allow plugins to alter request/response

api_tests/src/post.spec.ts

@@ -764,13 +764,14 @@ test("Fetch post with redirect", async () => {
   expect(gammaPost2.post).toBeDefined();
 });
 
-test("Create a post", async () => {
+test.only("Plugin test", async () => {
   let community = await createCommunity(epsilon);
   let postRes = createPost(
     epsilon,
     community.community_view.community.id,
     "https://example.com/",
-    "plugin should block this",
+    "body",
+    "foobar",
   );
-  await expect(postRes).rejects.toStrictEqual(Error("plugin_error"));
+  expect((await postRes).post_view.post.name).toBe("Hello plugin!");
 });

crates/api_crud/src/post/create.rs

@@ -55,10 +55,12 @@ use webmention::{Webmention, WebmentionError};
 
 #[tracing::instrument(skip(context))]
 pub async fn create_post(
-  data: Json<CreatePost>,
+  mut data: Json<CreatePost>,
   context: Data<LemmyContext>,
   local_user_view: LocalUserView,
 ) -> LemmyResult<Json<PostResponse>> {
+  plugin_hook("api_before_create_post", &mut (*data))?;
+
   let local_site = LocalSite::read(&mut context.pool()).await?;
 
   honeypot_check(&data.honeypot)?;
@@ -126,8 +128,6 @@ pub async fn create_post(
     }
   };
 
-  plugin_hook("api_before_create_post", data.clone())?;
-
   let post_form = PostInsertForm::builder()
     .name(data.name.trim().to_string())
     .url(url)
@@ -161,8 +161,6 @@ pub async fn create_post(
   .await
   .with_lemmy_type(LemmyErrorType::CouldntCreatePost)?;
 
-  plugin_hook("api_after_create_post", updated_post.clone())?;
-
   generate_post_link_metadata(
     updated_post.clone(),
     custom_thumbnail,
@@ -207,11 +205,17 @@ pub async fn create_post(
     }
   };
 
-  build_post_response(&context, community_id, &local_user_view.person, post_id).await
+  let mut res = build_post_response(&context, community_id, &local_user_view.person, post_id)
+    .await?
+    .0;
+
+  plugin_hook("api_after_create_post", &mut res)?;
+  Ok(Json(res))
 }
 
 fn load_plugins() -> LemmyResult<Plugin> {
   // TODO: make dir configurable via env var
+  // TODO: should only read fs once at startup for performance
   let plugin_paths = read_dir("example_plugin")?;
 
   let mut wasm_files = vec![];
@@ -226,13 +230,20 @@ fn load_plugins() -> LemmyResult<Plugin> {
   Ok(plugin)
 }
 
-fn plugin_hook<T: Serialize>(name: &'static str, data: T) -> LemmyResult<()> {
+fn plugin_hook<T: Serialize + for<'de> serde::Deserialize<'de> + Clone>(
+  name: &'static str,
+  data: &mut T,
+) -> LemmyResult<()> {
   let mut plugin = load_plugins()?;
   if plugin.function_exists(name) {
-    let res = plugin
-      .call::<extism_convert::Json<T>, &str>(name, data.into())
-      .map_err(|e| LemmyErrorType::PluginError(e.to_string()));
-    println!("{}", res?);
+    *data = plugin
+      .call::<extism_convert::Json<T>, extism_convert::Json<T>>(name, (*data).clone().into())
+      .map_err(|e| {
+        dbg!(&e);
+        LemmyErrorType::PluginError(e.to_string())
+      })?
+      .0
+      .into();
   }
   Ok(())
 }

example_plugin/main.go

@@ -2,13 +2,18 @@ package main
 
 import (
 	"github.com/extism/go-pdk"
-	"errors"
 )
 
 type CreatePost struct {
 	Name string `json:"name"`
-	Body string `json:"body"`
-	// skipping other fields for now
+	Body *string `json:"body,omitempty"`
+	Community_id int32 `json:"community_id"`
+	Url *string `json:"url,omitempty"`
+	Alt_text *string `json:"alt_text,omitempty"`
+	Honeypot *string `json:"honeypot,omitempty"`
+	Nsfw *bool `json:"nsfw,omitempty"`
+	Language_id *int32 `json:"language_id,omitempty"`
+	Custom_thumbnail *string `json:"custom_thumbnail,omitempty"`
   }
 
 //export api_before_create_post
@@ -20,12 +25,15 @@ func api_before_create_post() int32 {
 		pdk.SetError(err)
 		return 1
 	}
-	if params.Body == "plugin should block this" {
-		pdk.SetError(errors.New("blocked by plugin"))
+	if params.Name == "foobar" {
+		params.Name = "Hello plugin!"
+	}
+	// use json output helper, which automatically marshals your struct to the plugin output
+	err = pdk.OutputJSON(params)
+	if err != nil {
+		pdk.SetError(err)
 		return 1
 	}
-	greeting := `Created post "` + params.Name + `"!`
-	pdk.OutputString(greeting)
 	return 0
 }