diff --git a/README.md b/README.md
index 3b527528..8c537fb8 100644
--- a/README.md
+++ b/README.md
@@ -51,7 +51,7 @@
     - [ ] Fragments
     - [ ] Inline fragments
     - [X] Operation name
-    - [ ] Variables
+    - [X] Variables
     - [ ] Directives
     - [ ] Schema
 
diff --git a/async-graphql-derive/src/enum.rs b/async-graphql-derive/src/enum.rs
index 22bd84ed..9b60f1eb 100644
--- a/async-graphql-derive/src/enum.rs
+++ b/async-graphql-derive/src/enum.rs
@@ -67,9 +67,13 @@ pub fn generate(enum_args: &args::Enum, input: &DeriveInput) -> Result<TokenStre
         }
 
         impl async_graphql::GQLInputValue for #ident {
-            fn parse(value: graphql_parser::query::Value) -> Result<Self> {
+            fn parse(value: async_graphql::Value) -> Result<Self> {
                 Self::parse_enum(value)
             }
+
+            fn parse_from_json(value: async_graphql::serde_json::Value) -> Result<Self> {
+                Self::parse_json_enum(value)
+            }
         }
 
         #[async_graphql::async_trait::async_trait]
diff --git a/async-graphql-derive/src/input_object.rs b/async-graphql-derive/src/input_object.rs
index 39624ab1..4d8c7759 100644
--- a/async-graphql-derive/src/input_object.rs
+++ b/async-graphql-derive/src/input_object.rs
@@ -16,7 +16,9 @@ pub fn generate(object_args: &args::Object, input: &DeriveInput) -> Result<Token
         .unwrap_or_else(|| ident.to_string());
 
     let mut get_fields = Vec::new();
+    let mut get_json_fields = Vec::new();
     let mut fields = Vec::new();
+
     for field in &s.fields {
         let field_args = args::InputField::parse(&field.attrs)?;
         let ident = field.ident.as_ref().unwrap();
@@ -25,6 +27,9 @@ pub fn generate(object_args: &args::Object, input: &DeriveInput) -> Result<Token
         get_fields.push(quote! {
             let #ident:#ty = async_graphql::GQLInputValue::parse(obj.remove(#name).unwrap_or(async_graphql::Value::Null))?;
         });
+        get_json_fields.push(quote! {
+            let #ident:#ty = async_graphql::GQLInputValue::parse_from_json(obj.remove(#name).unwrap_or(async_graphql::serde_json::Value::Null))?;
+        });
         fields.push(ident);
     }
 
@@ -49,6 +54,18 @@ pub fn generate(object_args: &args::Object, input: &DeriveInput) -> Result<Token
                     }.into())
                 }
             }
+
+            fn parse_from_json(value: async_graphql::serde_json::Value) -> async_graphql::Result<Self> {
+                if let async_graphql::serde_json::Value::Object(mut obj) = value {
+                    #(#get_json_fields)*
+                    Ok(Self { #(#fields),* })
+                } else {
+                    Err(async_graphql::QueryError::ExpectedJsonType {
+                        expect: Self::type_name(),
+                        actual: value,
+                    }.into())
+                }
+            }
         }
 
         impl async_graphql::GQLInputObject for #ident {}
diff --git a/async-graphql-derive/src/object.rs b/async-graphql-derive/src/object.rs
index a71a4e93..ffc3593c 100644
--- a/async-graphql-derive/src/object.rs
+++ b/async-graphql-derive/src/object.rs
@@ -62,7 +62,8 @@ pub fn generate(object_args: &args::Object, input: &DeriveInput) -> Result<Token
                     let ctx_obj = ctx_field.with_item(&field.selection_set);
                     let value = obj.resolve(&ctx_obj).await.
                         map_err(|err| err.with_position(field.position))?;
-                    result.insert(#field_name.to_string(), value.into());
+                    let name = field.alias.clone().unwrap_or_else(|| field.name.clone());
+                    result.insert(name, value.into());
                     continue;
                 }
             });
@@ -105,7 +106,8 @@ pub fn generate(object_args: &args::Object, input: &DeriveInput) -> Result<Token
                         async_graphql::graphql_parser::query::Selection::Field(field) => {
                             let ctx_field = ctx.with_item(field);
                             if field.name.as_str() == "__typename" {
-                                result.insert("__typename".to_string(), #gql_typename.into());
+                                let name = field.alias.clone().unwrap_or_else(|| field.name.clone());
+                                result.insert(name, #gql_typename.into());
                                 continue;
                             }
                             #(#resolvers)*
diff --git a/src/context.rs b/src/context.rs
index 3d227516..3ace3f84 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -6,7 +6,7 @@ use std::collections::HashMap;
 use std::hash::BuildHasherDefault;
 use std::ops::{Deref, DerefMut};
 
-#[derive(Serialize, Deserialize, Default)]
+#[derive(Default)]
 pub struct Variables(HashMap<String, serde_json::Value>);
 
 impl Deref for Variables {
@@ -78,28 +78,25 @@ impl<'a> Context<'a, &'a Field> {
             .iter()
             .find(|(n, _)| n == name)
             .map(|(_, v)| v)
-            .cloned()
-            .unwrap_or(Value::Null);
-        let value = match (value, &self.variables) {
-            (Value::Variable(name), Some(vars)) => match vars.get(&name).cloned() {
-                Some(value) => value,
-                None => {
-                    return Err(QueryError::VarNotDefined {
-                        var_name: name.clone(),
-                    }
-                    .into());
+            .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)
+                        .map_err(|err| err.with_position(self.item.position))?;
+                    return Ok(res);
                 }
-            },
-            (Value::Variable(name), None) => {
-                return Err(QueryError::VarNotDefined {
-                    var_name: name.clone(),
-                }
-                .into());
             }
-            (value, _) => value,
+
+            return Err(QueryError::VarNotDefined {
+                var_name: var_name.clone(),
+            }
+            .into());
         };
-        let res =
-            GQLInputValue::parse(value).map_err(|err| err.with_position(self.item.position))?;
+
+        let res = GQLInputValue::parse(value.unwrap_or(Value::Null))
+            .map_err(|err| err.with_position(self.item.position))?;
         Ok(res)
     }
 }
diff --git a/src/datetime.rs b/src/datetime.rs
index 0147cf3e..02530a08 100644
--- a/src/datetime.rs
+++ b/src/datetime.rs
@@ -1,4 +1,5 @@
-use crate::{QueryError, Scalar, Result, Value};
+use crate::{QueryError, Result, Scalar, Value};
+use anyhow::Error;
 use chrono::{DateTime, TimeZone, Utc};
 
 impl Scalar for DateTime<Utc> {
@@ -19,6 +20,19 @@ impl Scalar for DateTime<Utc> {
         }
     }
 
+    fn parse_from_json(value: serde_json::Value) -> Result<Self> {
+        match value {
+            serde_json::Value::String(s) => Ok(Utc.datetime_from_str(&s, "%+")?),
+            _ => {
+                return Err(QueryError::ExpectedJsonType {
+                    expect: Self::type_name().to_string(),
+                    actual: value,
+                }
+                .into())
+            }
+        }
+    }
+
     fn into_json(self) -> Result<serde_json::Value> {
         Ok(self.to_rfc3339().into())
     }
diff --git a/src/enum.rs b/src/enum.rs
index cd594dd5..27a9baa7 100644
--- a/src/enum.rs
+++ b/src/enum.rs
@@ -1,4 +1,4 @@
-use crate::{QueryError, GQLType, Result};
+use crate::{GQLType, QueryError, Result};
 use graphql_parser::query::Value;
 
 #[doc(hidden)]
@@ -38,6 +38,31 @@ pub trait GQLEnum: GQLType + Sized + Eq + Send + Copy + Sized + 'static {
         }
     }
 
+    fn parse_json_enum(value: serde_json::Value) -> Result<Self> {
+        match value {
+            serde_json::Value::String(s) => {
+                let items = Self::items();
+                for item in items {
+                    if item.name == s {
+                        return Ok(item.value);
+                    }
+                }
+                Err(QueryError::InvalidEnumValue {
+                    enum_type: Self::type_name(),
+                    value: s,
+                }
+                .into())
+            }
+            _ => {
+                return Err(QueryError::ExpectedJsonType {
+                    expect: Self::type_name(),
+                    actual: value,
+                }
+                .into())
+            }
+        }
+    }
+
     fn resolve_enum(self) -> Result<serde_json::Value> {
         let items = Self::items();
         for item in items {
diff --git a/src/error.rs b/src/error.rs
index a0eb58b3..50ae0231 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -15,6 +15,12 @@ pub enum QueryError {
     #[error("Expected type \"{expect}\", found {actual}.")]
     ExpectedType { expect: String, actual: Value },
 
+    #[error("Expected type \"{expect}\", found {actual}.")]
+    ExpectedJsonType {
+        expect: String,
+        actual: serde_json::Value,
+    },
+
     #[error("Cannot query field \"{field_name}\" on type \"{object}\".")]
     FieldNotFound {
         field_name: String,
diff --git a/src/lib.rs b/src/lib.rs
index 325f8bf9..bf011b00 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -32,8 +32,6 @@
 
 #[macro_use]
 extern crate thiserror;
-#[macro_use]
-extern crate serde_derive;
 
 mod context;
 mod r#enum;
diff --git a/src/scalar.rs b/src/scalar.rs
index e71abd4e..15c2d13d 100644
--- a/src/scalar.rs
+++ b/src/scalar.rs
@@ -1,10 +1,12 @@
 use crate::r#type::{GQLInputValue, GQLOutputValue, GQLType};
 use crate::{ContextSelectionSet, QueryError, Result};
+use anyhow::Error;
 use graphql_parser::query::Value;
 
 pub trait Scalar: Sized + Send {
     fn type_name() -> &'static str;
     fn parse(value: Value) -> Result<Self>;
+    fn parse_from_json(value: serde_json::Value) -> Result<Self>;
     fn into_json(self) -> Result<serde_json::Value>;
 }
 
@@ -18,6 +20,10 @@ impl<T: Scalar> GQLInputValue for T {
     fn parse(value: Value) -> Result<Self> {
         T::parse(value)
     }
+
+    fn parse_from_json(value: serde_json::Value) -> Result<Self> {
+        T::parse_from_json(value)
+    }
 }
 
 #[async_trait::async_trait]
@@ -48,6 +54,20 @@ macro_rules! impl_integer_scalars {
                 }
             }
 
+            fn parse_from_json(value: serde_json::Value) -> Result<Self> {
+                match value {
+                    serde_json::Value::Number(n) if n.is_i64() => Ok(n.as_i64().unwrap() as Self),
+                    serde_json::Value::Number(n) => Ok(n.as_f64().unwrap() as Self),
+                    _ => {
+                        return Err(QueryError::ExpectedJsonType {
+                            expect: <Self as GQLType>::type_name().to_string(),
+                            actual: value,
+                        }
+                        .into())
+                    }
+                }
+            }
+
             fn into_json(self) -> Result<serde_json::Value> {
                 Ok(self.into())
             }
@@ -80,6 +100,19 @@ macro_rules! impl_float_scalars {
                 }
             }
 
+            fn parse_from_json(value: serde_json::Value) -> Result<Self> {
+                match value {
+                    serde_json::Value::Number(n) => Ok(n.as_f64().unwrap() as Self),
+                    _ => {
+                        return Err(QueryError::ExpectedJsonType {
+                            expect: <Self as GQLType>::type_name().to_string(),
+                            actual: value,
+                        }
+                        .into())
+                    }
+                }
+            }
+
             fn into_json(self) -> Result<serde_json::Value> {
                 Ok(self.into())
             }
@@ -100,7 +133,20 @@ impl Scalar for String {
             Value::String(s) => Ok(s),
             _ => {
                 return Err(QueryError::ExpectedType {
-                    expect: <Self as Scalar>::type_name().to_string(),
+                    expect: <Self as GQLType>::type_name().to_string(),
+                    actual: value,
+                }
+                .into())
+            }
+        }
+    }
+
+    fn parse_from_json(value: serde_json::Value) -> Result<Self> {
+        match value {
+            serde_json::Value::String(s) => Ok(s),
+            _ => {
+                return Err(QueryError::ExpectedJsonType {
+                    expect: <Self as GQLType>::type_name().to_string(),
                     actual: value,
                 }
                 .into())
@@ -123,7 +169,20 @@ impl Scalar for bool {
             Value::Boolean(n) => Ok(n),
             _ => {
                 return Err(QueryError::ExpectedType {
-                    expect: <Self as Scalar>::type_name().to_string(),
+                    expect: <Self as GQLType>::type_name().to_string(),
+                    actual: value,
+                }
+                .into())
+            }
+        }
+    }
+
+    fn parse_from_json(value: serde_json::Value) -> Result<Self> {
+        match value {
+            serde_json::Value::Bool(n) => Ok(n),
+            _ => {
+                return Err(QueryError::ExpectedJsonType {
+                    expect: <Self as GQLType>::type_name().to_string(),
                     actual: value,
                 }
                 .into())
diff --git a/src/type.rs b/src/type.rs
index 662e9a0c..2405739c 100644
--- a/src/type.rs
+++ b/src/type.rs
@@ -1,4 +1,5 @@
 use crate::{ContextSelectionSet, ErrorWithPosition, QueryError, Result};
+use anyhow::Error;
 use graphql_parser::query::Value;
 
 #[doc(hidden)]
@@ -9,6 +10,7 @@ pub trait GQLType {
 #[doc(hidden)]
 pub trait GQLInputValue: GQLType + Sized {
     fn parse(value: Value) -> Result<Self>;
+    fn parse_from_json(value: serde_json::Value) -> Result<Self>;
 }
 
 #[doc(hidden)]
@@ -42,6 +44,25 @@ impl<T: GQLInputValue> GQLInputValue for Vec<T> {
             }
         }
     }
+
+    fn parse_from_json(value: serde_json::Value) -> Result<Self> {
+        match value {
+            serde_json::Value::Array(values) => {
+                let mut result = Vec::new();
+                for value in values {
+                    result.push(GQLInputValue::parse_from_json(value)?);
+                }
+                Ok(result)
+            }
+            _ => {
+                return Err(QueryError::ExpectedJsonType {
+                    expect: Self::type_name(),
+                    actual: value,
+                }
+                .into())
+            }
+        }
+    }
 }
 
 #[async_trait::async_trait]
@@ -68,6 +89,13 @@ impl<T: GQLInputValue> GQLInputValue for Option<T> {
             _ => Ok(Some(GQLInputValue::parse(value)?)),
         }
     }
+
+    fn parse_from_json(value: serde_json::Value) -> Result<Self> {
+        match value {
+            serde_json::Value::Null => Ok(None),
+            _ => Ok(Some(GQLInputValue::parse_from_json(value)?)),
+        }
+    }
 }
 
 #[async_trait::async_trait]
diff --git a/src/uuid.rs b/src/uuid.rs
index a71f9dfa..af7d2775 100644
--- a/src/uuid.rs
+++ b/src/uuid.rs
@@ -1,4 +1,5 @@
-use crate::{QueryError, Scalar, Result, Value};
+use crate::{QueryError, Result, Scalar, Value};
+use anyhow::Error;
 use uuid::Uuid;
 
 impl Scalar for Uuid {
@@ -19,6 +20,19 @@ impl Scalar for Uuid {
         }
     }
 
+    fn parse_from_json(value: serde_json::Value) -> Result<Self> {
+        match value {
+            serde_json::Value::String(s) => Ok(Uuid::parse_str(&s)?),
+            _ => {
+                return Err(QueryError::ExpectedJsonType {
+                    expect: Self::type_name().to_string(),
+                    actual: value,
+                }
+                .into())
+            }
+        }
+    }
+
     fn into_json(self) -> Result<serde_json::Value> {
         Ok(self.to_string().into())
     }