ]
/// );
/// # }
/// ```
#[must_use]
#[derive(Clone, Debug, Default)]
pub struct Environment {
Expand Down Expand Up @@ -230,8 +288,8 @@ impl Source for Environment {
}

fn collect(&self) -> Result<Map<String, Value>> {
let mut m = Map::new();
let uri: String = "the environment".into();
let mut m = Value::new(Some(&uri), ValueKind::Table(Map::new()));

let separator = self.separator.as_deref().unwrap_or("");
#[cfg(feature = "convert-case")]
Expand All @@ -248,24 +306,25 @@ impl Source for Environment {
.as_ref()
.map(|prefix| format!("{prefix}{prefix_separator}").to_lowercase());

let collector = |(key, value): (String, String)| {
let collector = |(key, value): (String, String)| -> Result<()> {
// Treat empty environment variables as unset
if self.ignore_empty && value.is_empty() {
return;
return Ok(());
}

let mut key = key.to_lowercase();

// Check for prefix
let mut kept_prefix = String::new();
if let Some(ref prefix_pattern) = prefix_pattern {
if key.starts_with(prefix_pattern) {
if !self.keep_prefix {
// Remove this prefix from the key
key = key[prefix_pattern.len()..].to_string();
key = key[prefix_pattern.len()..].to_string();
if self.keep_prefix {
kept_prefix = prefix_pattern.clone();
}
} else {
// Skip this key
return;
return Ok(());
}
}

Expand All @@ -277,9 +336,10 @@ impl Source for Environment {
#[cfg(feature = "convert-case")]
if let Some(convert_case) = convert_case {
key = key.to_case(*convert_case);
kept_prefix = kept_prefix.to_case(*convert_case);
}

let value = if self.try_parsing {
let value_kind = if self.try_parsing {
// convert to lowercase because bool parsing expects all lowercase
if let Ok(parsed) = value.to_lowercase().parse::<bool>() {
ValueKind::Boolean(parsed)
Expand All @@ -288,11 +348,10 @@ impl Source for Environment {
} else if let Ok(parsed) = value.parse::<f64>() {
ValueKind::Float(parsed)
} else if let Some(separator) = &self.list_separator {
if let Some(keys) = &self.list_parse_keys {
if let Some(parse_keys) = &self.list_parse_keys {
#[cfg(feature = "convert-case")]
let key = key.to_lowercase();

if keys.contains(&key) {
if parse_keys.contains(&key) {
let v: Vec<Value> = value
.split(separator)
.map(|s| Value::new(Some(&uri), ValueKind::String(s.to_owned())))
Expand All @@ -315,14 +374,45 @@ impl Source for Environment {
ValueKind::String(value)
};

m.insert(key, Value::new(Some(&uri), value));
let value = Value::new(Some(&uri), value_kind);
let mut key_parts = key.split('.');
let key = key_parts
.next()
.ok_or(ConfigError::Message("No key after prefix".to_owned()))?;

let value = key_parts
.rev()
.fold(value, |value, key| match key.parse::<usize>() {
Ok(index) => {
let nil = Value::new(Some(&uri), ValueKind::Nil);
let mut array = vec![nil; index + 1];
array[index] = value;
Value::new(Some(&uri), ValueKind::Array(array))
}
Err(_) => {
let mut map = Map::new();
map.insert(key.to_owned(), value);
Value::new(Some(&uri), ValueKind::Table(map))
}
});

let mut map = Map::new();
kept_prefix.push_str(key);
map.insert(kept_prefix, value);
let table = Value::new(Some(&uri), ValueKind::Table(map));

m.merge(table);
Ok(())
};

match &self.source {
Some(source) => source.clone().into_iter().for_each(collector),
None => env::vars().for_each(collector),
Some(source) => source.clone().into_iter().try_for_each(collector)?,
None => env::vars().try_for_each(collector)?,
}

Ok(m)
match m.kind {
ValueKind::Table(m) => Ok(m),
_ => unreachable!(),
}
}
}
34 changes: 34 additions & 0 deletions src/value.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -705,6 +705,40 @@ impl Value {
)),
}
}

/// Merge the value with another value recursively.
///
/// In the case of a conflict, the other value (on the right) will take precedence.
pub(crate) fn merge(&mut self, other: Self) {
match (&mut self.kind, other.kind) {
(ValueKind::Table(ref mut table), ValueKind::Table(other_table)) => {
for (k, v) in other_table {
match table.entry(k) {
std::collections::hash_map::Entry::Occupied(mut entry) => {
entry.get_mut().merge(v);
}
std::collections::hash_map::Entry::Vacant(entry) => {
entry.insert(v);
}
}
}
}
(ValueKind::Array(ref mut array), ValueKind::Array(other)) => {
for (i, other) in other.into_iter().enumerate() {
if let Some(s) = array.get_mut(i) {
if other.kind != ValueKind::Nil {
s.merge(other);
}
} else {
array.push(other);
}
}
}
(s, other) => {
*s = other;
}
}
}
}

impl<'de> Deserialize<'de> for Value {
Expand Down
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