diff --git a/async-graphql-derive/src/enum.rs b/async-graphql-derive/src/enum.rs
index 600455d9..499a38f8 100644
--- a/async-graphql-derive/src/enum.rs
+++ b/async-graphql-derive/src/enum.rs
@@ -101,10 +101,6 @@ pub fn generate(enum_args: &args::Enum, input: &DeriveInput) -> Result<TokenStre
             fn parse(value: &#crate_name::Value) -> Option<Self> {
                 #crate_name::GQLEnum::parse_enum(value)
             }
-
-            fn parse_from_json(value: &#crate_name::serde_json::Value) -> Option<Self> {
-                #crate_name::GQLEnum::parse_json_enum(value)
-            }
         }
 
         #[#crate_name::async_trait::async_trait]
diff --git a/async-graphql-derive/src/input_object.rs b/async-graphql-derive/src/input_object.rs
index c64f45d1..515f3265 100644
--- a/async-graphql-derive/src/input_object.rs
+++ b/async-graphql-derive/src/input_object.rs
@@ -41,7 +41,6 @@ pub fn generate(object_args: &args::InputObject, input: &DeriveInput) -> Result<
         .unwrap_or_else(|| quote! {None});
 
     let mut get_fields = Vec::new();
-    let mut get_json_fields = Vec::new();
     let mut fields = Vec::new();
     let mut schema_fields = Vec::new();
 
@@ -83,25 +82,6 @@ pub fn generate(object_args: &args::InputObject, input: &DeriveInput) -> Result<
             });
         }
 
-        if let Some(default) = &field_args.default {
-            let default_repr = build_value_repr(&crate_name, default);
-            get_json_fields.push(quote! {
-                let #ident:#ty = match obj.get(#name) {
-                    None => {
-                        let default_value = #default_repr;
-                        #crate_name::GQLInputValue::parse(&default_value)?
-                    }
-                    Some(value) => {
-                        #crate_name::GQLInputValue::parse_from_json(&value)?
-                    }
-                };
-            });
-        } else {
-            get_json_fields.push(quote! {
-                let #ident:#ty = #crate_name::GQLInputValue::parse_from_json(&obj.get(#name).unwrap_or(&#crate_name::serde_json::Value::Null))?;
-            });
-        }
-
         fields.push(ident);
         schema_fields.push(quote! {
             #crate_name::registry::InputValue {
@@ -141,16 +121,6 @@ pub fn generate(object_args: &args::InputObject, input: &DeriveInput) -> Result<
                     None
                 }
             }
-
-            fn parse_from_json(value: &#crate_name::serde_json::Value) -> Option<Self> {
-                use #crate_name::GQLType;
-                if let #crate_name::serde_json::Value::Object(obj) = value {
-                    #(#get_json_fields)*
-                    Some(Self { #(#fields),* })
-                } else {
-                    None
-                }
-            }
         }
 
         impl #crate_name::GQLInputObject for #ident {}
diff --git a/examples/helloworld.rs b/examples/helloworld.rs
index c1c7685f..2b53a7bb 100644
--- a/examples/helloworld.rs
+++ b/examples/helloworld.rs
@@ -43,16 +43,16 @@ impl MyObjFields for MyObj {
 #[async_std::main]
 async fn main() {
     let schema = async_graphql::Schema::<MyObj, async_graphql::GQLEmptyMutation>::new();
-    for _ in 0..1000 {
-        let res = schema
-            .query(
-                MyObj { value: 100 },
-                async_graphql::GQLEmptyMutation,
-                "{ a b c __schema { types { kind name description fields(includeDeprecated: false) { name args { name defaultValue } } } } }",
-            )
-            .execute()
-            .await
-            .unwrap();
-    }
-    // serde_json::to_writer_pretty(std::io::stdout(), &res).unwrap();
+    let vars = async_graphql::Variables::parse_from_json(b"{\"myvar\": 999}").unwrap();
+    let res = schema
+        .query(
+            MyObj { value: 100 },
+            async_graphql::GQLEmptyMutation,
+            "query($myvar:Int) { a b(v:$myvar) }",
+        )
+        .variables(&vars)
+        .execute()
+        .await
+        .unwrap();
+    serde_json::to_writer_pretty(std::io::stdout(), &res).unwrap();
 }
diff --git a/src/base.rs b/src/base.rs
index 302ba204..0e71a88b 100644
--- a/src/base.rs
+++ b/src/base.rs
@@ -16,7 +16,6 @@ pub trait GQLType {
 #[doc(hidden)]
 pub trait GQLInputValue: GQLType + Sized {
     fn parse(value: &Value) -> Option<Self>;
-    fn parse_from_json(value: &serde_json::Value) -> Option<Self>;
 }
 
 #[doc(hidden)]
@@ -37,7 +36,6 @@ pub trait Scalar: Sized + Send {
         None
     }
     fn parse(value: &Value) -> Option<Self>;
-    fn parse_from_json(value: &serde_json::Value) -> Option<Self>;
     fn to_json(&self) -> Result<serde_json::Value>;
 }
 
@@ -58,10 +56,6 @@ impl<T: Scalar> GQLInputValue for T {
     fn parse(value: &Value) -> Option<Self> {
         T::parse(value)
     }
-
-    fn parse_from_json(value: &serde_json::Value) -> Option<Self> {
-        T::parse_from_json(value)
-    }
 }
 
 #[async_trait::async_trait]
diff --git a/src/context.rs b/src/context.rs
index 3daeae9d..71fb5b12 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -1,23 +1,55 @@
 use crate::registry::Registry;
 use crate::{ErrorWithPosition, GQLInputValue, QueryError, Result};
 use fnv::FnvHasher;
-use graphql_parser::query::{Field, SelectionSet, Value};
+use graphql_parser::query::{Field, SelectionSet, Value, VariableDefinition};
 use std::any::{Any, TypeId};
-use std::collections::HashMap;
+use std::collections::{BTreeMap, HashMap};
 use std::hash::BuildHasherDefault;
 use std::ops::{Deref, DerefMut};
 
 #[derive(Default)]
-pub struct Variables(HashMap<String, serde_json::Value>);
+pub struct Variables(BTreeMap<String, Value>);
 
 impl Deref for Variables {
-    type Target = HashMap<String, serde_json::Value>;
+    type Target = BTreeMap<String, Value>;
 
     fn deref(&self) -> &Self::Target {
         &self.0
     }
 }
 
+impl Variables {
+    pub fn parse_from_json(data: &[u8]) -> Result<Self> {
+        let value = serde_json::from_slice(data)?;
+        let gql_value = json_value_to_gql_value(value);
+        if let Value::Object(obj) = gql_value {
+            Ok(Variables(obj))
+        } else {
+            Ok(Default::default())
+        }
+    }
+}
+
+fn json_value_to_gql_value(value: serde_json::Value) -> Value {
+    match value {
+        serde_json::Value::Null => Value::Null,
+        serde_json::Value::Bool(n) => Value::Boolean(n),
+        serde_json::Value::Number(n) if n.is_f64() => Value::Float(n.as_f64().unwrap()),
+        serde_json::Value::Number(n) => Value::Int((n.as_i64().unwrap() as i32).into()),
+        serde_json::Value::String(s) => Value::String(s),
+        serde_json::Value::Array(ls) => Value::List(
+            ls.into_iter()
+                .map(|value| json_value_to_gql_value(value))
+                .collect(),
+        ),
+        serde_json::Value::Object(obj) => Value::Object(
+            obj.into_iter()
+                .map(|(name, value)| (name, json_value_to_gql_value(value)))
+                .collect(),
+        ),
+    }
+}
+
 impl DerefMut for Variables {
     fn deref_mut(&mut self) -> &mut Self::Target {
         &mut self.0
@@ -44,6 +76,7 @@ pub struct ContextBase<'a, T> {
     pub(crate) item: T,
     pub(crate) data: Option<&'a Data>,
     pub(crate) variables: Option<&'a Variables>,
+    pub(crate) variable_definitions: Option<&'a [VariableDefinition]>,
     pub(crate) registry: &'a Registry,
 }
 
@@ -62,6 +95,7 @@ impl<'a, T> ContextBase<'a, T> {
             item,
             data: self.data,
             variables: self.variables,
+            variable_definitions: self.variable_definitions,
             registry: self.registry.clone(),
         }
     }
@@ -76,35 +110,40 @@ impl<'a, T> ContextBase<'a, T> {
 }
 
 impl<'a> ContextBase<'a, &'a Field> {
+    fn resolve_input_value(&self, value: Value) -> Result<Value> {
+        if let Value::Variable(var_name) = value {
+            let def = self
+                .variable_definitions
+                .and_then(|defs| defs.iter().find(|def| def.name == var_name.as_str()));
+            if let Some(def) = def {
+                if let Some(var_value) = self.variables.map(|vars| vars.get(&def.name)).flatten() {
+                    return Ok(var_value.clone());
+                }
+            }
+            return Err(QueryError::VarNotDefined {
+                var_name: var_name.clone(),
+            }
+            .into());
+        } else {
+            Ok(value)
+        }
+    }
+
     #[doc(hidden)]
     pub fn param_value<T: GQLInputValue, F: FnOnce() -> Value>(
         &self,
         name: &str,
         default: Option<F>,
     ) -> Result<T> {
-        let value = self
+        match self
             .arguments
             .iter()
             .find(|(n, _)| n == name)
             .map(|(_, v)| v)
-            .cloned();
-
-        if let Some(Value::Variable(var_name)) = &value {
-            if let Some(vars) = &self.variables {
-                if let Some(var_value) = vars.get(&*var_name).cloned() {
-                    let res = GQLInputValue::parse_from_json(&var_value).ok_or_else(|| {
-                        QueryError::ExpectedJsonType {
-                            expect: T::qualified_type_name(),
-                            actual: var_value,
-                        }
-                        .with_position(self.item.position)
-                    })?;
-                    return Ok(res);
-                }
-            }
-
-            if let Some(default) = default {
-                let value = default();
+            .cloned()
+        {
+            Some(value) => {
+                let value = self.resolve_input_value(value)?;
                 let res = GQLInputValue::parse(&value).ok_or_else(|| {
                     QueryError::ExpectedType {
                         expect: T::qualified_type_name(),
@@ -112,28 +151,30 @@ impl<'a> ContextBase<'a, &'a Field> {
                     }
                     .with_position(self.item.position)
                 })?;
-                return Ok(res);
+                Ok(res)
             }
-
-            return Err(QueryError::VarNotDefined {
-                var_name: var_name.clone(),
+            None if default.is_some() => {
+                let default = default.unwrap();
+                let value = default();
+                let res = GQLInputValue::parse(&value).ok_or_else(|| {
+                    QueryError::ExpectedType {
+                        expect: T::qualified_type_name(),
+                        actual: value.clone(),
+                    }
+                    .with_position(self.item.position)
+                })?;
+                Ok(res)
             }
-            .into());
-        };
-
-        let value = if let (Some(default), None) = (default, &value) {
-            default()
-        } else {
-            value.unwrap_or(Value::Null)
-        };
-
-        let res = GQLInputValue::parse(&value).ok_or_else(|| {
-            QueryError::ExpectedType {
-                expect: T::qualified_type_name(),
-                actual: value,
+            None => {
+                let res = GQLInputValue::parse(&Value::Null).ok_or_else(|| {
+                    QueryError::ExpectedType {
+                        expect: T::qualified_type_name(),
+                        actual: Value::Null,
+                    }
+                    .with_position(self.item.position)
+                })?;
+                Ok(res)
             }
-            .with_position(self.item.position)
-        })?;
-        Ok(res)
+        }
     }
 }
diff --git a/src/scalars/bool.rs b/src/scalars/bool.rs
index cbf1e9b7..0a1a7551 100644
--- a/src/scalars/bool.rs
+++ b/src/scalars/bool.rs
@@ -16,13 +16,6 @@ impl Scalar for bool {
         }
     }
 
-    fn parse_from_json(value: &serde_json::Value) -> Option<Self> {
-        match value {
-            serde_json::Value::Bool(n) => Some(*n),
-            _ => None,
-        }
-    }
-
     fn to_json(&self) -> Result<serde_json::Value> {
         Ok((*self).into())
     }
diff --git a/src/scalars/datetime.rs b/src/scalars/datetime.rs
index b7784f73..8f8f4e13 100644
--- a/src/scalars/datetime.rs
+++ b/src/scalars/datetime.rs
@@ -13,13 +13,6 @@ impl Scalar for DateTime<Utc> {
         }
     }
 
-    fn parse_from_json(value: &serde_json::Value) -> Option<Self> {
-        match value {
-            serde_json::Value::String(s) => Some(Utc.datetime_from_str(&s, "%+").ok()?),
-            _ => None,
-        }
-    }
-
     fn to_json(&self) -> Result<serde_json::Value> {
         Ok(self.to_rfc3339().into())
     }
diff --git a/src/scalars/floats.rs b/src/scalars/floats.rs
index 5752f3f8..60fad35c 100644
--- a/src/scalars/floats.rs
+++ b/src/scalars/floats.rs
@@ -20,13 +20,6 @@ macro_rules! impl_float_scalars {
                 }
             }
 
-            fn parse_from_json(value: &serde_json::Value) -> Option<Self> {
-                match value {
-                    serde_json::Value::Number(n) => Some(n.as_f64().unwrap() as Self),
-                    _ => None
-                }
-            }
-
             fn to_json(&self) -> Result<serde_json::Value> {
                 Ok((*self).into())
             }
diff --git a/src/scalars/id.rs b/src/scalars/id.rs
index 0b8b3caf..8d9ca0e5 100644
--- a/src/scalars/id.rs
+++ b/src/scalars/id.rs
@@ -31,14 +31,6 @@ impl Scalar for ID {
         }
     }
 
-    fn parse_from_json(value: &serde_json::Value) -> Option<Self> {
-        match value {
-            serde_json::Value::Number(n) if n.is_i64() => Some(ID(n.as_i64().unwrap().to_string())),
-            serde_json::Value::String(s) => Some(ID(s.clone())),
-            _ => None,
-        }
-    }
-
     fn to_json(&self) -> Result<serde_json::Value> {
         Ok(self.0.clone().into())
     }
diff --git a/src/scalars/integers.rs b/src/scalars/integers.rs
index def161e7..e1fa63b6 100644
--- a/src/scalars/integers.rs
+++ b/src/scalars/integers.rs
@@ -19,14 +19,6 @@ macro_rules! impl_integer_scalars {
                 }
             }
 
-            fn parse_from_json(value: &serde_json::Value) -> Option<Self> {
-                match value {
-                    serde_json::Value::Number(n) if n.is_i64() => Some(n.as_i64().unwrap() as Self),
-                    serde_json::Value::Number(n) => Some(n.as_f64().unwrap() as Self),
-                    _ => None,
-                }
-            }
-
             fn to_json(&self) -> Result<serde_json::Value> {
                 Ok((*self).into())
             }
diff --git a/src/scalars/string.rs b/src/scalars/string.rs
index 5e2f51d1..cc92851d 100644
--- a/src/scalars/string.rs
+++ b/src/scalars/string.rs
@@ -20,13 +20,6 @@ impl Scalar for String {
         }
     }
 
-    fn parse_from_json(value: &serde_json::Value) -> Option<Self> {
-        match value {
-            serde_json::Value::String(s) => Some(s.clone()),
-            _ => None,
-        }
-    }
-
     fn to_json(&self) -> Result<serde_json::Value> {
         Ok(self.clone().into())
     }
diff --git a/src/scalars/uuid.rs b/src/scalars/uuid.rs
index 70164d95..acd39703 100644
--- a/src/scalars/uuid.rs
+++ b/src/scalars/uuid.rs
@@ -13,13 +13,6 @@ impl Scalar for Uuid {
         }
     }
 
-    fn parse_from_json(value: &serde_json::Value) -> Option<Self> {
-        match value {
-            serde_json::Value::String(s) => Some(Uuid::parse_str(&s).ok()?),
-            _ => None,
-        }
-    }
-
     fn to_json(&self) -> Result<serde_json::Value> {
         Ok(self.to_string().into())
     }
diff --git a/src/schema.rs b/src/schema.rs
index 79f319e6..ee334e92 100644
--- a/src/schema.rs
+++ b/src/schema.rs
@@ -96,6 +96,7 @@ impl<'a, Query, Mutation> QueryBuilder<'a, Query, Mutation> {
                             item: selection_set,
                             data: self.data.as_deref(),
                             variables: self.variables.as_deref(),
+                            variable_definitions: None,
                             registry: &self.registry,
                         };
                         return self.query.resolve(&ctx).await;
@@ -109,6 +110,7 @@ impl<'a, Query, Mutation> QueryBuilder<'a, Query, Mutation> {
                             item: &query.selection_set,
                             data: self.data.as_deref(),
                             variables: self.variables.as_deref(),
+                            variable_definitions: Some(&query.variable_definitions),
                             registry: self.registry.clone(),
                         };
                         return self.query.resolve(&ctx).await;
@@ -122,6 +124,7 @@ impl<'a, Query, Mutation> QueryBuilder<'a, Query, Mutation> {
                             item: &mutation.selection_set,
                             data: self.data.as_deref(),
                             variables: self.variables.as_deref(),
+                            variable_definitions: Some(&mutation.variable_definitions),
                             registry: self.registry.clone(),
                         };
                         return self.mutation.resolve(&ctx).await;
diff --git a/src/types/enum.rs b/src/types/enum.rs
index 63ee0911..29f7c567 100644
--- a/src/types/enum.rs
+++ b/src/types/enum.rs
@@ -13,33 +13,21 @@ pub trait GQLEnum: GQLType + Sized + Eq + Send + Copy + Sized + 'static {
     fn items() -> &'static [GQLEnumItem<Self>];
 
     fn parse_enum(value: &Value) -> Option<Self> {
-        match value {
-            Value::Enum(s) => {
-                let items = Self::items();
-                for item in items {
-                    if item.name == s {
-                        return Some(item.value);
-                    }
-                }
-            }
-            _ => {}
-        }
-        None
-    }
+        let value = match value {
+            Value::Enum(s) => Some(s.as_str()),
+            Value::String(s) => Some(s.as_str()),
+            _ => None,
+        };
 
-    fn parse_json_enum(value: &serde_json::Value) -> Option<Self> {
-        match value {
-            serde_json::Value::String(s) => {
-                let items = Self::items();
-                for item in items {
-                    if item.name == s {
-                        return Some(item.value);
-                    }
+        value.and_then(|value| {
+            let items = Self::items();
+            for item in items {
+                if item.name == value {
+                    return Some(item.value);
                 }
             }
-            _ => {}
-        }
-        None
+            None
+        })
     }
 
     fn resolve_enum(&self) -> Result<serde_json::Value> {
diff --git a/src/types/list.rs b/src/types/list.rs
index 8a250ca6..966d833d 100644
--- a/src/types/list.rs
+++ b/src/types/list.rs
@@ -24,19 +24,6 @@ impl<T: GQLInputValue> GQLInputValue for Vec<T> {
             _ => None,
         }
     }
-
-    fn parse_from_json(value: &serde_json::Value) -> Option<Self> {
-        match value {
-            serde_json::Value::Array(values) => {
-                let mut result = Vec::new();
-                for value in values {
-                    result.push(GQLInputValue::parse_from_json(value)?);
-                }
-                Some(result)
-            }
-            _ => None,
-        }
-    }
 }
 
 #[async_trait::async_trait]
diff --git a/src/types/optional.rs b/src/types/optional.rs
index 865d12f1..497ce9f3 100644
--- a/src/types/optional.rs
+++ b/src/types/optional.rs
@@ -22,13 +22,6 @@ impl<T: GQLInputValue> GQLInputValue for Option<T> {
             _ => Some(GQLInputValue::parse(value)?),
         }
     }
-
-    fn parse_from_json(value: &serde_json::Value) -> Option<Self> {
-        match value {
-            serde_json::Value::Null => Some(None),
-            _ => Some(GQLInputValue::parse_from_json(value)?),
-        }
-    }
 }
 
 #[async_trait::async_trait]