Class: Volt::EachBinding

Inherits:
BaseBinding show all
Defined in:
lib/volt/page/bindings/each_binding.rb

Instance Attribute Summary

Attributes inherited from BaseBinding

#binding_name, #context, #target, #volt_app

Instance Method Summary collapse

Methods inherited from BaseBinding

#browser, #dom_section, #getter_fail, #remove_anchors

Constructor Details

#initialize(volt_app, target, context, binding_name, getter, variable_name, index_name, template_name) ⇒ EachBinding

Returns a new instance of EachBinding.



7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
 
# File 'lib/volt/page/bindings/each_binding.rb', line 7

def initialize(volt_app, target, context, binding_name, getter, variable_name, index_name, template_name)
  super(volt_app, target, context, binding_name)

  @item_name     = variable_name
  @index_name    = index_name
  @template_name = template_name

  @templates = []

  @getter      = getter

  # Listen for changes
  @computation = lambda do
    begin
      value = @context.instance_eval(&@getter)
    rescue => e
      Volt.logger.error("EachBinding Error: #{e.inspect}")
      if RUBY_PLATFORM == 'opal'
        Volt.logger.error(`#{@getter}`)
      else
        Volt.logger.error(e.backtrace.join("\n"))
      end

      value = []
    end

    value
  end.watch_and_resolve!(
    method(:update),
    method(:getter_fail)
  )
end

Instance Method Details

#current_values(values) ⇒ Object 



161
162
163
164
165
166
 
# File 'lib/volt/page/bindings/each_binding.rb', line 161

def current_values(values)
  return [] if values.is_a?(Model) || values.is_a?(Exception)
  values = values.attributes if values.respond_to?(:attributes)

  values
end

#item_added(position) ⇒ Object 



93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
 
# File 'lib/volt/page/bindings/each_binding.rb', line 93

def item_added(position)
  item_context = nil

  binding_name     = @@binding_number
  @@binding_number += 1

  if position >= @templates.size
    # Setup new bindings in the spot we want to insert the item
    dom_section.insert_anchor_before_end(binding_name)
  else
    # Insert the item before an existing item
    dom_section.insert_anchor_before(binding_name, @templates[position].binding_name)
  end

  # TODORW: parent: @value may change
  item_context                           = SubContext.new({ _index_value: position, parent: @value }, @context)
  item_context.locals[@item_name.to_sym] = proc do
    # Fetch only whats there currently, no promises.
    Volt.run_in_mode(:no_model_promises) do
      # puts "GET AT: #{item_context.locals[:_index_value]}"
      @value[item_context.locals[:_index_value]]
    end
  end

  position_dependency                    = Dependency.new
  item_context.locals[:_index_dependency] = position_dependency

  # Get and set index
  item_context.locals[:_index=]           = proc do |val|
    position_dependency.changed!
    item_context.locals[:_index_value] = val
  end

  # Get and set value
  value_dependency                    = Dependency.new
  item_context.locals["_#{@item_name}_dependency".to_sym] = value_dependency

  item_context.locals["#{@item_name}=".to_sym] = proc do |val|
    value_dependency.changed!
    @value[item_context.locals[:_index_value]] = val
  end

  # If the user provides an each_with_index, we can assign the lookup for the index
  # variable here.
  if @index_name
    item_context.locals[@index_name.to_sym] = proc do
      position_dependency.depend
      item_context.locals[:_index_value]
    end
  end

  item_template = TemplateRenderer.new(@volt_app, @target, item_context, binding_name, @template_name)
  @templates.insert(position, item_template)

  update_indexes_after(position)
end

#item_removed(position) ⇒ Object 



80
81
82
83
84
85
86
87
88
89
90
91
 
# File 'lib/volt/page/bindings/each_binding.rb', line 80

def item_removed(position)
  # Remove dependency
  @templates[position].context.locals[:_index_dependency].remove
  @templates[position].context.locals["_#{@item_name}_dependency".to_sym].remove

  @templates[position].remove_anchors
  @templates[position].remove
  @templates.delete_at(position)

  # Removed at the position, update context for every item after this position
  update_indexes_after(position)
end

#remove ⇒ Object

When this each_binding is removed, cleanup.



180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
 
# File 'lib/volt/page/bindings/each_binding.rb', line 180

def remove
  @computation.stop
  @computation = nil

  # Clear value
  @value       = []

  @getter = nil

  remove_listeners

  if @templates
    template_count = @templates.size
    template_count.times do |index|
      item_removed(template_count - index - 1)
    end
    # @templates.compact.each(&:remove)
    @templates = nil
  end

  super
end

#remove_listeners ⇒ Object 



168
169
170
171
172
173
174
175
176
177
 
# File 'lib/volt/page/bindings/each_binding.rb', line 168

def remove_listeners
  if @added_listener
    @added_listener.remove
    @added_listener = nil
  end
  if @removed_listener
    @removed_listener.remove
    @removed_listener = nil
  end
end

#update(value) ⇒ Object

When a changed event happens, we update to the new size.



41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
 
# File 'lib/volt/page/bindings/each_binding.rb', line 41

def update(value)
  # Since we're checking things like size, we don't want this to be re-triggered on a
  # size change, so we run without tracking.
  Computation.run_without_tracking do
    # Adjust to the new size
    values = current_values(value)

    @value = values

    remove_listeners

    if @value.respond_to?(:on)
      @added_listener   = @value.on('added') { |position| item_added(position) }
      @removed_listener = @value.on('removed') { |position| item_removed(position) }
    end

    templates_size = nil
    values_size = nil

    Volt.run_in_mode(:no_model_promises) do
      templates_size = @templates.size

      unless values.respond_to?(:size)
        fail InvalidObjectForEachBinding, "Each binding's require an object that responds to size and [] methods.  The binding received: #{values.inspect}"
      end

      values_size    = values.size
    end

    # Start over, re-create all nodes
    (templates_size - 1).downto(0) do |index|
      item_removed(index)
    end
    0.upto(values_size - 1) do |index|
      item_added(index)
    end
  end
end

#update_indexes_after(start_index) ⇒ Object

When items are added or removed in the middle of the list, we need to update each templates index value.



152
153
154
155
156
157
158
159
 
# File 'lib/volt/page/bindings/each_binding.rb', line 152

def update_indexes_after(start_index)
  size = @templates.size
  if size > 0
    start_index.upto(size - 1) do |index|
      @templates[index].context.locals[:_index=].call(index)
    end
  end
end