fix #925 support bigdecimal

Cargo.toml

@@ -68,6 +68,7 @@ opentelemetry = { version = "0.17.0", optional = true, default-features = false,
   "trace",
 ] }
 rust_decimal = { version = "1.14.3", optional = true }
+bigdecimal = { version = "0.3.0", optional = true }
 secrecy = { version = "0.8.0", optional = true }
 smol_str = { version = "0.1.21", optional = true }
 time = { version = "0.3.5", optional = true, features = [

src/types/external/big_decimal.rs

@@ -0,0 +1,31 @@
+use std::str::FromStr;
+
+use bigdecimal::BigDecimal;
+
+use crate::{InputValueError, InputValueResult, Scalar, ScalarType, Value};
+
+#[Scalar(internal, name = "BigDecimal")]
+impl ScalarType for BigDecimal {
+    fn parse(value: Value) -> InputValueResult<Self> {
+        match &value {
+            Value::Number(n) => {
+                if let Some(f) = n.as_f64() {
+                    return BigDecimal::try_from(f).map_err(InputValueError::custom);
+                }
+
+                if let Some(f) = n.as_i64() {
+                    return Ok(BigDecimal::from(f)); 
+                }
+
+                // unwrap safe here, because we have check the other possibility
+                Ok(BigDecimal::from(n.as_u64().unwrap()))
+            },
+            Value::String(s) => Ok(BigDecimal::from_str(s)?),
+            _ => Err(InputValueError::expected_type(value)),
+        }
+    }
+
+    fn to_value(&self) -> Value {
+        Value::String(self.to_string())
+    }
+}

src/types/external/decimal.rs

@@ -9,6 +9,18 @@ impl ScalarType for Decimal {
     fn parse(value: Value) -> InputValueResult<Self> {
         match &value {
             Value::String(s) => Ok(Decimal::from_str(s)?),
+            Value::Number(n) => {
+                if let Some(f) = n.as_f64() {
+                    return Decimal::try_from(f).map_err(InputValueError::custom);
+                }
+
+                if let Some(f) = n.as_i64() {
+                    return Ok(Decimal::from(f)); 
+                }
+
+                // unwrap safe here, because we have check the other possibility
+                Ok(Decimal::from(n.as_u64().unwrap()))
+            },
             _ => Err(InputValueError::expected_type(value)),
         }
     }

src/types/external/mod.rs

@@ -23,6 +23,8 @@ mod chrono_tz;
 mod datetime;
 #[cfg(feature = "decimal")]
 mod decimal;
+#[cfg(feature = "bigdecimal")]
+mod big_decimal;
 #[cfg(feature = "chrono-duration")]
 mod duration;
 #[cfg(feature = "chrono")]