Option to preserve formatting

schemars/tests/docs.rs

@@ -51,6 +51,16 @@ pub enum MyEnum {
     },
 }
 
+/// This
+/// is
+/// not
+///                         a
+/// single
+/// line.
+#[derive(JsonSchema)]
+#[schemars_preserve_doc_formatting]
+pub struct MyPreserveFormattingStruct;
+
 #[test]
 fn doc_comments_struct() -> TestResult {
     test_default_generated_schema::<MyStruct>("doc_comments_struct")
@@ -67,6 +77,11 @@ fn doc_comments_enum() -> TestResult {
     test_default_generated_schema::<MyEnum>("doc_comments_enum")
 }
 
+#[test]
+fn doc_comments_preserve_formatting() -> TestResult {
+    test_default_generated_schema::<MyPreserveFormattingStruct>("doc_comments_preserve_formatting")
+}
+
 /// # OverrideDocs struct
 /// This description should be overridden
 #[derive(Debug, JsonSchema)]

schemars/tests/expected/doc_comments_preserve_formatting.json

@@ -0,0 +1,6 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "MyPreserveFormattingStruct",
+  "description": "This\nis\nnot\n                        a\nsingle\nline.",
+  "type": "null"
+}

schemars_derive/src/attr/doc.rs

@@ -1,24 +1,34 @@
 use syn::{Attribute, Lit::Str, Meta::NameValue, MetaNameValue};
 
 pub fn get_title_and_desc_from_doc(attrs: &[Attribute]) -> (Option<String>, Option<String>) {
-    let doc = match get_doc(attrs) {
+    let preserve_formatting = should_preserve_formatting(attrs);
+
+    let doc = match get_doc(attrs, preserve_formatting) {
         None => return (None, None),
         Some(doc) => doc,
     };
 
-    if doc.starts_with('#') {
+    let (title, mut maybe_desc) = if doc.starts_with('#') {
         let mut split = doc.splitn(2, '\n');
         let title = split
             .next()
             .unwrap()
             .trim_start_matches('#')
             .trim()
             .to_owned();
-        let maybe_desc = split.next().and_then(merge_description_lines);
-        (none_if_empty(title), maybe_desc)
+        (none_if_empty(title), split.next().map(ToOwned::to_owned))
     } else {
-        (None, merge_description_lines(&doc))
+        (None, Some(doc))
+    };
+
+    if !preserve_formatting {
+        maybe_desc = maybe_desc
+            .as_ref()
+            .map(String::as_str)
+            .and_then(merge_description_lines);
     }
+
+    (title, maybe_desc)
 }
 
 fn merge_description_lines(doc: &str) -> Option<String> {
@@ -31,7 +41,13 @@ fn merge_description_lines(doc: &str) -> Option<String> {
     none_if_empty(desc)
 }
 
-fn get_doc(attrs: &[Attribute]) -> Option<String> {
+fn should_preserve_formatting(attrs: &[Attribute]) -> bool {
+    attrs
+        .iter()
+        .any(|attr| attr.path.is_ident("schemars_preserve_doc_formatting"))
+}
+
+fn get_doc(attrs: &[Attribute], preserve_formatting: bool) -> Option<String> {
     let doc = attrs
         .iter()
         .filter_map(|attr| {
@@ -46,13 +62,19 @@ fn get_doc(attrs: &[Attribute]) -> Option<String> {
 
             None
         })
-        .collect::<Vec<_>>()
-        .iter()
-        .flat_map(|a| a.split('\n'))
-        .map(str::trim)
-        .skip_while(|s| *s == "")
-        .collect::<Vec<_>>()
-        .join("\n");
+        .collect::<Vec<_>>();
+
+    let doc = if !preserve_formatting {
+        doc.iter()
+            .flat_map(|a| a.split('\n'))
+            .map(str::trim)
+            .skip_while(|s| *s == "")
+            .collect::<Vec<_>>()
+            .join("\n")
+    } else {
+        doc.join("\n")
+    };
+
     none_if_empty(doc)
 }
 

schemars_derive/src/lib.rs

@@ -12,7 +12,10 @@ mod schema_exprs;
 use ast::*;
 use proc_macro2::TokenStream;
 
-#[proc_macro_derive(JsonSchema, attributes(schemars, serde))]
+#[proc_macro_derive(
+    JsonSchema,
+    attributes(schemars, serde, schemars_preserve_doc_formatting)
+)]
 pub fn derive_json_schema_wrapper(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     let input = parse_macro_input!(input as syn::DeriveInput);
     derive_json_schema(input).into()