feat: add (optional) serde_json conversion support (#45)

Signed-off-by: YUE Daian <[email protected]>

Cargo.toml

@@ -16,12 +16,15 @@ maintenance = { status = "actively-developed" }
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-anyhow = "1.0"
 async-trait = "0.1.74"
 lazy_static = "1.4.0"
+serde_json = { version = "1.0.108", optional = true }
 time = "0.3.30"
 tokio = { version = "1.35.0", features = [ "full" ] }
 typed-builder = "0.18.0"
 
 [dev-dependencies]
 spec = { path = "spec" }
+
+[features]
+serde_json = ["dep:serde_json"]

src/lib.rs

@@ -28,3 +28,7 @@ pub use evaluation::*;
 
 /// Feature provider related.
 pub mod provider;
+
+/// Optional support for [`serde_json::Value`].
+#[cfg(feature = "serde_json")]
+pub mod serde_json;

src/provider/no_op_provider.rs

@@ -115,7 +115,7 @@ impl FeatureProvider for NoOpProvider {
         _flag_key: &str,
         evaluation_context: &EvaluationContext,
     ) -> Result<ResolutionDetails<bool>, EvaluationError> {
-        let (reason, variant) = Self::create_reason_variant(self.bool_value == Default::default());
+        let (reason, variant) = Self::create_reason_variant(self.bool_value == bool::default());
 
         let mut flag_metadata = FlagMetadata::default().with_value("Type", "Bool");
         Self::populate_evaluation_context_values(&mut flag_metadata, evaluation_context);
@@ -133,7 +133,7 @@ impl FeatureProvider for NoOpProvider {
         _flag_key: &str,
         evaluation_context: &EvaluationContext,
     ) -> Result<ResolutionDetails<i64>, EvaluationError> {
-        let (reason, variant) = Self::create_reason_variant(self.int_value == Default::default());
+        let (reason, variant) = Self::create_reason_variant(self.int_value == i64::default());
 
         let mut flag_metadata = FlagMetadata::default().with_value("Type", "Int");
         Self::populate_evaluation_context_values(&mut flag_metadata, evaluation_context);

src/serde_json.rs

@@ -0,0 +1,111 @@
+use crate::{EvaluationError, EvaluationResult, StructValue, Value};
+
+impl TryFrom<serde_json::Value> for Value {
+    type Error = EvaluationError;
+
+    fn try_from(value: serde_json::Value) -> Result<Self, Self::Error> {
+        json_value_to_value(&value)
+    }
+}
+
+fn json_value_to_value(value: &serde_json::Value) -> EvaluationResult<Value> {
+    match value {
+        serde_json::Value::Bool(value) => Ok(Value::Bool(*value)),
+        serde_json::Value::Number(value) if value.is_i64() => {
+            Ok(Value::Int(value.as_i64().unwrap()))
+        }
+        serde_json::Value::Number(value) if value.is_f64() => {
+            Ok(Value::Float(value.as_f64().unwrap()))
+        }
+        serde_json::Value::String(value) => Ok(Value::String(value.to_string())),
+        serde_json::Value::Array(array) => Ok(Value::Array(
+            array
+                .iter()
+                .map(|x| json_value_to_value(x))
+                .collect::<Result<Vec<_>, _>>()?,
+        )),
+        serde_json::Value::Object(object) => {
+            let mut result = StructValue::default();
+
+            for (key, value) in object {
+                result.add_field(key, json_value_to_value(value)?);
+            }
+
+            Ok(Value::Struct(result))
+        }
+        _ => Err(EvaluationError::builder()
+            .code(crate::EvaluationErrorCode::TypeMismatch)
+            .message("Failed to convert from JSON")
+            .build()),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{StructValue, Value};
+
+    #[test]
+    fn convert_data() {
+        let json = serde_json::json!({
+            "id": 100,
+            "name": "Bob",
+            "age": 23.5,
+            "active": true,
+            "phones": [
+                "12345",
+                "67890",
+                [123, 456]
+            ],
+            "children": [{
+                "name": "Carl",
+                "gender": "male"
+            }, {
+                "name": "Dina",
+                "gender": "female",
+            }]
+        });
+
+        let expected_value = Value::Struct(
+            StructValue::default()
+                .with_field("id", 100)
+                .with_field("name", "Bob")
+                .with_field("age", 23.5)
+                .with_field("active", true)
+                .with_field(
+                    "phones",
+                    Value::Array(vec![
+                        "12345".into(),
+                        "67890".into(),
+                        Value::Array(vec![123.into(), 456.into()]),
+                    ]),
+                )
+                .with_field(
+                    "children",
+                    Value::Array(vec![
+                        Value::Struct(
+                            StructValue::default()
+                                .with_field("name", "Carl")
+                                .with_field("gender", "male"),
+                        ),
+                        Value::Struct(
+                            StructValue::default()
+                                .with_field("name", "Dina")
+                                .with_field("gender", "female"),
+                        ),
+                    ]),
+                ),
+        );
+
+        let actual_value: Value = json.try_into().unwrap();
+
+        assert_eq!(expected_value, actual_value);
+    }
+
+    #[test]
+    fn convert_invalid_data() {
+        let json = serde_json::Value::Null;
+        let result = Value::try_from(json);
+
+        assert!(result.is_err());
+    }
+}