Add some docs

docs/en/src/SUMMARY.md

@@ -25,7 +25,6 @@
     - [Actix-web](integrations_to_actix_web.md)
 - [Advanced topics](advanced_topics.md)
     - [Custom scalars](custom_scalars.md)
-    - [Custom input value validators](custom_input_value_validators.md)
     - [Custom extensions](custom_extensions.md)
     - [Custom subscription transport](custom_subscription_transport.md)
     - [Apollo Federation](apollo_federation.md)

docs/en/src/custom_input_value_validators.md

@@ -1 +0,0 @@
-# Custom input value validators

docs/zh-CN/src/SUMMARY.md

@@ -24,7 +24,6 @@
     - [Actix-web](integrations_to_actix_web.md)
 - [高级主题](advanced_topics.md)
     - [自定义标量](custom_scalars.md)
-    - [自定义输入值校验器](custom_input_value_validators.md)
     - [自定义扩展](custom_extensions.md)
     - [自定义订阅传输协议](custom_subscription_transport.md)
     - [Apollo Federation集成](apollo_federation.md)

docs/zh-CN/src/custom_input_value_validators.md

@@ -1 +0,0 @@
-# 自定义输入值校验器

docs/zh-CN/src/input_value_validators.md

@@ -37,4 +37,30 @@ impl Query {
     } {
     }
 }
-```
+```
+
+## 自定义校验器
+
+```rust
+struct MustBeZero {}
+
+impl InputValueValidator for InputValueValidator {
+    fn is_valid(&self, value: &Value) -> Option<String> {
+        if let Value::Int(n) = value {
+            if n.as_i64().unwrap() != 0 {
+                // 校验失败
+                Some(format!(
+                    "the value is {}, but must be zero",
+                    n.as_i64().unwrap(),
+                ))
+            } else {
+                // 校验通过
+                None
+            }
+        } else {
+            // 类型不匹配，直接返回None，内置校验器会发现这个错误
+            None
+        }
+    }
+}
+```

src/validators/int_validators.rs

@@ -72,7 +72,7 @@ impl InputValueValidator for IntGreaterThan {
                 None
             }
         } else {
-            Some("expected type \"Int\"".to_string())
+            None
         }
     }
 }
@@ -92,7 +92,7 @@ impl InputValueValidator for IntNonZero {
                 None
             }
         } else {
-            Some("expected type \"Int\"".to_string())
+            None
         }
     }
 }

src/validators/list_validators.rs

@@ -20,7 +20,7 @@ impl InputValueValidator for ListMinLength {
                 None
             }
         } else {
-            Some("expected type \"List\"".to_string())
+            None
         }
     }
 }