fix: 🐛 allowed build state to return ErrorCause for incremental generation

Author: arctic-hen7

examples/showcase/app/src/pages/index.rs

@@ -1,4 +1,5 @@
 use perseus::template::Template;
+use perseus::errors::ErrorCause;
 use serde::{Deserialize, Serialize};
 use sycamore::prelude::{component, template, GenericNode, Template as SycamoreTemplate};
 
@@ -21,7 +22,7 @@ pub fn get_page<G: GenericNode>() -> Template<G> {
         .template(template_fn())
 }
 
-pub async fn get_static_props(_path: String) -> Result<String, String> {
+pub async fn get_static_props(_path: String) -> Result<String, (String, ErrorCause)> {
     Ok(serde_json::to_string(&IndexPageProps {
         greeting: "Hello World!".to_string(),
     })

examples/showcase/app/src/pages/post.rs

@@ -1,4 +1,5 @@
 use perseus::template::Template;
+use perseus::errors::ErrorCause;
 use serde::{Deserialize, Serialize};
 use sycamore::prelude::{component, template, GenericNode, Template as SycamoreTemplate};
 
@@ -30,7 +31,11 @@ pub fn get_page<G: GenericNode>() -> Template<G> {
         .template(template_fn())
 }
 
-pub async fn get_static_props(path: String) -> Result<String, String> {
+pub async fn get_static_props(path: String) -> Result<String, (String, ErrorCause)> {
+    // This path is illegal, and can't be rendered
+    if path == "post/tests" {
+        return Err(("illegal page".to_string(), ErrorCause::Client(Some(404))))
+    }
     // This is just an example
     let title = urlencoding::decode(&path).unwrap();
     let content = format!(

examples/showcase/app/src/pages/time.rs

@@ -1,4 +1,5 @@
 use perseus::template::Template;
+use perseus::errors::ErrorCause;
 use serde::{Deserialize, Serialize};
 use sycamore::prelude::{component, template, GenericNode, Template as SycamoreTemplate};
 
@@ -24,7 +25,7 @@ pub fn get_page<G: GenericNode>() -> Template<G> {
         .build_paths_fn(Box::new(get_build_paths))
 }
 
-pub async fn get_build_state(_path: String) -> Result<String, String> {
+pub async fn get_build_state(_path: String) -> Result<String, (String, ErrorCause)> {
     Ok(serde_json::to_string(&TimePageProps {
         time: format!("{:?}", std::time::SystemTime::now()),
     })

examples/showcase/app/src/pages/time_root.rs

@@ -1,4 +1,5 @@
 use perseus::template::Template;
+use perseus::errors::ErrorCause;
 use serde::{Deserialize, Serialize};
 use sycamore::prelude::{component, template, GenericNode, Template as SycamoreTemplate};
 
@@ -24,7 +25,7 @@ pub fn get_page<G: GenericNode>() -> Template<G> {
         .build_state_fn(Box::new(get_build_state))
 }
 
-pub async fn get_build_state(_path: String) -> Result<String, String> {
+pub async fn get_build_state(_path: String) -> Result<String, (String, ErrorCause)> {
     Ok(serde_json::to_string(&TimePageProps {
         time: format!("{:?}", std::time::SystemTime::now()),
     })

src/template.rs

@@ -87,7 +87,8 @@ macro_rules! make_async_trait {
 
 // A series of asynchronous closure traits that prevent the user from having to pin their functions
 make_async_trait!(GetBuildPathsFnType, StringResult<Vec<String>>);
-make_async_trait!(GetBuildStateFnType, StringResult<String>, path: String);
+// The build state strategy needs an error cause if it's invoked from incremental
+make_async_trait!(GetBuildStateFnType, StringResultWithCause<String>, path: String);
 make_async_trait!(
     GetRequestStateFnType,
     StringResultWithCause<String>,
@@ -192,10 +193,10 @@ impl<G: GenericNode> Template<G> {
             let res = get_build_state.call(path).await;
             match res {
                 Ok(res) => Ok(res),
-                Err(err) => bail!(ErrorKind::RenderFnFailed(
+                Err((err, cause)) => bail!(ErrorKind::RenderFnFailed(
                     "get_build_state".to_string(),
                     self.get_path(),
-                    ErrorCause::Server(None),
+                    cause,
                     err
                 )),
             }