fix(ai-templater): improved error handling

kong/plugins/ai-prompt-template/handler.lua

@@ -49,23 +49,19 @@ local function is_reference(reference)
 end
 
 local function find_template(reference_string, templates)
-  if is_reference(reference_string) then
-    local parts, err = parse_url(sub(reference_string, 2, -2))
-    if not parts then
-      return nil, fmt("template reference is not in format '{template://template_name}' (%s) [%s]", err, reference_string)
-    end
+  local parts, err = parse_url(sub(reference_string, 2, -2))
+  if not parts then
+    return nil, fmt("template reference is not in format '{template://template_name}' (%s) [%s]", err, reference_string)
+  end
 
-    -- iterate templates to find it
-    for i, v in ipairs(templates) do
-      if v.name == parts.host then
-        return v, nil
-      end
+  -- iterate templates to find it
+  for i, v in ipairs(templates) do
+    if v.name == parts.host then
+      return v, nil
     end
-
-    return nil, "could not find template name [" .. parts.host .. "]"
   end
 
-  return nil, "'messages' template reference should be a single string, in format '{template://template_name}'"
+  return nil, fmt("could not find template name [%s]", parts.host)
 end
 
 function _M:access(conf)
@@ -100,17 +96,22 @@ function _M:access(conf)
     return bad_request("only 'llm/v1/chat' and 'llm/v1/completions' formats are supported for templating")
   end
 
-  local requested_template, err = find_template(reference, conf.templates)
-  if err and (not conf.allow_untemplated_requests) then bad_request(err) end
+  if is_reference(reference) then
+    local requested_template, err = find_template(reference, conf.templates)
+    if not requested_template then
+      return bad_request(err)
+    end
 
-  if not err then
     -- try to render the replacement request
     local rendered_template, err = templater:render(requested_template, request.properties or {})
     if err then
       return bad_request(err)
     end
 
     kong.service.request.set_raw_body(rendered_template)
+
+  elseif not (conf.allow_untemplated_requests) then
+    return bad_request("this LLM route only supports templated requests")
   end
 end
 

spec/03-plugins/43-ai-prompt-template/02-integration_spec.lua

@@ -99,6 +99,14 @@ for _, strategy in helpers.all_strategies() do if strategy ~= "cassandra" then
                 }
               ]],
             },
+            [2] = {
+              name = "developer-completions",
+              template = [[
+                {
+                  "prompt": "You are a {{language}} programming expert. Make me a {{program}} program."
+                }
+              ]],
+            },
           },
         },
       }
@@ -211,7 +219,7 @@ for _, strategy in helpers.all_strategies() do if strategy ~= "cassandra" then
         local body = assert.res_status(400, r)
         local json = cjson.decode(body)
 
-        assert.same(json, { error = { message = "'messages' template reference should be a single string, in format '{template://template_name}'" }})
+        assert.same(json, { error = { message = "this LLM route only supports templated requests" }})
       end)
 
       it("doesn't block when 'allow_untemplated_requests' is ON", function()
@@ -232,7 +240,7 @@ for _, strategy in helpers.all_strategies() do if strategy ~= "cassandra" then
           ]],
           method = "POST",
         })
-        
+
         local body = assert.res_status(200, r)
         local json = cjson.decode(body)
 
@@ -256,13 +264,33 @@ for _, strategy in helpers.all_strategies() do if strategy ~= "cassandra" then
           ]],
           method = "POST",
         })
-        
+
         local body = assert.res_status(400, r)
         local json = cjson.decode(body)
 
         assert.same(json, { error = { message = "could not find template name [developer-doesnt-exist]" }} )
       end)
 
+      it("still errors with a not found template when 'allow_untemplated_requests' is ON", function()
+        local r = client:get("/request", {
+          headers = {
+            host = "test1.com",
+            ["Content-Type"] = "application/json",
+          },
+          body = [[
+            {
+              "messages": "{template://not_found}"
+            }  
+          ]],
+          method = "POST",
+        })
+
+        local body = assert.res_status(400, r)
+        local json = cjson.decode(body)
+
+        assert.same(json, { error = { message = "could not find template name [not_found]" }} )
+      end)
+
       it("errors with missing template parameter", function()
         local r = client:get("/request", {
           headers = {
@@ -279,7 +307,7 @@ for _, strategy in helpers.all_strategies() do if strategy ~= "cassandra" then
           ]],
           method = "POST",
         })
-        
+
         local body = assert.res_status(400, r)
         local json = cjson.decode(body)