[Racket] Ferti hydroponic nutrient solver, redux.
Add get-latest-nutrient-measurement helper.
models/nutrient-measurement.rkt
@@ -13,6 +13,7 @@
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[get-nutrient-measurement-values (-> nutrient-measurement-or-id/c nutrient-value-hash/c)]
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[get-nutrient-measurement-value
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(-> nutrient-measurement-or-id/c nutrient? maybe-nutrient-value?)]
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Added:
[get-latest-nutrient-measurement (-> (or/c nutrient-measurement? #f))]
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[get-latest-nutrient-measurement-value (-> nutrient? maybe-nutrient-value?)]
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[get-latest-nutrient-measurement-values (-> nutrient-value-hash/c)]
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[delete-nutrient-measurement! (-> nutrient-measurement-or-id/c void?)]))
@@ -146,6 +147,12 @@
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#:from (TableExpr:AST ,joined)
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#:where (and (= nm.id ,(->nm-id nm-or-id))
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(= nv.nutrient_id ,(nutrient-id nutrient))))))
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(define (get-latest-nutrient-measurement)
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(define measurements (get-nutrient-measurements))
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(if (null? measurements)
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#f
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(first measurements)))
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(define (get-latest-nutrient-measurement-value nutrient)
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(query-maybe-value (current-conn)