Set constraints on Readouts.user_id foreign key

Add Measurements table

DESIGN.md

@@ -34,10 +34,10 @@ whenever a change is considered, to avoid regressions.
       custom `BigDecimal` type
 
 ### Database layer vs application layer data model constraints
-* database constraints are the final frontier against data corruption,
+* database constraints are the final guard against data integrity corruption,
-    * they should safeguard against data _consistency_ loss under _all_ data
+    * they should safeguard against data referential integrity loss under _all_
-      (not schema) manipulation scenarios, including application level logic
+      data (not schema) manipulation scenarios, including application level
-      errors and direct data manipulation,
+      logic errors and direct data manipulation (e.g. through `dbconsole`),
 * application constraints can be as restrictive as database constraints or more,
   but not less, as it doesn't serve any use case,
     * proper application level constraints should prevent unhandled database

README.md

@@ -144,6 +144,10 @@ below shows how to grant privileges to all databases which names start with
     mysql> grant all privileges on `fixinme-%`.* to `fixinme-dev`@localhost;
     mysql> flush privileges;
 
+Dumping development data before database reset:
+
+    mysqldump -h <address> -u <user> -p --no-create-info --no-tablespaces --complete-insert <database> > tmp/data.sql
+
 ### Development environment
 
 Starting application server in development environment:

app/controllers/readouts_controller.rb

@@ -6,7 +6,7 @@ class ReadoutsController < ApplicationController
   def new
     @quantities -= @prev_quantities
     # TODO: raise ParameterInvalid if new_quantities.empty?
-    @readouts = current_user.readouts.build(@quantities.map { |q| {quantity: q} })
+    @readouts = @quantities.map { |q| q.readouts.build }
 
     @user_units = current_user.units.ordered
 

app/models/quantity.rb

@@ -6,6 +6,7 @@ class Quantity < ApplicationRecord
   belongs_to :parent, optional: true, class_name: "Quantity"
   has_many :subquantities, ->{ order(:name) }, class_name: "Quantity",
     inverse_of: :parent, dependent: :restrict_with_error
+  has_many :readouts, dependent: :restrict_with_error
 
   validate if: ->{ parent.present? } do
     errors.add(:parent, :user_mismatch) unless user_id == parent.user_id

app/models/readout.rb

@@ -4,4 +4,6 @@ class Readout < ApplicationRecord
   belongs_to :user
   belongs_to :quantity
   belongs_to :unit
+
+  # TODO: validate quantity.user_id == unit.user_id != NULL
 end

db/migrate/20230602185352_create_units.rb

@@ -10,5 +10,6 @@ class CreateUnits < ActiveRecord::Migration[8.1]
       t.timestamps
     end
     add_index :units, [:user_id, :symbol]
+    add_index :units, [:id, :user_id]
   end
 end

db/migrate/20250104194343_create_quantities.rb

@@ -13,5 +13,6 @@ class CreateQuantities < ActiveRecord::Migration[8.1]
       t.string :pathname, null: false, limit: 511
     end
     add_index :quantities, [:user_id, :parent_id, :name]
+    add_index :quantities, [:id, :user_id]
   end
 end

db/migrate/20250121230456_create_readouts.rb

@@ -1,16 +1,63 @@
 class CreateReadouts < ActiveRecord::Migration[8.1]
   def change
-    create_table :readouts do |t|
+    create_table :measurements do |t|
-      t.references :user, null: false, foreign_key: {on_delete: :cascade}
+      t.datetime :taken_at, null: false
-      t.references :quantity, null: false, foreign_key: true
-      # :category + :value + :unit as a separate table? (NumericValue, TextValue)
-      t.integer :category, null: false, default: 0
-      t.float :value, null: false, limit: Float::MANT_DIG
-      t.references :unit, foreign_key: true
       #t.references :collector, foreign_key: true
       #t.references :device, foreign_key: true
+      #t.references :note, foreign_key: true
 
       t.timestamps
     end
+    add_index :measurements, :taken_at
+
+    # Defining Readouts as a super-/subclass polymorphic relations for different
+    # subclass data types (numeric, string, file) is not possible with proper
+    # referential integrity constraints. The required constraints are:
+    # * for every subclass record to have superclass record,
+    # * for every superclass record to have only one type of subclass record,
+    # * for every superclass record to have subclass record (unenforcable).
+    #   * this can be partially remedied by making superlass an abstract class in
+    #     Rails and disallow direct creation of records, but direct data
+    #     manipulation can still break referential integrity.
+    # Defining separate {Numeric,Text,File}_Readouts tables would make the
+    # unique index constraint unenforcable.
+    create_table :readouts do |t|
+      t.references :user, null: false, foreign_key: {on_delete: :cascade}
+      t.references :measurement, foreign_key: {on_delete: :cascade}
+      t.references :quantity, null: false, foreign_key: {on_delete: :cascade}
+      t.integer :category, null: false, default: 0
+      t.float :value, null: false, limit: Float::MANT_DIG
+      t.references :unit, null: false, foreign_key: {on_delete: :cascade}
+      # TODO: consider additional columns to allow wider range of value types
+      # t.text :text
+      # t.datetime :time
+      # t.references :file
+      # Possibly mutually exclusive with :unit or check constraint for:
+      #   :unit is not null <=> :value is not null
+
+      t.timestamps
+    end
+    add_index :readouts, [:measurement_id, :quantity_id, :category]
+    add_foreign_key :readouts, :quantities, column: [:quantity_id, :user_id],
+      primary_key: [:id, :user_id]
+    add_foreign_key :readouts, :units, column: [:unit_id, :user_id],
+      primary_key: [:id, :user_id]
+
+    # TODO: remove below tables after current setup verified
+    #create_table :numeric_values do |t|
+    #  t.references :readout, null: false, foreign_key: {on_delete: :cascade}
+    #  t.float :value, null: false, limit: Float::MANT_DIG
+    #  t.references :unit, null: false, foreign_key: {on_delete: :cascade}
+    #  # + generated, not stored column :value_type
+    #  # + foreign key constraint to readouts: [:readout_id, :value_id, :value_type]
+    #  # or 2 constraints: [:readout_id, :value_id], [:value_id, :value_type]
+    #  # if readouts.value_id needed, otherwise just one constraint:
+    #  # [:readout_id, :value_type]
+    #end
+
+    #create_table :string_values do |t|
+    #  t.references :readout, null: false, foreign_key: {on_delete: :cascade}
+    #  t.string :value, null: false, limit: 32
+    #end
   end
 end

db/schema.rb

@@ -10,7 +10,14 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_01_21_230456) do
+ActiveRecord::Schema[8.1].define(version: 2025_01_21_230456) do
+  create_table "measurements", charset: "utf8mb4", collation: "utf8mb4_0900_as_ci", force: :cascade do |t|
+    t.datetime "taken_at", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["taken_at"], name: "index_measurements_on_taken_at", unique: true
+  end
+
   create_table "quantities", charset: "utf8mb4", collation: "utf8mb4_0900_as_ci", force: :cascade do |t|
     t.bigint "user_id"
     t.string "name", limit: 31, null: false
@@ -20,6 +27,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_01_21_230456) do
     t.datetime "updated_at", null: false
     t.integer "depth", default: 0, null: false
     t.string "pathname", limit: 511, null: false
+    t.index ["id", "user_id"], name: "index_quantities_on_id_and_user_id", unique: true
     t.index ["parent_id"], name: "index_quantities_on_parent_id"
     t.index ["user_id", "parent_id", "name"], name: "index_quantities_on_user_id_and_parent_id_and_name", unique: true
     t.index ["user_id"], name: "index_quantities_on_user_id"
@@ -27,14 +35,18 @@ ActiveRecord::Schema[8.0].define(version: 2025_01_21_230456) do
 
   create_table "readouts", charset: "utf8mb4", collation: "utf8mb4_0900_as_ci", force: :cascade do |t|
     t.bigint "user_id", null: false
+    t.bigint "measurement_id"
     t.bigint "quantity_id", null: false
     t.integer "category", default: 0, null: false
     t.float "value", limit: 53, null: false
-    t.bigint "unit_id"
+    t.bigint "unit_id", null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
-    t.index ["quantity_id", "created_at"], name: "index_readouts_on_quantity_id_and_created_at", unique: true
+    t.index ["measurement_id", "quantity_id", "category"], name: "index_readouts_on_measurement_id_and_quantity_id_and_category", unique: true
+    t.index ["measurement_id"], name: "index_readouts_on_measurement_id"
+    t.index ["quantity_id", "user_id"], name: "fk_rails_9d92eaafc6"
     t.index ["quantity_id"], name: "index_readouts_on_quantity_id"
+    t.index ["unit_id", "user_id"], name: "fk_rails_348b0fb4c5"
     t.index ["unit_id"], name: "index_readouts_on_unit_id"
     t.index ["user_id"], name: "index_readouts_on_user_id"
   end
@@ -48,6 +60,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_01_21_230456) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.index ["base_id"], name: "index_units_on_base_id"
+    t.index ["id", "user_id"], name: "index_units_on_id_and_user_id", unique: true
     t.index ["user_id", "symbol"], name: "index_units_on_user_id_and_symbol", unique: true
     t.index ["user_id"], name: "index_units_on_user_id"
   end
@@ -72,8 +85,11 @@ ActiveRecord::Schema[8.0].define(version: 2025_01_21_230456) do
 
   add_foreign_key "quantities", "quantities", column: "parent_id", on_delete: :cascade
   add_foreign_key "quantities", "users", on_delete: :cascade
-  add_foreign_key "readouts", "quantities"
+  add_foreign_key "readouts", "measurements", on_delete: :cascade
-  add_foreign_key "readouts", "units"
+  add_foreign_key "readouts", "quantities", column: ["quantity_id", "user_id"], primary_key: ["id", "user_id"]
+  add_foreign_key "readouts", "quantities", on_delete: :cascade
+  add_foreign_key "readouts", "units", column: ["unit_id", "user_id"], primary_key: ["id", "user_id"]
+  add_foreign_key "readouts", "units", on_delete: :cascade
   add_foreign_key "readouts", "users", on_delete: :cascade
   add_foreign_key "units", "units", column: "base_id", on_delete: :cascade
   add_foreign_key "units", "users", on_delete: :cascade

db/sqlite3_schema.rb

@@ -10,7 +10,13 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_01_21_230456) do
+ActiveRecord::Schema[8.1].define(version: 2025_01_21_230456) do
+  create_table "measurements", force: :cascade do |t|
+    t.datetime "taken_at", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
   create_table "quantities", force: :cascade do |t|
     t.integer "user_id"
     t.string "name", limit: 31, null: false
@@ -20,6 +26,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_01_21_230456) do
     t.datetime "updated_at", null: false
     t.integer "depth", default: 0, null: false
     t.string "pathname", limit: 511, null: false
+    t.index ["id", "user_id"], name: "index_quantities_on_id_and_user_id", unique: true
     t.index ["parent_id"], name: "index_quantities_on_parent_id"
     t.index ["user_id", "parent_id", "name"], name: "index_quantities_on_user_id_and_parent_id_and_name", unique: true
     t.index ["user_id"], name: "index_quantities_on_user_id"
@@ -27,13 +34,15 @@ ActiveRecord::Schema[8.0].define(version: 2025_01_21_230456) do
 
   create_table "readouts", force: :cascade do |t|
     t.integer "user_id", null: false
+    t.integer "measurement_id"
     t.integer "quantity_id", null: false
     t.integer "category", default: 0, null: false
     t.float "value", limit: 53, null: false
-    t.integer "unit_id"
+    t.integer "unit_id", null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
-    t.index ["quantity_id", "created_at"], name: "index_readouts_on_quantity_id_and_created_at", unique: true
+    t.index ["measurement_id", "quantity_id", "category"], name: "index_readouts_on_measurement_id_and_quantity_id_and_category", unique: true
+    t.index ["measurement_id"], name: "index_readouts_on_measurement_id"
     t.index ["quantity_id"], name: "index_readouts_on_quantity_id"
     t.index ["unit_id"], name: "index_readouts_on_unit_id"
     t.index ["user_id"], name: "index_readouts_on_user_id"
@@ -48,6 +57,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_01_21_230456) do
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.index ["base_id"], name: "index_units_on_base_id"
+    t.index ["id", "user_id"], name: "index_units_on_id_and_user_id", unique: true
     t.index ["user_id", "symbol"], name: "index_units_on_user_id_and_symbol", unique: true
     t.index ["user_id"], name: "index_units_on_user_id"
   end
@@ -72,8 +82,11 @@ ActiveRecord::Schema[8.0].define(version: 2025_01_21_230456) do
 
   add_foreign_key "quantities", "quantities", column: "parent_id", on_delete: :cascade
   add_foreign_key "quantities", "users", on_delete: :cascade
-  add_foreign_key "readouts", "quantities"
+  add_foreign_key "readouts", "measurements", on_delete: :cascade
-  add_foreign_key "readouts", "units"
+  add_foreign_key "readouts", "quantities", column: ["quantity_id", "user_id"], primary_key: ["id", "user_id"]
+  add_foreign_key "readouts", "quantities", on_delete: :cascade
+  add_foreign_key "readouts", "units", column: ["unit_id", "user_id"], primary_key: ["id", "user_id"]
+  add_foreign_key "readouts", "units", on_delete: :cascade
   add_foreign_key "readouts", "users", on_delete: :cascade
   add_foreign_key "units", "units", column: "base_id", on_delete: :cascade
   add_foreign_key "units", "users", on_delete: :cascade