Add JSON support to UUID (#5551)

Author: lachlan

spec/std/json/mapping_spec.cr

@@ -1,5 +1,7 @@
 require "spec"
 require "json"
+require "uuid"
+require "uuid/json"
 require "big/json"
 
 private class JSONPerson
@@ -32,6 +34,10 @@ private class JSONWithBool
   JSON.mapping value: Bool
 end
 
+private class JSONWithUUID
+  JSON.mapping value: UUID
+end
+
 private class JSONWithBigDecimal
   JSON.mapping value: BigDecimal
 end
@@ -249,6 +255,12 @@ describe "JSON mapping" do
     json.value.should be_false
   end
 
+  it "parses UUID" do
+    uuid = JSONWithUUID.from_json(%({"value": "ba714f86-cac6-42c7-8956-bcf5105e1b81"}))
+    uuid.should be_a(JSONWithUUID)
+    uuid.value.should eq(UUID.new("ba714f86-cac6-42c7-8956-bcf5105e1b81"))
+  end
+
   it "parses json with Time::Format converter" do
     json = JSONWithTime.from_json(%({"value": "2014-10-31 23:37:16"}))
     json.value.should be_a(Time)

spec/std/json/serialization_spec.cr

@@ -2,6 +2,8 @@ require "spec"
 require "json"
 require "big"
 require "big/json"
+require "uuid"
+require "uuid/json"
 
 enum JSONSpecEnum
   Zero
@@ -91,6 +93,24 @@ describe "JSON serialization" do
       big.should eq(BigFloat.new("1234"))
     end
 
+    it "does for UUID (hyphenated)" do
+      uuid = UUID.from_json("\"ee843b26-56d8-472b-b343-0b94ed9077ff\"")
+      uuid.should be_a(UUID)
+      uuid.should eq(UUID.new("ee843b26-56d8-472b-b343-0b94ed9077ff"))
+    end
+
+    it "does for UUID (hex)" do
+      uuid = UUID.from_json("\"ee843b2656d8472bb3430b94ed9077ff\"")
+      uuid.should be_a(UUID)
+      uuid.should eq(UUID.new("ee843b26-56d8-472b-b343-0b94ed9077ff"))
+    end
+
+    it "does for UUID (urn)" do
+      uuid = UUID.from_json("\"urn:uuid:ee843b26-56d8-472b-b343-0b94ed9077ff\"")
+      uuid.should be_a(UUID)
+      uuid.should eq(UUID.new("ee843b26-56d8-472b-b343-0b94ed9077ff"))
+    end
+
     it "does for BigDecimal from int" do
       big = BigDecimal.from_json("1234")
       big.should be_a(BigDecimal)
@@ -281,6 +301,11 @@ describe "JSON serialization" do
       big = BigFloat.new("1234.567891011121314")
       big.to_json.should eq("1234.567891011121314")
     end
+
+    it "does for UUID" do
+      uuid = UUID.new("ee843b26-56d8-472b-b343-0b94ed9077ff")
+      uuid.to_json.should eq("\"ee843b26-56d8-472b-b343-0b94ed9077ff\"")
+    end
   end
 
   describe "to_pretty_json" do

src/docs_main.cr

@@ -57,5 +57,6 @@ require "./string_scanner"
 require "./tempfile"
 require "./uri"
 require "./uuid"
+require "./uuid/json"
 require "./zip"
 require "./zlib"

src/uuid/json.cr

@@ -0,0 +1,30 @@
+require "json"
+require "uuid"
+
+# Adds JSON support to `UUID` for use in a JSON mapping.
+#
+# NOTE: `require "uuid/json"` is required to opt-in to this feature.
+#
+# ```
+# require "json"
+# require "uuid"
+# require "uuid/json"
+#
+# class Example
+#   JSON.mapping id: UUID
+# end
+#
+# example = Example.from_json(%({"id": "ba714f86-cac6-42c7-8956-bcf5105e1b81"}))
+#
+# uuid = UUID.new("87b3042b-9b9a-41b7-8b15-a93d3f17025e")
+# uuid.to_json # => "87b3042b-9b9a-41b7-8b15-a93d3f17025e"
+# ```
+struct UUID
+  def self.new(pull : JSON::PullParser)
+    new(pull.read_string)
+  end
+
+  def to_json(json : JSON::Builder)
+    json.string(to_s)
+  end
+end