Add latest nutrient measurement/target hash retrieval function.

1 files changed, 15 insertions, 0 deletions

diff --git a/models/nutrient-target.rkt b/models/nutrient-target.rkt
index b9ca2d1..261fce0 100644
--- a/models/nutrient-target.rkt
+++ b/models/nutrient-target.rkt
@@ -142,6 +142,21 @@
                              #:desc
                              #:limit 1)))
 
+(define (get-latest-nutrient-target-hash)
+  (for/hash ([(n-id n-name n-formula residual-rows)
+              (in-query (current-conn)
+                                    (select n.id
+                                            n.canonical_name
+                                            n.formula
+                                            nt.effective_on
+                                            nv.value_ppm
+                                            #:from (TableExpr:AST ,joined)
+                                            #:order-by nt.effective_on
+                                            #:desc)
+                                    #:group '(#(0 1 2)))])
+    ;; residual-rows is a non-empty list of vectors: #(effective_on value_ppm)
+    (match-define (vector _effective-on value-ppm) (first residual-rows))
+    (values (nutrient n-id n-name n-formula) value-ppm)))
 
 ;; UPDATE