it actually works

posthog/api/site_app.py

@@ -7,6 +7,9 @@
 from statshog.defaults.django import statsd
 
 from posthog.exceptions import generate_exception_response
+from posthog.hogql import ast
+from posthog.hogql.compiler.javascript import create_javascript
+from posthog.hogql.parser import parse_string_template
 from posthog.logging.timing import timed
 from posthog.plugins.site import get_site_config_from_schema, get_transpiled_site_source
 
@@ -22,7 +25,21 @@ def get_site_app(request: HttpRequest, id: int, token: str, hash: str) -> HttpRe
         id = source_file.id
         source = source_file.source
         config = get_site_config_from_schema(source_file.config_schema, source_file.config)
-        response = f"{source}().inject({{config:{json.dumps(config)},posthog:window['__$$ph_site_app_{id}']}})"
+
+        response = f"globalConfig = {json.dumps(config)};"
+        response += "function get_global(key) {return globalConfig[key]}"
+
+        extra = ""
+        for key, value in config.items():
+            if isinstance(value, str) and "{" in value:
+                stmt = ast.ReturnStatement(expr=parse_string_template(value))
+                code = create_javascript(
+                    ast.Function(name=f"__get_config_{key}", body=ast.Block(declarations=[stmt]), params=["event"])
+                ).code
+                extra += code + "\n"
+        response += extra
+
+        response += f"{source}().inject({{config:globalConfig,posthog:window['__$$ph_site_app_{id}']}});"
 
         statsd.incr(f"posthog_cloud_raw_endpoint_success", tags={"endpoint": "site_app"})
         return HttpResponse(content=response, content_type="application/javascript")