Add example for handling custom serialization

docs/_includes/example.md

@@ -9,6 +9,6 @@
 <summary>Click to see the output JSON schema...</summary>
 
 ```json
-{% include {{ output }} %}
+{% include {{ output }} -%}
 ```
 </details>

docs/_includes/examples/custom_serialization.rs

@@ -0,0 +1,48 @@
+use schemars::{schema_for, JsonSchema};
+use serde::{Deserialize, Serialize};
+
+// `int_as_string` and `bool_as_string` use the schema for `String`.
+#[derive(Default, Deserialize, Serialize, JsonSchema)]
+pub struct MyStruct {
+    #[serde(default = "eight", with = "as_string")]
+    #[schemars(with = "String")]
+    pub int_as_string: i32,
+    #[serde(default = "eight")]
+    pub int_normal: i32,
+    #[serde(default, with = "as_string")]
+    #[schemars(with = "String")]
+    pub bool_as_string: bool,
+    #[serde(default)]
+    pub bool_normal: bool,
+}
+
+fn eight() -> i32 {
+    8
+}
+
+// This module serializes values as strings
+mod as_string {
+    use serde::{de::Error, Deserialize, Deserializer, Serializer};
+
+    pub fn serialize<T, S>(value: &T, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        T: std::fmt::Display,
+        S: Serializer,
+    {
+        serializer.collect_str(value)
+    }
+
+    pub fn deserialize<'de, T, D>(deserializer: D) -> Result<T, D::Error>
+    where
+        T: std::str::FromStr,
+        D: Deserializer<'de>,
+    {
+        let string = String::deserialize(deserializer)?;
+        string.parse().map_err(|_| D::Error::custom("Input was not valid"))
+    }
+}
+
+fn main() {
+    let schema = schema_for!(MyStruct);
+    println!("{}", serde_json::to_string_pretty(&schema).unwrap());
+}

docs/_includes/examples/custom_serialization.schema.json

@@ -0,0 +1,24 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "MyStruct",
+  "type": "object",
+  "properties": {
+    "bool_as_string": {
+      "default": "false",
+      "type": "string"
+    },
+    "bool_normal": {
+      "default": false,
+      "type": "boolean"
+    },
+    "int_as_string": {
+      "default": "8",
+      "type": "string"
+    },
+    "int_normal": {
+      "default": 8,
+      "type": "integer",
+      "format": "int32"
+    }
+  }
+}

docs/_sass/overrides.scss

@@ -52,4 +52,8 @@ code {
 details summary {
     display: list-item;
     cursor: pointer;
+}
+
+details {
+    margin-bottom: 0.8rem;
 }

docs/examples/6-doc_comments.md

@@ -2,7 +2,7 @@
 layout: default
 title: Doc Comments
 parent: Examples
-nav_order: 5
+nav_order: 6
 summary: Giving schemas a custom title and/or description using doc comments.
 ---
 

docs/examples/7-custom_serialization.md

@@ -0,0 +1,20 @@
+---
+layout: default
+title: Custom Serialization
+parent: Examples
+nav_order: 7
+summary: >-
+  If a field has a #[serde(with = "path")] attribute where "path" is not a type that implements JsonSchema,
+  then in order to derive JsonSchema on the type, it must also have a #[schemars(with = "Type")] attribute,
+  where "Type" implements JsonSchema.
+---
+
+# Deriving JsonSchema with Fields Using Custom Serialization
+
+Serde allows you to change how a field is (de)serialized by setting a [`#[serde(with = "path")]`](https://serde.rs/field-attrs.html#with) attribute, where `$path::serialize` and `$path::deserialize` must be functions with the correct signature. Schemars supports the same attribute, but `path` must be a type implementing `JsonSchema`.
+
+In order to derive `JsonSchema` on a type which includes a `#[serde(with = "path")]` attribute where `path` is not  a type implementing `JsonSchema`, you'll need to override it with a suitable `#[schemars(with = "Type")]` attribute.
+
+{% include example.md name="custom_serialization" %}
+
+Note that the `default` values in the schema are serialized as strings where appropriate.