Question: Web Apps, forms and UI

using an MVC architecture in a ring based web app. In a controller function for an edit form, I want to be able to assoc-in multiple bits of data to the request map which include the data for the form itself, data to populate at least one dropdown, and when I get there, validation messaging such as "Name is required".Since the request map isn't mutable, my naive view of a potential solution would be to use a chain of functions to modify the request. Here's what I have now to populate the form with data, depending on if it is a new record or an edit:

(defn edit-nutrient [req]
(view/nutrient-form (nutrient-form-data req)))(defn nutrient-form-data [req]
(if (nil? (get-in req [:path-params :id]))
(assoc-in req [:params :q] [{:eid -1 :name "" :grams-in-stock 0 :purchase-url "" :note ""}])
(assoc-in req [:params :q] (m/find-nutrient (Long/parseLong (get-in req [:path-params :id]))))))

edit-nutrient is the actual controller function and nutrient-form-data a helper function.Now I want to add (assoc-in req [:params :qc] (m/find-all-categories)) to the processing here and feel that this is not a clean approach to passing data into a view, particularly if it requires multiple chunks of data.

Best practice suggestions

Start with the edit-nutrient and nutrient-form-data functions shown in the issue, then inspect nearby controller and view conventions in the repository. Determine whether the project has an established pattern for supplying form, dropdown, and validation data, and document a clear recommendation if one is needed.