More accurately parse json values for params

spec/lucky/params_spec.cr

@@ -386,6 +386,16 @@ describe Lucky::Params do
       params.nested?(:user).should eq({"name" => "Bunyan", "age" => "102", "active" => "true"})
     end
 
+    it "gets nested JSON containing nested JSON" do
+      request = build_request body: {user: {name: "Paul", address: {home: "1600 Pennsylvania Ave"}}}.to_json,
+        content_type: "application/json"
+      request.query = "from=query"
+
+      params = Lucky::Params.new(request)
+
+      params.nested?(:user).should eq({"name" => "Paul", "address" => "{\"home\":\"1600 Pennsylvania Ave\"}"})
+    end
+
     it "gets nested multipart params" do
       request = build_multipart_request form_parts: {
         "user" => {

src/lucky/params.cr

@@ -411,7 +411,7 @@ class Lucky::Params
     nested_key_json = parsed_json[nested_key]? || JSON::Any.new({} of String => JSON::Any)
 
     nested_key_json.as_h.each do |key, value|
-      nested_params[key.to_s] = value.to_s
+      nested_params[key.to_s] = stringify_json_value(value)
     end
 
     nested_params
@@ -423,7 +423,7 @@ class Lucky::Params
 
     nested_key_json.as_h.each do |key, value|
       if array_value = value.as_a?
-        nested_params[key.to_s] = array_value.map(&.to_s)
+        nested_params[key.to_s] = array_value.map { |array_val| stringify_json_value(array_val) }
       end
     end
 
@@ -535,7 +535,7 @@ class Lucky::Params
     nested_key_json.as_a.each do |nested_values|
       nested_params = {} of String => String
       nested_values.as_h.each do |key, value|
-        nested_params[key.to_s] = value.to_s
+        nested_params[key.to_s] = stringify_json_value(value)
       end
 
       many_nested_params << nested_params
@@ -573,7 +573,7 @@ class Lucky::Params
 
   private def body_param(key : String)
     if json?
-      parsed_json[key]?.try(&.to_s)
+      parsed_json[key]?.try { |value| stringify_json_value(value) }
     elsif multipart?
       multipart_params[key]?
     else
@@ -654,4 +654,8 @@ class Lucky::Params
       nil
     end
   end
+
+  private def stringify_json_value(value : JSON::Any) : String
+    value.as_s? || value.to_json
+  end
 end