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fix: handle newlines in SSE events to prevent content truncation #21 #22

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fix: handle newlines in SSE events to prevent content truncation #21 #22

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15 changes: 11 additions & 4 deletions src/hyper/render.clj
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,8 @@
"Rendering pipeline.

Handles rendering hiccup to HTML and formatting Datastar SSE events."
(:require [dev.onionpancakes.chassis.core :as c]
(:require [clojure.string :as string]
[dev.onionpancakes.chassis.core :as c]
[hyper.context :as context]
[hyper.routes :as routes]
[hyper.state :as state]
Expand All @@ -27,10 +28,16 @@
event: datastar-patch-elements
data: elements <html content>

(blank line to end event)"
For multi-line HTML content, emits multiple 'data: elements' lines
that Datastar will concatenate. This prevents \n in HTML from
prematurely terminating the SSE event."
[html]
(str "event: datastar-patch-elements\n"
"data: elements " html "\n\n"))
(let [lines (string/split-lines html)]
(str "event: datastar-patch-elements\n"
(->> lines
(map (fn [line] (str "data: elements " line "\n")))
(apply str))
"\n")))

(defn mark-head-elements
"Add `{:data-hyper-head true}` to each top-level hiccup element in a
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16 changes: 15 additions & 1 deletion test/hyper/e2e_test.clj
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Expand Up @@ -578,8 +578,22 @@

(is (= "Live Reloaded!" (w/text-content "h1")))
(is (= "This content was hot-swapped"
(w/text-content "#reloaded-marker")))))
(w/text-content "#reloaded-marker"))))

;; Test that content with newlines renders correctly
(testing "Content with newlines preserved in route handler"
(alter-var-root #'*test-routes*
(constantly
[["/" {:name :home
:title "Newlines Test"
:get (fn [_]
[:div
[:textarea#newline-content "line1\nline2"]
[:pre#pre-content "code\nwith\n\nnew\n\nlines\n\n"]])}]]))
(w/navigate (str base-url "/"))
(wait-for-sse)
(is (= "line1\nline2" (w/text-content "#newline-content")))
(is (= "code\nwith\n\nnew\n\nlines\n\n" (w/text-content "#pre-content")))))
(finally
(close-browser! browser-info)))))

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19 changes: 18 additions & 1 deletion test/hyper/render_test.clj
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Original file line number Diff line number Diff line change
Expand Up @@ -38,7 +38,24 @@
(let [html "<span>test</span>"
fragment (render/format-datastar-fragment html)]
(is (.contains fragment html))
(is (.startsWith fragment "event: datastar-patch-elements\n")))))
(is (.startsWith fragment "event: datastar-patch-elements\n"))))

(testing "HTML with 2 newlines emits multiple data lines"
(let [html "<pre>code\nwith\nnewline</pre>"
fragment (render/format-datastar-fragment html)]
(is (= 3 (count (re-seq #"data: elements" fragment))))
(is (.contains fragment "<pre>code"))
(is (.contains fragment "with"))
(is (.contains fragment "newline</pre>"))
(is (.endsWith fragment "\n\n"))))

(testing "HTML with double newlines emits multiple data lines"
(let [html "<textarea>line1\n\nline2</textarea>"
fragment (render/format-datastar-fragment html)]
(is (= 3 (count (re-seq #"data: elements" fragment))))
(is (.contains fragment "<textarea>line1"))
(is (.contains fragment "line2</textarea>"))
(is (.endsWith fragment "\n\n")))))

(deftest test-render-tab
(testing "render-tab returns nil when no render-fn is registered"
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