From 434b521ddb70287b55d1dc8f5e24f18aeaa01fdc Mon Sep 17 00:00:00 2001
From: Marius Peter <dev@marius-peter.com>
Date: Thu, 20 Nov 2025 11:35:24 +0100
Subject: Add latest nutrient measurement/target hash retrieval function.

---
 models/nutrient-measurement.rkt | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'models/nutrient-measurement.rkt')

diff --git a/models/nutrient-measurement.rkt b/models/nutrient-measurement.rkt
index dbcb53c..199208f 100644
--- a/models/nutrient-measurement.rkt
+++ b/models/nutrient-measurement.rkt
@@ -148,6 +148,21 @@
                              #:desc
                              #:limit 1)))
 
+(define (get-latest-nutrient-measurement-hash)
+  (for/hash ([(n-id n-name n-formula residual-rows)
+              (in-query (current-conn)
+                        (select n.id
+                                n.canonical_name
+                                n.formula
+                                nm.measured_on
+                                nv.value_ppm
+                                #:from (TableExpr:AST ,joined)
+                                #:order-by nm.measured_on
+                                #:desc)
+                        #:group '(#(0 1 2)))])
+    ;; residual-rows is a non-empty list of vectors: #(measured_on value_ppm)
+    (match-define (vector _measured-on value-ppm) (first residual-rows))
+    (values (nutrient n-id n-name n-formula) value-ppm)))
 
 ;; UPDATE
 
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