generating query filter dynamically

[roti]

Hi,

I'm trying to generate the filter expression dynamically. It does not seem possible with the current implementation of query. Take following function

(defn filterexpand [params]
(map #(list '= (key %) (val %)) params))

Using it like this is not possible:
(defn search-orders [params]
(let [o (ds/query :kind Order (filterexpand params))]
(map-xml-list o)))

I also tried with a macro version of filterexpand:
(defmacro filterexpand [body]
(let [p (eval body)]
(map #(list '= (key %) (val%)) p)))

Can such usage of query be made possible?

Razvan

[gcv]

I can probably support this use case, although it will not use the :filter keyword to query. It would need to use a different keyword, perhaps :eval-filter, because otherwise it'll be impossible to distinguish between the following two uses:

(query :kind Order :filter (= :type "book"))
(query :kind Order :filter (filterexpand params))

I understand the appeal, though, and I'll keep this ticket open as a feature request for a future version. In the meanwhile, if you really need this, you can hack something together: you would need to construct the entire (query ...) expression as a list and eval it.

[roti]

I have tried but ended up in a "Can't eval locals" error. It's very likely you stumble upon the same error.

Anyway, why not make it simple: if no operator recognized after :filter (no =, <, >, etc.), then just assume that there's an expression there that needs evaluation. In other words, just make :eval-filter an else-branch of :filter.