Fix quantity ordered scope for SQLite: use pathname column instead of recursive CTE

SQLite's Arel visitor wraps CTE branches in extra parentheses, making
the UNION ALL inside recursive CTEs invalid. Also SQLite lacks LPAD()
and CAST(... AS BINARY). Fix by using the existing pathname column for
ordering on SQLite, which already encodes the hierarchical path.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/assets/images/pictograms/alert-outline.svg

@@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" id="icon" viewBox="0 0 24 24"><path fill="#ffffff" d="M12,2L1,21H23M12,6L19.53,19H4.47M11,10V14H13V10M11,16V18H13V16" /></svg>
+<svg xmlns="http://www.w3.org/2000/svg" id="icon" viewBox="0 0 24 24"><path d="M12,2L1,21H23M12,6L19.53,19H4.47M11,10V14H13V10M11,16V18H13V16" /></svg>

app/assets/images/pictograms/check-circle-outline.svg

@@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" id="icon" viewBox="0 0 24 24"><path fill="#ffffff" d="M12 2C6.5 2 2 6.5 2 12S6.5 22 12 22 22 17.5 22 12 17.5 2 12 2M12 20C7.59 20 4 16.41 4 12S7.59 4 12 4 20 7.59 20 12 16.41 20 12 20M16.59 7.58L10 14.17L7.41 11.59L6 13L10 17L18 9L16.59 7.58Z" /></svg>
+<svg xmlns="http://www.w3.org/2000/svg" id="icon" viewBox="0 0 24 24"><path d="M12 2C6.5 2 2 6.5 2 12S6.5 22 12 22 22 17.5 22 12 17.5 2 12 2M12 20C7.59 20 4 16.41 4 12S7.59 4 12 4 20 7.59 20 12 16.41 20 12 20M16.59 7.58L10 14.17L7.41 11.59L6 13L10 17L18 9L16.59 7.58Z" /></svg>

app/assets/stylesheets/application.css

@@ -18,10 +18,14 @@
 /* Strive for simplicity:
  * * style elements/tags only - if possible,
  * * replace element/tag name with class name - if element has to be styled
- * differently depending on context (e.g. form)
+ * differently depending on context (e.g. <form>; <a> as link/button),
+ * * styles with multiple selectors should have all selectors with same
+ * specificity, to allow proper rule specificity vs order management.
  *
- * NOTE: Style in a modular way, similar to how CSS @scope would be used,
+ * NOTE: style in a modular way, similar to how CSS @scope would be used,
- * to make transition easier once @scope is widely available */
+ * to make transition easier once @scope is widely available. */
+/* TODO: review styles with multiple selectors and try to convert them to the same
+ * specificity. */
 :root {
   --color-focus-gray: #f3f3f3;
   --color-border-gray: #dddddd;
@@ -53,12 +57,26 @@
 :focus-visible {
   outline: none;
 }
+/* NOTE: move to higher priority layer instead of using !important? */
+[disabled] {
+  border-color: var(--color-border-gray) !important;
+  color: var(--color-border-gray) !important;
+  /* NOTE: cannot set cursor with `pointer-events: none`; can be fixed by setting
+   * `cursor` on wrapping element.
+  cursor: not-allowed; */
+  fill: var(--color-border-gray) !important;
+  pointer-events: none !important;
+}
+/* [hidden] submit elements cannot have `display` set as it makes them visible. */
+[hidden] {
+  display: none !important;
+}
 
 
 /* Color coding of input controls' background:
- *  blue - target for interaction with pointer
+ *  blue - target for interaction with pointer,
- *  gray - target for interaction with keyboard
+ *  gray - target for interaction with keyboard,
- *  red - destructive, non-undoable action
+ *  red - destructive, non-undoable action.
  */
 button,
 details,
@@ -73,50 +91,17 @@ input,
 select {
   text-align: inherit;
 }
-a,
-button,
-input[type=submit] {
-  cursor: pointer;
-  text-decoration: none;
-  white-space: nowrap;
-}
-/* [hidden] submit controls cannot have `display` set as it makes them visible */
-.button,
-button:not([hidden]),
-input[type=submit]:not([hidden]),
-.tab {
-  align-items: center;
-  color: var(--color-gray);
-  display: flex;
-  fill: var(--color-gray);
-  font-weight: bold;
-}
-.button,
-button,
-input[type=submit] {
-  font-size: 0.8rem;
-  padding: 0.6em 0.5em;
-  width: fit-content;
-}
-input:not([type=submit]):not([type=checkbox]),
-select,
-summary,
-textarea {
-  padding: 0.2em 0.4em;
-}
-.button,
-button,
 input,
 select,
 summary,
 textarea {
-  border: solid 1px var(--color-gray);
+  border: 1px solid var(--color-gray);
   border-radius: 0.25em;
+  padding: 0.2em 0.4em;
 }
-input[type=checkbox],
 svg,
 textarea {
-  margin: 0
+  margin: 0;
 }
 input[type=checkbox] {
   accent-color: var(--color-blue);
@@ -124,13 +109,16 @@ input[type=checkbox] {
   -webkit-appearance: none;
   display: flex;
   height: 1.1em;
+  margin: 0;
+  padding: 0;
   width: 1.1em;
 }
 input[type=checkbox]:checked {
   appearance: checkbox;
   -webkit-appearance: checkbox;
 }
-/* Hide spin buttons in input number fields */
+/* Hide spin buttons of <input type=number>. */
+/* TODO: add spin buttons inside <input type=number>: before (-) and after (+) input. */
 input[type=number] {
   appearance: textfield;
   -moz-appearance: textfield;
@@ -142,52 +130,21 @@ input::-webkit-outer-spin-button {
   -webkit-appearance: none;
   margin: 0;
 }
-.button > svg,
-.tab > svg,
-button > svg {
-  height: 1.4em;
-  width: 1.4em;
-}
-.button > svg:not(:last-child),
-.tab > svg:not(:last-child),
-button > svg:not(:last-child) {
-  margin-right: 0.2em;
-}
-/* TODO: move normal non-button links (<a>:hover/:focus) styling here (i.e.
- * page-wide, top-level) and remove from table.items - as the style should be
- * same everywhere */
-.button:focus-visible,
-button:focus-visible,
-input[type=submit]:focus-visible {
-  background-color: var(--color-focus-gray);
-}
 input:focus-visible,
 select:focus-visible,
 select:focus-within,
-/* TODO: how to achieve summary:focus-within for ::details-content? */
+/* TODO: how to achieve `summary:focus-within` for `::details-content`? */
 summary:focus-visible,
 textarea:focus-visible {
   accent-color: var(--color-dark-blue);
   background-color: var(--color-focus-gray);
 }
-.button:hover,
-button:hover,
-input[type=submit]:hover {
-  background-color: var(--color-blue);
-  border-color: var(--color-blue);
-  color: white;
-  fill: white;
-}
-.dangerous:hover {
-  background-color: var(--color-red);
-  border-color: var(--color-red);
-}
 input:hover,
 select:hover,
 summary:hover,
 textarea:hover {
   border-color: var(--color-blue);
-  outline: solid 1px var(--color-blue);
+  outline: 1px solid var(--color-blue);
 }
 select:hover,
 summary:hover {
@@ -197,8 +154,68 @@ input:invalid,
 select:invalid,
 textarea:invalid {
   border-color: var(--color-red);
-  outline: solid 1px var(--color-red);
+  outline-color: var(--color-red);
 }
+
+/* `.button`: button-styled <a>, <button>, <input type=submit>.
+ * `.link`: any other <a>.
+ * `.tab`: tab-styled <a>.
+ */
+.button,
+.link,
+.tab {
+  cursor: pointer;
+  text-decoration: none;
+  white-space: nowrap;
+}
+.button,
+.tab {
+  align-items: center;
+  color: var(--color-gray);
+  display: flex;
+  fill: var(--color-gray);
+  font-weight: bold;
+}
+.button {
+  border: 1px solid var(--color-gray);
+  border-radius: 0.25em;
+  font-size: 0.8rem;
+  padding: 0.6em 0.5em;
+  width: fit-content;
+}
+[name=cancel],
+.auxiliary {
+  border-color: var(--color-border-gray);
+  color: var(--color-nav-gray);
+  fill: var(--color-nav-gray);
+}
+.button > svg,
+.tab > svg {
+  height: 1.4em;
+  width: 1.4em;
+}
+.button > svg:not(:last-child),
+.tab > svg:not(:last-child) {
+  margin-right: 0.2em;
+}
+.button:focus-visible,
+.tab:focus-visible,
+.tab:hover {
+  background-color: var(--color-focus-gray);
+}
+.button:hover {
+  background-color: var(--color-blue);
+  border-color: var(--color-blue);
+  color: white;
+  fill: white;
+}
+.dangerous:hover {
+  background-color: var(--color-red);
+  border-color: var(--color-red);
+}
+/* TODO: move normal, non-button links (<a>:hover/:focus) styling here (i.e.
+ * page-wide, top-level) and remove from `table.items` - as the style should be
+ * same everywhere. */
 input[type=text]:read-only,
 textarea:read-only {
   border: none;
@@ -206,8 +223,8 @@ textarea:read-only {
 }
 
 
-/* NOTE: collapse gaps around empty rows (`topside`) once possible
+/* NOTE: collapse gaps around empty rows (`topside`) once possible with
- * with grid-collapse property and remove alternative grid-template
+ * `grid-collapse` property and remove alternative `grid-template-areas`.
  * https://github.com/w3c/csswg-drafts/issues/5813 */
 body {
   display: grid;
@@ -240,18 +257,14 @@ header {
   margin-inline-start: 4%;
 }
 .navigation > .tab {
-  border-bottom: solid 2px var(--color-nav-gray);
+  border-bottom: 2px solid var(--color-nav-gray);
   flex: 1;
   font-size: 1rem;
   justify-content: center;
   padding-block: 0.4em;
 }
-.navigation > .tab:hover,
-.navigation > .tab:focus-visible {
-  background-color: var(--color-focus-gray);
-}
 .navigation > .tab.active {
-  border-bottom: solid 4px var(--color-blue);
+  border-bottom: 4px solid var(--color-blue);
   color: var(--color-blue);
   fill: var(--color-blue);
 }
@@ -283,7 +296,7 @@ header {
 
 #flashes {
   display: grid;
-  gap: 0.2em;
+  row-gap: 0.4em;
   grid-template-columns: 1fr auto auto auto 1fr;
   left: 0;
   pointer-events: none;
@@ -299,48 +312,42 @@ header {
   display: grid;
   grid-column: 2/5;
   grid-template-columns: subgrid;
+  line-height: 2.2em;
   pointer-events: auto;
 }
-.flash.alert:before {
+.flash:before {
-  content: url('pictograms/alert-outline.svg');
+  filter: invert();
   height: 1.4em;
   margin: 0 0.5em;
   width: 1.4em;
 }
+.flash.alert:before {
+  content: url('pictograms/alert-outline.svg');
+}
 .flash.alert {
   border-color: var(--color-red);
   background-color: var(--color-red);
 }
 .flash.notice:before {
   content: url('pictograms/check-circle-outline.svg');
-  height: 1.4em;
-  margin: 0 0.5em;
-  width: 1.4em;
 }
 .flash.notice {
   border-color: var(--color-blue);
   background-color: var(--color-blue);
 }
-.flash > div {
+.flash svg {
-  grid-column: 2;
-}
-/* NOTE: currently flash button inherits some unnecessary styles from generic
- * button. */
-.flash > button {
-  border: none;
-  color: inherit;
   cursor: pointer;
-  font-size: 1.4em;
+  fill: white;
-  font-weight: bold;
+  height: 2.2em;
-  grid-column: 3;
   opacity: 0.6;
-  padding: 0.2em 0.4em;
+  padding: 0.4em 0.5em;
+  width: 2.4em;
 }
-.flash > button:hover {
+.flash svg:hover {
   opacity: 1;
 }
 
-/* TODO: Hover over invalid should work like in measurements (thin vs thick border) */
+
 .labeled-form {
   align-items: center;
   display: grid;
@@ -357,7 +364,7 @@ header {
 .labeled-form label.required {
   font-weight: bold;
 }
-/* Don't style `label.error + input` if case already covered by input:invalid */
+/* Don't style `label.error + input` if case already covered by `input:invalid`. */
 .labeled-form label.error {
   color: var(--color-red);
 }
@@ -371,15 +378,23 @@ header {
 }
 .labeled-form input[type=submit] {
   font-size: 1rem;
-  margin: 1.5em auto 0 auto;
+  margin: 1em auto 0 auto;
   padding: 0.75em;
 }
+.labeled-form .auxiliary {
+  grid-column: 3;
+  /* If more buttons are needed, `grid-row` can be replaced with
+   * `reading-flow: grid-columns` to ensure proper [tabindex] order. */
+  grid-row: 1;
+  height: 100%;
+  padding-block: 0;
+}
 
 
-/* TODO: remove .items class (?) and make 'form table' work properly */
+/* TODO: remove `.items` class (?) and make `form table` work properly. */
 table.items {
   border-spacing: 0;
-  border: solid 1px var(--color-border-gray);
+  border: 1px solid var(--color-border-gray);
   border-radius: 0.25em;
   font-size: 0.85rem;
   text-align: left;
@@ -402,7 +417,7 @@ table.items th,
 table.items td {
   padding-inline: 1em 0;
 }
-/* For <a> to fill <td> completely, we use an ::after pseudoelement. */
+/* For <a> to fill <td> completely, we use an `::after` pseudoelement. */
 table.items td.link {
   padding: 0;
   position: relative;
@@ -432,7 +447,7 @@ table.items td:last-child {
   padding-inline-end: 0.1em;
 }
 table.items td {
-  border-top: solid 1px var(--color-border-gray);
+  border-top: 1px solid var(--color-border-gray);
   height: 2.4em;
   padding-block: 0.1em;
 }
@@ -451,7 +466,7 @@ table.items tr.dropzone::after {
   content: '';
   inset: 1px 0 0 0;
   position: absolute;
-  outline: dashed 2px var(--color-blue);
+  outline: 2px dashed var(--color-blue);
   outline-offset: -1px;
   z-index: var(--z-index-table-row-outline);
 }
@@ -462,8 +477,8 @@ table.items tr.form td {
   vertical-align: top;
 }
 
-/* TODO: replace :hover:focus-visible combos with proper LOVE stye order */
+/* TODO: replace `:hover:focus-visible` combos with proper LOVE style order. */
-/* TODO: Update table styling: simplify selectors, deduplicate, remove non-font rem. */
+/* TODO: update table styling: simplify selectors, deduplicate, remove non-font rem. */
 table.items td.link a:hover,
 table.items td.link a:focus-visible,
 table.items td.link a:hover:focus-visible {
@@ -501,9 +516,7 @@ table.items td.svg {
 table.items td.number {
   text-align: right;
 }
-table.items .button,
+table.items .button {
-table.items button,
-table.items input[type=submit] {
   font-weight: normal;
   height: 100%;
   padding: 0.4em;
@@ -513,30 +526,26 @@ table.items select,
 table.items textarea {
   padding-block: 0.375em;
 }
-/* TODO: find a way (layers?) to style inputs differently while making sure
+
- * hover works properly without using :not(:hover) selectors here. */
+table input,
-table.items .button:not(:hover),
+table select,
-table.items button:not(:hover),
+table summary,
-table.items input:not(:hover),
+table textarea {
-table.items select:not(:hover),
-table.items textarea:not(:hover) {
   border-color: var(--color-border-gray);
 }
-table.items .button:not(:hover),
+table select {
-table.items button:not(:hover),
-table.items input[type=submit]:not(:hover),
-table.items select:not(:hover) {
   color: var(--color-table-gray);
 }
-table.items select:focus-within,
+table select:hover,
-table.items select:focus-visible {
+table select:focus-within,
+table select:focus-visible {
   color: black;
 }
-form a[name=cancel] {
+table .button {
   border-color: var(--color-border-gray);
-  color: var(--color-nav-gray);
+  color: var(--color-table-gray);
-  fill: var(--color-nav-gray);
 }
+
 form table.items {
   border: none;
 }
@@ -548,6 +557,9 @@ form table.items td {
 form table.items td:first-child {
   color: inherit;
 }
+form table select {
+  color: black;
+}
 
 
 .centered {
@@ -580,17 +592,6 @@ form table.items td:first-child {
   gap: 0.8em;
   flex-direction: column;
 }
-[disabled] {
-/* label:has(input[disabled]) {
- * TODO: disabled checkbox blue square focus removal; disabled label styling;
- * focused label styling (currently only checkbox has focus)
- * */
-  border-color: var(--color-border-gray) !important;
-  color: var(--color-border-gray) !important;
-  cursor: not-allowed;
-  fill: var(--color-border-gray) !important;
-  pointer-events: none;
-}
 
 
 details {
@@ -618,7 +619,7 @@ summary:has(.button) {
   padding-inline-end: 0;
 }
 summary .button {
-  border: solid 1px var(--color-border-gray);
+  border: 1px solid var(--color-border-gray);
   border-radius: inherit;
   border-top-left-radius: 0;
   border-bottom-left-radius: 0;
@@ -634,10 +635,10 @@ details[open] summary::before {
 summary::marker {
   padding-left: 0.25em;
 }
-/* NOTE: use details[open]::details-content once widely available */
+/* NOTE: use `details[open]::details-content` once widely available. */
 details[open] ul {
   background: white;
-  border: solid 1px var(--color-border-gray);
+  border: 1px solid var(--color-border-gray);
   border-radius: 0.25em;
   box-shadow: 1px 1px 3px var(--color-border-gray);
   margin: -1px 0 0 0;
@@ -659,3 +660,10 @@ li input[type=checkbox] {
 li::marker {
   content: '';
 }
+/*
+ * TODO:
+ * * disable <label> containing disabled checkbox: `label:has(input[disabled])`,
+ * * disabled label styling,
+ * * focused label styling (currently only checkbox has focus),
+ * * disabled checkbox blue square focus removal.
+ * */

app/controllers/measurements_controller.rb

@@ -1,7 +1,13 @@
 class MeasurementsController < ApplicationController
+  before_action except: :index do
+    raise AccessForbidden unless current_user.at_least(:active)
+  end
+
   def index
-    @measurements = []
+    readouts = current_user.readouts.includes(:quantity, :unit).order(created_at: :desc)
-    #@measurements = current_user.units.ordered.includes(:base, :subunits)
+    @measurements = readouts.group_by(&:created_at).map do |created_at, grouped|
+      Measurement.new(created_at: created_at, readouts: grouped)
+    end
   end
 
   def new
@@ -9,8 +15,33 @@ class MeasurementsController < ApplicationController
   end
 
   def create
+    timestamp = Time.current
+    @readouts = readout_params.map do |rp|
+      r = current_user.readouts.new(rp)
+      r.created_at = timestamp
+      r
+    end
+
+    if @readouts.all?(&:valid?)
+      Readout.transaction { @readouts.each(&:save!) }
+      @measurement = Measurement.new(readouts: @readouts, created_at: timestamp)
+      flash.now[:notice] = t('.success')
+    else
+      render :new, status: :unprocessable_entity
+    end
   end
 
   def destroy
+    @measurement = Measurement.new(id: params[:id].to_i,
+                                   created_at: Time.at(params[:id].to_i))
+    current_user.readouts.where(created_at: @measurement.created_at).delete_all
+    @measurements_empty = current_user.readouts.empty?
+    flash.now[:notice] = t('.success')
+  end
+
+  private
+
+  def readout_params
+    params.require(:readouts).map { |r| r.permit(:quantity_id, :value, :unit_id) }
   end
 end

app/controllers/registrations_controller.rb

@@ -2,7 +2,11 @@ class RegistrationsController < Devise::RegistrationsController
   before_action :authenticate_user!, only: [:edit, :update, :destroy]
 
   def destroy
-    # TODO: Disallow/disable deletion for last admin account; update :edit view
+    if current_user.sole_admin?
+      redirect_back fallback_location: edit_user_registration_path,
+        alert: t(".sole_admin")
+      return
+    end
     super
   end
 

app/helpers/application_helper.rb

@@ -12,6 +12,12 @@ module ApplicationHelper
       labeled_field_for(method, options) { super }
     end
 
+    def submit(value = nil, options = {})
+      value, options = nil, value if value.is_a?(Hash)
+      options[:class] = @template.class_names('button', options[:class])
+      super
+    end
+
     private
 
     def labeled_field_for(method, options)
@@ -72,13 +78,8 @@ module ApplicationHelper
   end
 
   def labeled_form_for(record, options = {}, &block)
-    extra_options = {builder: LabeledFormBuilder,
+    extra_options = {builder: LabeledFormBuilder, html: {class: 'labeled-form'}}
-                     data: {turbo: false},
+    form_for(record, **merge_attributes(options, extra_options), &block)
-                     html: {class: 'labeled-form'}}
-    options = options.deep_merge(extra_options) do |key, left, right|
-      key == :class ? class_names(left, right) : right
-    end
-    form_for(record, **options, &block)
   end
 
   class TabularFormBuilder < ActionView::Helpers::FormBuilder
@@ -113,8 +114,12 @@ module ApplicationHelper
     end
 
     def button(value = nil, options = {}, &block)
-      # button does not use #objectify_options
+      # #button does not use #objectify_options/@default_options
-      options.merge!(@options.slice(:form))
+      value, options = nil, value if value.is_a?(Hash)
+      options = options.merge(
+        @default_options.slice(:form),
+        class: @template.class_names('button', options[:class])
+      )
       super
     end
 
@@ -135,20 +140,21 @@ module ApplicationHelper
     # [autofocus].  Otherwise IDs are not unique when multiple forms are open
     # and the first input gets focus.
     record_object, options = nil, record_object if record_object.is_a?(Hash)
-    options.merge!(builder: TabularFormBuilder, skip_default_ids: true)
+    extra_options = {builder: TabularFormBuilder, skip_default_ids: true}
+    options = merge_attributes(options, extra_options)
     # TODO: set error message with setCustomValidity instead of rendering to flash?
     render_errors(record_object || record_name)
     fields_for(record_name, record_object, **options, &block)
   end
 
   def tabular_form_with(**options, &block)
-    options = options.deep_merge(builder: TabularFormBuilder,
+    extra_options = {builder: TabularFormBuilder, html: {autocomplete: 'off'}}
-                                 html: {autocomplete: 'off'})
+    form_with(**merge_attributes(options, extra_options), &block)
-    form_with(**options, &block)
   end
 
   def svg_tag(source, label = nil, options = {})
-    svg_tag = tag.svg(options) do
+    label, options = nil, label if label.is_a? Hash
+    svg_tag = tag.svg(**options) do
       tag.use(href: "#{image_path(source + ".svg")}#icon")
     end
     label.blank? ? svg_tag : svg_tag + tag.span(label)
@@ -159,6 +165,7 @@ module ApplicationHelper
       ['measurements', 'scale-bathroom', :restricted],
       ['quantities', 'axis-arrow', :restricted, 'right'],
       ['units', 'weight-gram', :restricted],
+      # TODO: display users tab only if >1 user present; sole_user?/sole_admin?
       ['users', 'account-multiple-outline', :admin],
     ]
 
@@ -206,6 +213,7 @@ module ApplicationHelper
 
   def render_errors(records)
     # Conversion of flash to Array only required because of Devise
+    # TODO: override Devise message setting to Array()?
     flash[:alert] = Array(flash[:alert])
     Array(records).each { |record| flash[:alert] += record.errors.full_messages }
   end
@@ -215,8 +223,8 @@ module ApplicationHelper
       # Conversion of flash to Array only required because of Devise
       Array(messages).map do |message|
         tag.div class: "flash #{entry}" do
-          tag.div(sanitize(message)) + tag.button(sanitize("&times;"), tabindex: -1,
+          tag.span(sanitize(message)) +
-                                                  onclick: "this.parentElement.remove();")
+            svg_tag('pictograms/close-outline', {onclick: "this.parentElement.remove()"})
         end
       end
     end.join.html_safe
@@ -252,4 +260,11 @@ module ApplicationHelper
 
     [name, html_options]
   end
+
+  # Like Hash#deep_merge, but aware of HTML attributes.
+  def merge_attributes(left, right)
+    left.deep_merge(right) do |key, lvalue, rvalue|
+      key == :class ? class_names(lvalue, rvalue) : rvalue
+    end
+  end
 end

app/models/measurement.rb

@@ -1,3 +1,17 @@
 class Measurement
   include ActiveModel::Model
+
+  attr_accessor :readouts, :created_at
+
+  def id
+    created_at.to_i
+  end
+
+  def to_param
+    id.to_s
+  end
+
+  def persisted?
+    true
+  end
 end

app/models/quantity.rb

@@ -61,18 +61,26 @@ class Quantity < ApplicationRecord
 
   # Return: ordered [sub]hierarchy
   scope :ordered, ->(root: nil, include_root: true) {
-    numbered = Arel::Table.new('numbered')
+    if connection.adapter_name =~ /mysql/i
-
+      numbered = Arel::Table.new('numbered')
-    self.model.with(numbered: numbered(:parent_id, :name)).with_recursive(arel_table.name => [
+      self.model.with(numbered: numbered(:parent_id, :name)).with_recursive(arel_table.name => [
-      numbered.project(
+        numbered.project(
-        numbered[Arel.star],
+          numbered[Arel.star],
-        numbered.cast(numbered[:child_number], 'BINARY').as('path')
+          numbered.cast(numbered[:child_number], 'BINARY').as('path')
-      ).where(numbered[root && include_root ? :id : :parent_id].eq(root)),
+        ).where(numbered[root && include_root ? :id : :parent_id].eq(root)),
-      numbered.project(
+        numbered.project(
-        numbered[Arel.star],
+          numbered[Arel.star],
-        arel_table[:path].concat(numbered[:child_number])
+          arel_table[:path].concat(numbered[:child_number])
-      ).join(arel_table).on(numbered[:parent_id].eq(arel_table[:id]))
+        ).join(arel_table).on(numbered[:parent_id].eq(arel_table[:id]))
-    ]).order(arel_table[:path])
+      ]).order(arel_table[:path])
+    elsif root.nil?
+      # SQLite: pathname column already stores the full hierarchical path
+      order(:pathname)
+    else
+      root_pathname = unscoped.where(id: root).pick(:pathname)
+      scope = order(:pathname).where("pathname LIKE ?", "#{root_pathname}#{PATHNAME_DELIMITER}%")
+      include_root ? scope.or(where(id: root)) : scope
+    end
   }
 
   # TODO: extract named functions to custom Arel extension

app/models/user.rb

@@ -29,4 +29,11 @@ class User < ApplicationRecord
   def at_least(status)
     User.statuses[self.status] >= User.statuses[status]
   end
+
+  # Returns true when this user is the only admin account in the system.
+  # Used to block actions that would leave the application without an admin
+  # (account deletion, status demotion).
+  def sole_admin?
+    admin? && !User.admin.where.not(id: id).exists?
+  end
 end

app/views/measurements/_measurement.html.erb

@@ -0,0 +1,14 @@
+<%= tag.tr id: dom_id(measurement) do %>
+  <td><%= l measurement.created_at, format: :short %></td>
+  <td>
+    <% measurement.readouts.each do |readout| %>
+      <span><%= readout.quantity.name %>: <%= readout.value %> <%= readout.unit %></span>
+    <% end %>
+  </td>
+  <% if current_user.at_least(:active) %>
+    <td class="actions">
+      <%= image_button_to t('.destroy'), 'delete-outline', measurement_path(measurement),
+        method: :delete %>
+    </td>
+  <% end %>
+<% end %>

app/views/measurements/create.turbo_stream.erb

@@ -0,0 +1,5 @@
+<%= turbo_stream.update :flashes %>
+<%= turbo_stream.remove :measurement_form %>
+<%= turbo_stream.remove :no_items %>
+<%= turbo_stream.enable :new_measurement_link %>
+<%= turbo_stream.prepend :measurements, @measurement %>

app/views/measurements/destroy.turbo_stream.erb

@@ -0,0 +1,3 @@
+<%= turbo_stream.update :flashes %>
+<%= turbo_stream.remove @measurement %>
+<%= turbo_stream.append(:measurements, render_no_items) if @measurements_empty %>

app/views/users/registrations/edit.html.erb

@@ -4,9 +4,8 @@
 <% end %>
 
 <div class="rightside-area buttongrid">
-  <%#= TODO: Disallow/disable deletion for last admin account, image_button_to_if %>
+  <%= image_button_to_if !current_user.sole_admin?, t('.delete'), 'account-remove-outline',
-  <%= image_button_to t('.delete'), 'account-remove-outline', user_registration_path,
+    user_registration_path, form_class: 'tools-area', method: :delete, data: {turbo: false},
-    form_class: 'tools-area', method: :delete, data: {turbo: false},
     onclick: {confirm: t('.confirm_delete')} %>
 </div>
 

config/credentials.yml.enc

@@ -1 +1 @@
-3nm9KZNtyLhPgZBVzOOkN2FXHD0uEMuzgb5Sl1MrAMmi6+iEFSzyTHfZFW2mz18VyNz5DDYvTODZqBDQKK+FQh70uEQkmGqaY5XsTOzUFzk56quaPNtZvFEGux1nX2avSbYQBs3HeyYyWyTAFhez5j8tVb6sZD2xZ8twa9KAB42j86NIHT9w/ZMFqZbGbdBoR1Mrqoy9/IWv2QgxMTpGR6JBpTUwauXm6wS/bTt8SCXF57JSVgvdw/BxFzoA3Xj6N5E89LbMfh54W2ruMhybka5E7zXN9z0v4oXt8GiYZFIODEYZwqzEVaUK1WXS5qb5OrDJFAzs29Uf/gDrIDx71Lot+jejCS+xFfI9454EnHcVH66wKuwF6ylKupJDffM0hQHplcEfVSq5UiDfbPXm46Vr0g1A--2RrmuzCBuHvYpPNA--ugbuRe7ivfDqeUCt6ahciA==
+OOGMGhfQuV67kqlMecZLcNfgrGS81KPAGmY27GnohtcGSPtiaqL8OZYsVf5IIOaI1K14ZEflln+E2deaIJ5apaq98f+1gJawGbAJeEfLCskJV/03nT8ICpRk+bxT/lzqeCIaUJOLk4708ufC9EpdpJD/jgVSAuI/iNMzzwMbNFvqNmx0Kmgp0mRpHSDGLZZkaP3GW7wdsJEVsNpSPIrkkGL1BvD+nHbmHjuGkn4MMsmm1Yz0M31jkJiDksT0SVeOcxWvOApclxm6VZOAws2l6YKEs/XoE7ye3ssjxdjdwjMzRXV7dwYclNBQGRoERVTozdYiFR4eAGMdlG0RsnUAp+edILH5nvHCIPb3la/dUTOzAQMNY0TqMMVUHGqGuVS/EMCX/w7zrmYN5C+2W8SfugrvTpAL--dUdvsDfbUdVrbmmo--fUwsWUp+DQGPtEF+Zq4ZTw==

config/locales/en.yml

@@ -88,6 +88,12 @@ en:
       select_quantity: select the measured quantities...
     index:
       new_measurement: Add measurement
+    create:
+      success: Measurement saved.
+    destroy:
+      success: Measurement deleted.
+    measurement:
+      destroy: Delete
   readouts:
     form:
       select_unit: ...
@@ -162,6 +168,9 @@ en:
           New password:
           <br><em>leave blank to keep unchanged</em>
           %{password_length_hint_html}
+  registrations:
+    destroy:
+      sole_admin: You cannot delete the only admin account.
   actions: Actions
   setup:
     new:

test/controllers/registrations_controller_test.rb

@@ -0,0 +1,18 @@
+require "test_helper"
+
+class RegistrationsControllerTest < ActionDispatch::IntegrationTest
+  test "sole admin cannot delete account" do
+    sign_in users(:admin)
+    delete user_registration_path
+    assert_redirected_to edit_user_registration_path
+    assert_equal t("registrations.destroy.sole_admin"), flash[:alert]
+    assert User.exists?(users(:admin).id)
+  end
+
+  test "non-admin can delete account" do
+    sign_in users(:alice)
+    assert_difference ->{ User.count }, -1 do
+      delete user_registration_path
+    end
+  end
+end

test/system/users_test.rb

@@ -149,7 +149,7 @@ class UsersTest < ApplicationSystemTestCase
   end
 
   test "delete profile" do
-    user = sign_in
+    user = sign_in user: users.reject(&:admin?).select(&:confirmed?).sample
     # TODO: remove condition after root_url changed to different path than
     # profile in routes.rb
     unless has_current_path?(edit_user_registration_path)
@@ -162,6 +162,14 @@ class UsersTest < ApplicationSystemTestCase
     assert_text t("devise.registrations.destroyed")
   end
 
+  test "sole admin cannot delete profile" do
+    sign_in user: users(:admin)
+    unless has_current_path?(edit_user_registration_path)
+      first(:link_or_button, users(:admin).email).click
+    end
+    assert find(:button, t("users.registrations.edit.delete"))[:disabled]
+  end
+
   test "index forbidden for non admin" do
     sign_in user: users.reject(&:admin?).select(&:confirmed?).sample
     visit users_path