Parse request body params only if content type is application/x-www-form-urlencoded

spec/param_parser_spec.cr

@@ -18,8 +18,36 @@ describe "ParamParser" do
       hasan = env.params["hasan"]
       "Hello #{name} #{hasan} #{age}"
     end
-    request = HTTP::Request.new("POST", "/?hasan=cemal", body: "name=serdar&age=99")
+
+    request = HTTP::Request.new(
+      "POST",
+      "/?hasan=cemal",
+      body: "name=serdar&age=99",
+      headers: HTTP::Headers{"Content-Type": "application/x-www-form-urlencoded"},
+    )
+
     params = Kemal::ParamParser.new(route, request).parse
     params.should eq({"hasan" => "cemal", "name" => "serdar", "age" => "99"})
   end
+
+  context "when content type is incorrect" do
+    it "does not parse request body" do
+      route = Route.new "POST", "/" do |env|
+        name = env.params["name"]
+        age = env.params["age"]
+        hasan = env.params["hasan"]
+        "Hello #{name} #{hasan} #{age}"
+      end
+
+      request = HTTP::Request.new(
+        "POST",
+        "/?hasan=cemal",
+        body: "name=serdar&age=99",
+        headers: HTTP::Headers{"Content-Type": "text/plain"},
+      )
+
+      params = Kemal::ParamParser.new(route, request).parse
+      params.should eq({"hasan" => "cemal"})
+    end
+  end
 end

src/kemal/param_parser.cr

@@ -2,6 +2,8 @@
 # and converts them into a params hash which you can within the environment
 # context.
 class Kemal::ParamParser
+  URL_ENCODED_FORM = "application/x-www-form-urlencoded"
+
   def initialize(@route, @request)
     @route_components = route.components
     @request_components = request.path.not_nil!.split "/"
@@ -14,16 +16,27 @@ class Kemal::ParamParser
   end
 
   def parse_request
-    {% for part in %w(query body) %}
+    parse_query
-      if {{part.id}} = @request.{{part.id}}
+    parse_body
-        HTTP::Params.parse({{part.id}}) do |key, value|
-          @params[key] ||= value
-        end
-      end
-    {% end %}
     @params
   end
 
+  def parse_body
+    return unless @request.headers["Content-Type"]? == URL_ENCODED_FORM
+    parse_part(@request.body)
+  end
+
+  def parse_query
+    parse_part(@request.query)
+  end
+
+  def parse_part(part)
+    return unless part
+    HTTP::Params.parse(part) do |key, value|
+      @params[key] ||= value
+    end
+  end
+
   def parse_components
     @route_components.zip(@request_components) do |route_component, req_component|
       if route_component.starts_with? ':'