Merge pull request #40 from LukasKalbertodt/validation

Add Validation via `#[config(validate)]`

Cargo.toml

@@ -19,11 +19,19 @@ exclude = [".github"]
 name = "simple"
 required-features = ["toml"]
 
+[[example]]
+name = "validate"
+required-features = ["toml"]
+
 [[test]]
 name = "indirect-serde"
 path = "tests/indirect-serde/run.rs"
 harness = false
 
+[[test]]
+name = "validation"
+required-features = ["toml"]
+
 
 [features]
 default = ["toml", "yaml", "json5"]

examples/files/validate.toml

@@ -0,0 +1,6 @@
+name = "peter"
+port = 1234
+
+[watch]
+busy_poll = true
+poll_period = 300

examples/validate.rs

@@ -0,0 +1,82 @@
+//! This example demonstrates the usage of validators for single fields or whole
+//! structs. Try editing `files/validate.toml` to see different errors. Also
+//! see the docs.
+
+use std::time::Duration;
+
+use confique::Config;
+
+
+#[derive(Debug, Config)]
+#[allow(dead_code)]
+struct Conf {
+    // Here, the validator is a function returning `Result<(), impl Display>`.
+    #[config(validate = validate_name)]
+    name: String,
+
+    // For simple cases, validation can be written in this `assert!`-like style.
+    #[config(env = "PORT", validate(*port >= 1024, "port must not require super-user"))]
+    port: Option<u16>,
+
+    #[config(nested)]
+    watch: WatchConfig,
+}
+
+// You can also add validators for whole structs, which are called later in the
+// pipeline, when all layers are already merged. These validators allow you to
+// check fields in relationship to one another, e.g. maybe one field only makes
+// sense to be set whenever another one has a specific value.
+#[derive(Debug, Config)]
+#[config(validate = Self::validate)]
+struct WatchConfig {
+    #[config(default = false)]
+    busy_poll: bool,
+
+    #[config(
+        deserialize_with = deserialize_duration_ms,
+        validate(*poll_period > Duration::from_millis(10), "cannot poll faster than 10ms"),
+    )]
+    poll_period: Option<Duration>,
+}
+
+fn validate_name(name: &String) -> Result<(), &'static str> {
+    if name.is_empty() {
+        return Err("name must be non-empty");
+    }
+    if !name.is_ascii() {
+        return Err("name must be ASCII");
+    }
+    Ok(())
+}
+
+impl WatchConfig {
+    fn validate(&self) -> Result<(), &'static str> {
+        if !self.busy_poll && self.poll_period.is_some() {
+            return Err("'poll_period' set, but busy polling is not enabled");
+        }
+
+        Ok(())
+    }
+}
+
+
+pub(crate) fn deserialize_duration_ms<'de, D>(deserializer: D) -> Result<Duration, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    let ms = <u64 as serde::Deserialize>::deserialize(deserializer)?;
+    Ok(Duration::from_millis(ms))
+}
+
+
+fn main() {
+    let r = Conf::builder()
+        .env()
+        .file("examples/files/validate.toml")
+        .load();
+
+    match r {
+        Ok(conf) => println!("{:#?}", conf),
+        Err(e) => println!("{e:#}"),
+    }
+}