Feature: rendering optional attributes

lib/props_template.rb

@@ -22,6 +22,7 @@ class << self
     self.template_lookup_options = {handlers: [:props]}
 
     delegate :result!, :array!,
+      :optional!,
       :deferred!,
       :fragments!,
       :set_block_content!,

lib/props_template/base.rb

@@ -7,9 +7,12 @@ class InvalidScopeForArrayError < StandardError; end
   class InvalidScopeForObjError < StandardError; end
 
   class Base
+    attr_accessor :contains
+
     def initialize(encoder = nil)
       @stream = Oj::StringWriter.new(mode: :rails)
       @scope = nil
+      @contains = nil
     end
 
     def set_block_content!(options = {})
@@ -87,6 +90,21 @@ def handle_collection(collection, options)
       end
     end
 
+    # builds structure of rendered optional attributes as hash
+    def transform_contain_keys(values)
+      return {} if values.blank?
+
+      values.each_with_object({}) do |item, acc|
+        if item.is_a?(Hash)
+          item.each do |key, value|
+            acc[key] = transform_contain_keys(value)
+          end
+        else
+          acc[item] = :present
+        end
+      end
+    end
+
     # todo, add ability to define contents of array
     def array!(collection, options = {})
       if @scope.nil?
@@ -105,6 +123,21 @@ def array!(collection, options = {})
       nil
     end
 
+    # value should be lambda to avoid calculations before optional check
+    # if attribute should be rendered then call set with calculated value
+    def optional!(key, value = nil, &block)
+      return set!(key, value ? value.call : {}, &block) if contains.blank?
+
+      # traveled path without arra indexes
+      path = traveled_path.select { |item| item.is_a?(Symbol) }
+      # render if
+      # 1) "contains" hash contains key at required nesting
+      # 2) "contains" hash contains parent key at required nesting with all rendering attributes
+      render_attribute = contains.dig(*(path + [key])) || path.size > 0 && contains.dig(*path) == {}
+
+      set!(key, value ? value.call : {}, &block) if render_attribute
+    end
+
     def result!
       if @scope.nil?
         @stream.push_object

lib/props_template/base_with_extensions.rb

@@ -7,6 +7,7 @@ def initialize(builder, context = nil, options = {})
       @builder = builder
       @em = ExtensionManager.new(self)
       @traveled_path = []
+
       super()
     end
 

lib/props_template/extensions/partial_renderer.rb

@@ -140,6 +140,11 @@ def refine_options(options, item = nil)
       locals = (rest[:locals] || {}).clone
       rest[:locals] = locals
 
+      if rest
+        @base.contains ||= @base.transform_contain_keys(rest.dig(:locals, :contains))
+        rest[:locals][:contains] = @base.contains
+      end
+
       if item
         as = if !rest[:as]
           retrieve_variable(partial)

lib/props_template/searcher.rb

@@ -1,7 +1,10 @@
 module Props
   class Searcher
+    attr_accessor :contains
     attr_reader :builder, :context, :fragments, :traveled_path
 
+    delegate :transform_contain_keys, to: :builder!
+
     def initialize(builder, path = [], context = nil)
       @search_path = path
       @depth = 0
@@ -10,9 +13,14 @@ def initialize(builder, path = [], context = nil)
       @found_options = nil
       @builder = builder
       @traveled_path = []
+      @contains = nil
       @partialer = Partialer.new(self, context, builder)
     end
 
+    def builder!
+      @builder
+    end
+
     def deferred!
       []
     end

spec/extensions/partial_render_spec.rb

@@ -323,4 +323,70 @@
 
     expect(json).to eql_json([])
   end
+
+  context "when locals with contains" do
+    it "renders only required attributes" do
+      json = render(<<~PROPS)
+        emails = [
+          {value: '[email protected]'},
+          {value: '[email protected]'},
+        ]
+        json.array! emails, partial: ['optional', locals: {contains: [:email]}] do
+        end
+      PROPS
+
+      expect(json).to eql_json([
+        {email: "[email protected]"},
+        {email: "[email protected]"}
+      ])
+    end
+
+    it "renders object with all nested attributes" do
+      json = render(<<~PROPS)
+        emails = [
+          {value: '[email protected]'},
+          {value: '[email protected]'},
+        ]
+        json.array! emails, partial: ['optional', locals: {contains: [emailAsObject: []]}] do
+        end
+      PROPS
+
+      expect(json).to eql_json([
+        {emailAsObject: {email: "[email protected]", something: nil}},
+        {emailAsObject: {email: "[email protected]", something: nil}}
+      ])
+    end
+
+    it "renders object with only required nested attributes" do
+      json = render(<<~PROPS)
+        emails = [
+          {value: '[email protected]'},
+          {value: '[email protected]'},
+        ]
+        json.array! emails, partial: ['optional', locals: {contains: [emailAsObject: [:email]]}] do
+        end
+      PROPS
+
+      expect(json).to eql_json([
+        {emailAsObject: {email: "[email protected]"}},
+        {emailAsObject: {email: "[email protected]"}}
+      ])
+    end
+
+    it "renders all attributes" do
+      json = render(<<~PROPS)
+        emails = [
+          {value: '[email protected]'},
+          {value: '[email protected]'},
+        ]
+        json.array! emails, partial: ['optional', locals: {contains: [:email, {emailAsObject: [:email]}, :something]}] do
+        end
+      PROPS
+
+      expect(json).to eql_json([
+        {email: "[email protected]", something: nil, emailAsObject: {email: "[email protected]"}},
+        {email: "[email protected]", something: nil, emailAsObject: {email: "[email protected]"}}
+      ])
+    end
+  end
 end

spec/fixtures/_optional.json.props

@@ -0,0 +1,7 @@
+json.optional! :email, -> { optional[:value] }
+json.optional! :something, -> { nil }
+
+json.optional! :emailAsObject do
+  json.optional! :email, -> { optional[:value] }
+  json.optional! :something, -> { nil }
+end

spec/props_template_spec.rb

@@ -296,4 +296,52 @@
       }.to raise_error(Props::InvalidScopeForArrayError)
     end
   end
+
+  context "optional!" do
+    it "sets a value" do
+      json = Props::Base.new
+      json.optional! :foo, -> { "bar" }
+      attrs = json.result!.strip
+
+      expect(attrs).to eql_json({
+        foo: "bar"
+      })
+    end
+
+    it "sets a empty obj when block is empty" do
+      json = Props::Base.new
+      json.optional! :foo do
+      end
+      attrs = json.result!.strip
+
+      expect(attrs).to eql_json({
+        foo: {}
+      })
+    end
+
+    it "sets a empty obj when nested block is empty" do
+      json = Props::Base.new
+      json.optional! :foo do
+        json.optional! :bar do
+        end
+      end
+      attrs = json.result!.strip
+
+      expect(attrs).to eql_json({
+        foo: {
+          bar: {}
+        }
+      })
+    end
+
+    it "sets a null value" do
+      json = Props::Base.new
+      json.optional! :foo, -> { nil }
+      attrs = json.result!.strip
+
+      expect(attrs).to eql_json({
+        foo: nil
+      })
+    end
+  end
 end