Attribute for defining examples (#23)

schemars_derive/src/attr/mod.rs

@@ -16,7 +16,7 @@ pub struct Attrs {
     pub title: Option<String>,
     pub description: Option<String>,
     pub deprecated: bool,
-    // TODO pub example: Option<syn::Path>,
+    pub examples: Vec<syn::Path>,
 }
 
 #[derive(Debug)]
@@ -111,6 +111,12 @@ impl Attrs {
                     }
                 }
 
+                Meta(NameValue(m)) if m.path.is_ident("example") => {
+                    if let Ok(fun) = parse_lit_into_path(errors, attr_type, "example", &m.lit) {
+                        self.examples.push(fun)
+                    }
+                }
+
                 Meta(_meta_item) => {
                     // TODO uncomment this for 0.8.0 (breaking change)
                     //  https://github.com/GREsau/schemars/issues/18

schemars_derive/src/metadata.rs

@@ -3,13 +3,14 @@ use attr::Attrs;
 use proc_macro2::{Ident, Span, TokenStream};
 use quote::{ToTokens, TokenStreamExt};
 
-#[derive(Debug, Clone, Default)]
+#[derive(Debug, Clone)]
 pub struct SchemaMetadata<'a> {
     pub title: Option<&'a str>,
     pub description: Option<&'a str>,
     pub deprecated: bool,
     pub read_only: bool,
     pub write_only: bool,
+    pub examples: &'a [syn::Path],
     pub default: Option<TokenStream>,
 }
 
@@ -36,7 +37,10 @@ impl<'a> SchemaMetadata<'a> {
             title: attrs.title.as_ref().and_then(none_if_empty),
             description: attrs.description.as_ref().and_then(none_if_empty),
             deprecated: attrs.deprecated,
-            ..Default::default()
+            examples: &attrs.examples,
+            read_only: false,
+            write_only: false,
+            default: None,
         }
     }
 
@@ -80,6 +84,17 @@ impl<'a> SchemaMetadata<'a> {
             });
         }
 
+        if !self.examples.is_empty() {
+            let examples = self.examples.iter().map(|eg| {
+                quote! {
+                    schemars::_serde_json::value::to_value(#eg())
+                }
+            });
+            setters.push(quote! {
+                metadata.examples = vec![#(#examples),*].into_iter().flatten().collect();
+            });
+        }
+
         if let Some(default) = &self.default {
             setters.push(quote! {
                 metadata.default = #default.and_then(|d| schemars::_serde_json::value::to_value(d).ok());