feat!: Include key name in error (#73)

* feat!: Include key name in error

* typo

merde/examples/return-deserialize.rs

@@ -6,7 +6,7 @@ where
     T: OwnedValueDeserialize,
 {
     // here `s` is a `String`, but pretend we're making
-    // a network request intead — the point is is that we
+    // a network request instead — the point is is that we
     // need to borrow from a local from the function body.
     let value: Value = merde_json::from_str_via_value(&s).map_err(|e| e.to_static())?;
     Ok(T::owned_from_value(Some(value))?)

merde_core/src/deserialize.rs

@@ -318,7 +318,10 @@ where
             Some(Value::Map(obj)) => {
                 let mut map = std::collections::HashMap::new();
                 for (key, val) in obj.iter() {
-                    let parsed_key = K::from_str(key).map_err(|_| MerdeError::InvalidKey)?;
+                    let parsed_key = K::from_str(key).map_err(|_| MerdeError::InvalidKey {
+                        key: key.clone().into_static(),
+                        type_name: std::any::type_name::<K>(),
+                    })?;
                     let parsed_value = V::from_value_ref(Some(val))?;
                     map.insert(parsed_key, parsed_value);
                 }

merde_core/src/error.rs

@@ -71,7 +71,10 @@ pub enum MerdeError {
     MissingValue,
 
     /// While calling out to [`FromStr::from_str`](std::str::FromStr::from_str) to build a [`HashMap`](std::collections::HashMap), we got an error.
-    InvalidKey,
+    InvalidKey {
+        key: CowStr<'static>,
+        type_name: &'static str,
+    },
 
     /// While parsing a datetime, we got an error
     InvalidDateTimeValue,
@@ -111,8 +114,12 @@ impl std::fmt::Display for MerdeError {
             MerdeError::MissingValue => {
                 write!(f, "Missing value")
             }
-            MerdeError::InvalidKey => {
-                write!(f, "Invalid key")
+            MerdeError::InvalidKey { key, type_name } => {
+                write!(
+                    f,
+                    "Invalid key: couldn't convert {:?} to type {}",
+                    key, type_name
+                )
             }
             MerdeError::InvalidDateTimeValue => {
                 write!(f, "Invalid date/time value")