Merge pull request #673 from moofkit/rule_error_with_args

adds support of explict argument for #rule_error? method

[changelog]

added: "You can now pass a key name or path to `rule_error?` predicate (issue #658 closed via #673) (@moofkit)"

docsite/source/rules.html.md

@@ -238,6 +238,28 @@ FooContract.new.(foo: 'foo').errors.to_h
 # { foo: ['failure added', 'failure added after checking'] }
 ```
 
+Also it is possible for checking other rule error by passing explicit argument to `rule_error?` method
+
+```ruby
+class PersonContract < Dry::Validation::Contract
+  schema do
+    required(:email).filled(:string)
+    required(:name).filled(:string)
+  end
+
+  rule(:name) do
+    key.failure('name rule error')
+  end
+
+  rule(:email) do
+    key.failure('email rule error') if rule_error?(:name)
+  end
+end
+
+PersonContract.new.call(email: 'bar', name: 'foo').errors.to_h
+# {name: ['name rule error'], email: ['email rule error']}
+```
+
 ### Defining a rule for each element of an array
 
 To check each element of an array you can simply use `Rule#each` shortcut. It works just like a normal rule, which means it's only applied when a value passed schema checks and supports setting failure messages in the standard way.

lib/dry/validation/evaluator.rb

@@ -187,11 +187,17 @@ def schema_error?(path)
 
       # Check if there are any errors on the current rule
       #
+      # @param path [Symbol, String, Array] A Path-compatible spec
+      #
       # @return [Boolean]
       #
       # @api public
-      def rule_error?
-        !key(path).empty?
+      def rule_error?(path = nil)
+        if path.nil?
+          !key(self.path).empty?
+        else
+          result.rule_error?(path)
+        end
       end
 
       # @api private

lib/dry/validation/result.rb

@@ -113,6 +113,13 @@ def schema_error?(key)
         schema_result.error?(key)
       end
 
+      # Check if the rules includes an error for the provided key
+      #
+      # @api private
+      def rule_error?(key)
+        !schema_error?(key) && error?(key)
+      end
+
       # Check if there's any error for the provided key
       #
       # This does not consider errors from the nested values

spec/integration/contract/evaluator/errors_spec.rb

@@ -24,23 +24,56 @@
   end
 
   describe "#rule_error?" do
-    let(:contract) do
-      Class.new(Dry::Validation::Contract) do
-        schema do
-          required(:foo).filled(:string)
-        end
+    context "without argument" do
+      let(:contract) do
+        Class.new(Dry::Validation::Contract) do
+          schema do
+            required(:foo).filled(:string)
+          end
 
-        rule(:foo) do
-          key.failure("failure added")
-          key.failure("failure added after checking") if rule_error?
+          rule(:foo) do
+            key.failure("failure added")
+            key.failure("failure added after checking") if rule_error?
+          end
         end
       end
+
+      it "checks for errors in current rule" do
+        expect(contract.new.(foo: "some@email.com").errors.to_h).to eql(
+          foo: ["failure added", "failure added after checking"]
+        )
+      end
     end
 
-    it "checks for errors in current rule" do
-      expect(contract.new.(foo: "some@email.com").errors.to_h).to eql(
-        foo: ["failure added", "failure added after checking"]
-      )
+    context "with argument" do
+      let(:contract) do
+        Class.new(Dry::Validation::Contract) do
+          schema do
+            required(:name).filled(:string)
+            required(:email).filled(:string)
+          end
+
+          rule(:name) do
+            key.failure("expected")
+          end
+
+          rule(:email) do
+            key.failure("also expected") if rule_error?(:name)
+          end
+        end
+      end
+
+      it "checks for error in rule with name provided in argument" do
+        expect(contract.new.(name: "John", email: "some@email.com").errors.to_h).to eql(
+          {name: ["expected"], email: ["also expected"]}
+        )
+      end
+
+      it "does not evaluate if schema with provided key is falling down" do
+        expect(contract.new.(name: nil, email: "some@email.com").errors.to_h).to eql(
+          {name: ["must be a string"]}
+        )
+      end
     end
   end
 end