add support for selective JSON and YAML serialization (crystal-lang#9567

)

* add support for selective JSON and YAML serialization

* fix yaml serialization spec

* fix yaml serialization spec again

my bad for copy and pasting

Co-authored-by: Brian J. Cardiff <[email protected]>

spec/std/json/serializable_spec.cr

@@ -332,6 +332,21 @@ struct JSONAttrPersonWithYAMLInitializeHook
   end
 end
 
+struct JSONAttrPersonWithSelectiveSerialization
+  include JSON::Serializable
+
+  property name : String
+
+  @[JSON::Field(ignore_serialize: true)]
+  property password : String
+
+  @[JSON::Field(ignore_deserialize: true)]
+  property generated : String = "generated-internally"
+
+  def initialize(@name : String, @password : String)
+  end
+end
+
 abstract class JSONShape
   include JSON::Serializable
 
@@ -834,6 +849,16 @@ describe "JSON mapping" do
     JSONAttrPersonWithYAMLInitializeHook.from_yaml(person.to_yaml).msg.should eq "Hello Vasya"
   end
 
+  it "json with selective serialization" do
+    person = JSONAttrPersonWithSelectiveSerialization.new("Vasya", "P@ssw0rd")
+    person.to_json.should eq "{\"name\":\"Vasya\",\"generated\":\"generated-internally\"}"
+
+    person_json = "{\"name\":\"Vasya\",\"generated\":\"should not set\",\"password\":\"update\"}"
+    person = JSONAttrPersonWithSelectiveSerialization.from_json(person_json)
+    person.generated.should eq "generated-internally"
+    person.password.should eq "update"
+  end
+
   describe "use_json_discriminator" do
     it "deserializes with discriminator" do
       point = JSONShape.from_json(%({"type": "point", "x": 1, "y": 2})).as(JSONPoint)

spec/std/yaml/serializable_spec.cr

@@ -67,6 +67,21 @@ class YAMLAttrPersonEmittingNull
   property age : Int32?
 end
 
+struct YAMLAttrPersonWithSelectiveSerialization
+  include YAML::Serializable
+
+  property name : String
+
+  @[YAML::Field(ignore_serialize: true)]
+  property password : String
+
+  @[YAML::Field(ignore_deserialize: true)]
+  property generated : String = "generated-internally"
+
+  def initialize(@name : String, @password : String)
+  end
+end
+
 @[YAML::Serializable::Options(emit_nulls: true)]
 class YAMLAttrPersonEmittingNullsByOptions
   include YAML::Serializable
@@ -410,6 +425,16 @@ describe "YAML::Serializable" do
     ex.location.should eq({3, 1})
   end
 
+  it "works with selective serialization" do
+    person = YAMLAttrPersonWithSelectiveSerialization.new("Vasya", "P@ssw0rd")
+    person.to_yaml.should eq "---\nname: Vasya\ngenerated: generated-internally\n"
+
+    person_yaml = "---\nname: Vasya\ngenerated: should not set\npassword: update\n"
+    person = YAMLAttrPersonWithSelectiveSerialization.from_yaml(person_yaml)
+    person.generated.should eq "generated-internally"
+    person.password.should eq "update"
+  end
+
   it "does to_yaml" do
     person = YAMLAttrPerson.from_yaml("---\nname: John\nage: 30\n")
     person2 = YAMLAttrPerson.from_yaml(person.to_yaml)

src/json/serialization.cr

@@ -60,6 +60,8 @@ module JSON
   #
   # `JSON::Field` properties:
   # * **ignore**: if `true` skip this field in serialization and deserialization (by default false)
+  # * **ignore_serialize**: if `true` skip this field in serialization (by default false)
+  # * **ignore_deserialize**: if `true` skip this field in deserialization (by default false)
   # * **key**: the value of the key in the json object (by default the name of the instance variable)
   # * **root**: assume the value is inside a JSON object with a given key (see `Object.from_json(string_or_io, root)`)
   # * **converter**: specify an alternate type for parsing and generation. The converter must define `from_json(JSON::PullParser)` and `to_json(value, JSON::Builder)` as class methods. Examples of converters are `Time::Format` and `Time::EpochConverter` for `Time`.
@@ -158,7 +160,7 @@ module JSON
         {% properties = {} of Nil => Nil %}
         {% for ivar in @type.instance_vars %}
           {% ann = ivar.annotation(::JSON::Field) %}
-          {% unless ann && ann[:ignore] %}
+          {% unless ann && (ann[:ignore] || ann[:ignore_deserialize]) %}
             {%
               properties[ivar.id] = {
                 type:        ivar.type,
@@ -266,7 +268,7 @@ module JSON
         {% properties = {} of Nil => Nil %}
         {% for ivar in @type.instance_vars %}
           {% ann = ivar.annotation(::JSON::Field) %}
-          {% unless ann && ann[:ignore] %}
+          {% unless ann && (ann[:ignore] || ann[:ignore_serialize]) %}
             {%
               properties[ivar.id] = {
                 type:      ivar.type,

src/yaml/serialization.cr

@@ -60,6 +60,8 @@ module YAML
   #
   # `YAML::Field` properties:
   # * **ignore**: if `true` skip this field in serialization and deserialization (by default false)
+  # * **ignore_serialize**: if `true` skip this field in serialization (by default false)
+  # * **ignore_deserialize**: if `true` skip this field in deserialization (by default false)
   # * **key**: the value of the key in the yaml object (by default the name of the instance variable)
   # * **converter**: specify an alternate type for parsing and generation. The converter must define `from_yaml(YAML::ParseContext, YAML::Nodes::Node)` and `to_yaml(value, YAML::Nodes::Builder)` as class methods. Examples of converters are `Time::Format` and `Time::EpochConverter` for `Time`.
   # * **presence**: if `true`, a `@{{key}}_present` instance variable will be generated when the key was present (even if it has a `null` value), `false` by default
@@ -164,7 +166,7 @@ module YAML
         {% properties = {} of Nil => Nil %}
         {% for ivar in @type.instance_vars %}
           {% ann = ivar.annotation(::YAML::Field) %}
-          {% unless ann && ann[:ignore] %}
+          {% unless ann && (ann[:ignore] || ann[:ignore_deserialize]) %}
             {%
               properties[ivar.id] = {
                 type:        ivar.type,
@@ -270,7 +272,7 @@ module YAML
         {% properties = {} of Nil => Nil %}
         {% for ivar in @type.instance_vars %}
           {% ann = ivar.annotation(::YAML::Field) %}
-          {% unless ann && ann[:ignore] %}
+          {% unless ann && (ann[:ignore] || ann[:ignore_serialize]) %}
             {%
               properties[ivar.id] = {
                 type:      ivar.type,