add support for header-only responses

Author: lovasoa

src/render.rs

@@ -1,7 +1,7 @@
 use crate::templates::SplitTemplate;
 use crate::AppState;
 use actix_web::http::StatusCode;
-use actix_web::HttpResponseBuilder;
+use actix_web::{HttpResponse, HttpResponseBuilder};
 use anyhow::{bail, format_err, Context as AnyhowContext};
 use async_recursion::async_recursion;
 use handlebars::{BlockContext, Context, JsonValue, RenderError, Renderable};
@@ -86,6 +86,11 @@ impl<W: std::io::Write> HeaderContext<W> {
             http_response,
         })
     }
+
+    pub async fn close(mut self) -> anyhow::Result<(RenderContext<W>, HttpResponse)> {
+        let renderer = RenderContext::new(self.app_state, self.writer, JsonValue::Null).await?;
+        Ok((renderer, self.response.finish()))
+    }
 }
 
 fn get_object_str<'a>(json: &'a JsonValue, key: &str) -> Option<&'a str> {

src/webserver/http.rs

@@ -185,7 +185,16 @@ async fn build_response_header_and_stream<S: Stream<Item = DbItem>>(
             }
         }
     }
-    Err(ErrorInternalServerError("no SQL statements to execute"))
+    log::debug!("No SQL statements left to execute for the body of the response");
+    let (renderer, http_response) = head_context
+        .close()
+        .await
+        .map_err(ErrorInternalServerError)?;
+    Ok(ResponseWithWriter {
+        http_response,
+        renderer,
+        database_entries_stream: stream,
+    })
 }
 
 struct ResponseWithWriter<S> {