Merge pull request #917 from bvanneerven/master

docs/en/src/SUMMARY.md

@@ -13,6 +13,7 @@
   - [Interface](define_interface.md)
   - [Union](define_union.md)
   - [InputObject](define_input_object.md)
+  - [OneofObject](define_one_of_object.md)
   - [Default value](default_value.md)
 - [Schema](define_schema.md)
   - [Query and Mutation](query_and_mutation.md)

docs/en/src/define_one_of_object.md

@@ -0,0 +1,36 @@
+# OneofObject
+
+A `OneofObject` is a special type of `InputObject`, in which only one of its fields must be set and is not-null.
+It is especially useful when you want a user to be able to choose between several potential input types.
+
+This feature is still an [RFC](https://github.com/graphql/graphql-spec/pull/825) and therefore not yet officially part of the GraphQL spec, but `Async-graphql` already supports it!
+
+```rust
+use async_graphql::*;
+
+#[derive(OneofObject)]
+enum UserBy {
+    Email(String),
+    RegistrationNumber(i64),
+    Address(Address)
+}
+
+#[derive(InputObject)]
+struct Address {
+    street: String,
+    house_number: String,
+    city: String,
+    zip: String,
+}
+
+struct Query {}
+
+#[Object]
+impl Query {
+    async fn search_users(&self, by: Vec<UserBy>) -> Vec<User> {
+        // ... Searches and returns a list of users ...
+    }
+}
+```
+
+As you can see, a `OneofObject` is represented by an `enum` in which each variant contains another `InputType`. This means that you can use [`InputObject`](define_input_object.md) as variant too.