Generate assertValues function

- allow skipping fields using "ignoreField"
- allow skipping field from assertValues using "ignoreAssertValues"

Forms/Forms.stencil

@@ -5,28 +5,46 @@
 import Forms
 
 extension {{ type.localName }} {
-    internal var fields: [FieldType] {
+    {{ type.accessLevel }} var fields: [FieldType] {
         return [
-{% for variable in type.variables where variable.typeName|hasPrefix:"FormField<" %}
-            {{ variable.name }},
+{% for variable in type.variables where variable.typeName|hasPrefix:"FormField<" and variable|!annotated:"ignoreField" %}
+            {{ variable.name }}{% if not forloop.last %},{% endif %}
 {% endfor %}
         ]
     }
 }
 
-internal protocol {{ type.localName }}FieldsType {
-{% for variable in type.variables where variable.typeName|hasPrefix:"FormField<" %}
-    var {{ variable.name|replace:"Field",""}}: {{variable.typeName.name|replace:"FormField<",""|replace:">",""}}? { get }
+extension {{ type.localName }} {
+{% for variable in type.variables where variable.typeName|hasPrefix:"FormField<" and variable|!annotated:"ignoreField" %}
+    {{ type.accessLevel }} var {{ variable.name|replace:"Field",""}}: {{variable.typeName.name|replace:"FormField<",""|replace:">",""}}? {
+        return {{ variable.name }}.value
+    }
 {% endfor %}
 }
 
-extension {{ type.localName }}: {{ type.localName }}FieldsType {
-{% for variable in type.variables where variable.typeName|hasPrefix:"FormField<" %}
-    var {{ variable.name|replace:"Field",""}}: {{variable.typeName.name|replace:"FormField<",""|replace:">",""}}? {
-        return {{ variable.name }}.value
-    }
+{% if type|!annotated:"ignoreAssertValues" %}
+extension {{ type.localName }} {
+    {{ type.accessLevel }} func assertValues(errorOnNil: Error = Abort(.internalServerError)) throws -> (
+{% for variable in type.variables where variable.typeName|hasPrefix:"FormField<" and variable|!annotated:"ignoreAssertValues" and variable|!annotated:"ignoreField" %}
+        {%if not forloop.last or not forloop.first %}{{ variable.name|replace:"Field",""}}: {% endif %}{{variable.typeName.name|replace:"FormField<",""|replace:">",""}}{% if not forloop.last %},{% endif %}
+{% endfor %}
+    ) {
+        guard
+{% for variable in type.variables where variable.typeName|hasPrefix:"FormField<" and variable|!annotated:"ignoreAssertValues" and variable|!annotated:"ignoreField" %}
+            let {{ variable.name|replace:"Field",""}} = {{ variable.name|replace:"Field",""}}{% if not forloop.last %},{% endif %}
 {% endfor %}
+        else {
+            throw errorOnNil
+        }
+
+        return (
+{% for variable in type.variables where variable.typeName|hasPrefix:"FormField<" and variable|!annotated:"ignoreAssertValues" and variable|!annotated:"ignoreField" %}
+            {{ variable.name|replace:"Field",""}}{% if not forloop.last %},{% endif %}
+{% endfor %}
+        )
+    }
 }
 
+{% endif %}
 // sourcery:end
 {% endfor %}