add support for Json in mssql

sqlx-core/src/mssql/types/json.rs

@@ -0,0 +1,53 @@
+use crate::decode::Decode;
+use crate::encode::{Encode, IsNull};
+use crate::error::BoxDynError;
+use crate::mssql::protocol::type_info::{DataType, TypeInfo};
+use crate::mssql::{Mssql, MssqlTypeInfo, MssqlValueRef};
+use crate::types::Json;
+use crate::types::Type;
+use serde::{Deserialize, Serialize};
+
+impl<T> Type<Mssql> for Json<T> {
+    fn type_info() -> MssqlTypeInfo {
+        MssqlTypeInfo(TypeInfo::new(DataType::BigVarBinary, 0))
+    }
+
+    fn compatible(ty: &MssqlTypeInfo) -> bool {
+        matches!(
+            ty.0.ty,
+            DataType::VarBinary
+                | DataType::Binary
+                | DataType::BigVarBinary
+                | DataType::BigBinary
+                | DataType::VarChar
+                | DataType::Char
+                | DataType::BigVarChar
+                | DataType::BigChar
+        )
+    }
+}
+
+impl<'q, T> Encode<'q, Mssql> for Json<T>
+where
+    T: Serialize,
+{
+    fn produces(&self) -> Option<MssqlTypeInfo> {
+        let size = 0xFF_FF;
+        return Some(MssqlTypeInfo(TypeInfo::new(DataType::BigVarBinary, size)));
+    }
+
+    fn encode_by_ref(&self, buf: &mut Vec<u8>) -> IsNull {
+        serde_json::to_writer(buf, self).unwrap();
+        IsNull::No
+    }
+}
+
+impl<'r, T: 'r> Decode<'r, Mssql> for Json<T>
+where
+    T: Deserialize<'r>,
+{
+    fn decode(value: MssqlValueRef<'r>) -> Result<Self, BoxDynError> {
+        let buf = value.as_bytes()?;
+        serde_json::from_slice(buf).map(Json).map_err(Into::into)
+    }
+}

sqlx-core/src/mssql/types/mod.rs

@@ -12,6 +12,9 @@ mod uint;
 #[cfg(feature = "chrono")]
 mod chrono;
 
+#[cfg(feature = "json")]
+mod json;
+
 impl<'q, T: 'q + Encode<'q, Mssql>> Encode<'q, Mssql> for Option<T> {
     fn encode(self, buf: &mut Vec<u8>) -> IsNull {
         if let Some(v) = self {

tests/mssql/types.rs

@@ -146,3 +146,14 @@ mod chrono {
         "CAST('00:00' AS TIME)" == NaiveTime::default(),
     ));
 }
+
+#[cfg(feature = "json")]
+mod json {
+    use super::*;
+    use serde_json::Value;
+    use sqlx_core::types::Json;
+
+    test_type!(json_value<Json<Value>>(Mssql,
+        r#"'123'"# == Json(Value::Number(123.into()))
+    ));
+}