diff --git a/src/main/scala/app/CreateRepositoryServlet.scala b/src/main/scala/app/CreateRepositoryServlet.scala
index f620ab3..0a3665c 100644
--- a/src/main/scala/app/CreateRepositoryServlet.scala
+++ b/src/main/scala/app/CreateRepositoryServlet.scala
@@ -1,6 +1,7 @@
 package app
 
 import util.Directory._
+import util.Validations._
 import org.scalatra._
 import java.io.File
 import org.eclipse.jgit.api.Git
@@ -23,11 +24,8 @@
    * Create new repository.
    */
   post("/") {
-    withValidation(validate, params){
-      val repositoryName = params("name")
-      val description = params("description")
-    
-      val gitdir = getRepositoryDir(LoginUser, repositoryName)
+    withValidation(form, params){ form =>
+      val gitdir = getRepositoryDir(LoginUser, form.name)
       val repository = new RepositoryBuilder().setGitDir(gitdir).setBare.build
     
       repository.create
@@ -36,16 +34,16 @@
       config.setBoolean("http", null, "receivepack", true)
       config.save
     
-      val tmpdir = getInitRepositoryDir(LoginUser, repositoryName)
+      val tmpdir = getInitRepositoryDir(LoginUser, form.name)
       try {
         // Clone the repository
         Git.cloneRepository.setURI(gitdir.toURI.toString).setDirectory(tmpdir).call
     
         // Create README.md
-        FileUtils.writeStringToFile(new File(tmpdir, "README.md"), if(description.nonEmpty){
-            repositoryName + "\n===============\n\n" + description
+        FileUtils.writeStringToFile(new File(tmpdir, "README.md"), if(form.description.nonEmpty){
+            form.name + "\n===============\n\n" + form.description
           } else {
-            repositoryName + "\n===============\n"
+            form.name + "\n===============\n"
           }, "UTF-8")
     
         val git = Git.open(tmpdir)
@@ -58,25 +56,32 @@
       }
       
       // redirect to the repository
-      redirect("/%s/%s".format(LoginUser, repositoryName))
+      redirect("/%s/%s".format(LoginUser, form.name))
     }
   }
   
   get("/validate") {
     contentType = "application/json"
-    validate(params).toJSON
+    form.validateAsJSON(params)
   }
   
-  def validate(params: Map[String, String]): ValidationResult = {
-    val name = params("name")
-    if(name.isEmpty){
-      ValidationResult(false, Map("name" -> "Repository name is required."))
-    } else if(!name.matches("^[a-z0-6\\-_]+$")){
-      ValidationResult(false, Map("name" -> "Repository name contans invalid character."))
-    } else if(getRepositories(LoginUser).contains(name)){
-      ValidationResult(false, Map("name" -> "Repository already exists."))
-    } else {
-      ValidationResult(true, Map.empty)
+  val form = Form(
+      "name"        -> trim(label("Repository name", text(required, maxlength(40), repository))), 
+      "description" -> trim(label("Description"    , text()))
+  )(RepositoryCreationForm.apply)
+
+  def repository: Constraint = new Constraint(){
+    def validate(name: String, value: String): Option[String] = {
+      if(!value.matches("^[a-z0-9\\-_]+$")){
+        Some("Repository name contains invalid character.")
+      } else if(getRepositories(LoginUser).contains(value)){
+        Some("Repository already exists.")
+      } else {
+        None
+      }
     }
   }
+  
+  case class RepositoryCreationForm(name: String, description: String)
+  
 }
\ No newline at end of file
diff --git a/src/main/scala/app/ServletBase.scala b/src/main/scala/app/ServletBase.scala
index 8f5cd04..2f6af60 100644
--- a/src/main/scala/app/ServletBase.scala
+++ b/src/main/scala/app/ServletBase.scala
@@ -15,22 +15,4 @@
   // TODO get from session
   val LoginUser = System.getProperty("user.name")
   
-  protected def withValidation(validator: Map[String, String] => ValidationResult, params: Map[String, String])(action: => Any): Any = {
-    validator(params).valid match {
-      case true  => action
-      case false => throw new RuntimeException("Invalid Request") // TODO show error page?
-    }
-  }
-  
-  case class ValidationResult(valid: Boolean, errors: Map[String, String]){
-    def toJSON(): JObject = {
-      JObject(
-        "valid"  -> JBool(valid),
-        "errors" -> JObject(errors.map { case (key, value) =>
-          JField(key, JString(value))
-        }.toList)
-      )
-    }
-  }
-
 }
\ No newline at end of file
diff --git a/src/main/scala/util/Validations.scala b/src/main/scala/util/Validations.scala
new file mode 100644
index 0000000..0019214
--- /dev/null
+++ b/src/main/scala/util/Validations.scala
@@ -0,0 +1,118 @@
+package util
+
+import org.json4s._
+import org.json4s.jackson._
+
+object Validations {
+  
+  def withValidation[T](form: Form[T], params: Map[String, String])(action: T => Any): Any = {
+    form.validate(params).isEmpty match {
+      case true  => action(form.create(params))
+      case false => throw new RuntimeException("Invalid Request") // TODO show error page?
+    }
+  }
+  
+  def Form[T, P1](f1: (String, ValueType[P1]))(factory: (P1) => T): Form[T] = new Form[T]{
+    def fields = Seq(f1)
+    def create(params: Map[String, String]) = factory(f1._2.convert(params(f1._1)))
+  }
+  
+  def Form[T, P1, P2](f1: (String, ValueType[P1]), f2: (String, ValueType[P2]))(factory: (P1, P2) => T): Form[T] = new Form[T]{
+    def fields = Seq(f1, f2)
+    def create(params: Map[String, String]) = factory(f1._2.convert(params(f1._1)), f2._2.convert(params(f2._1)))
+  }
+  
+  def Form[T, P1, P2, P3](f1: (String, ValueType[P1]), f2: (String, ValueType[P2]), f3: (String, ValueType[P3]))(factory: (P1, P2, P3) => T): Form[T] = new Form[T]{
+    def fields = Seq(f1, f2)
+    def create(params: Map[String, String]) = factory(f1._2.convert(params(f1._1)), f2._2.convert(params(f2._1)), f3._2.convert(params(f3._1)))
+  }
+  
+  abstract class Form[T] {
+    
+    def fields: Seq[(String, ValueType[_])]
+    
+    def create(params: Map[String, String]): T
+    
+    def validate(params: Map[String, String]): Map[String, String] = {
+      fields.map { case (name, valueType) =>
+        valueType.validate(name, params(name)) match {
+          case Some(message) => Some(name, message)
+          case None => None
+        }
+      }.flatten.toMap
+    }
+    
+    def validateAsJSON(params: Map[String, String]): JObject = {
+      JObject(validate(params).map { case (key, value) =>
+        JField(key, JString(value))
+      }.toList)
+    }
+  }
+  
+  /////////////////////////////////////////////////////////////////////////////////////////////
+  // Constraints
+  
+  trait Constraint {
+    def validate(name: String, value: String): Option[String]
+  }
+  
+  def required: Constraint = new Constraint(){
+    def validate(name: String, value: String): Option[String] = 
+      if(value.isEmpty) Some("%s is required.".format(name)) else None
+  }
+  
+  def required(message: String): Constraint = new Constraint(){
+    def validate(name: String, value: String): Option[String] = 
+      if(value.isEmpty) Some(message) else None
+  }
+  
+  def maxlength(length: Int): Constraint = new Constraint(){
+    def validate(name: String, value: String): Option[String] =
+      if(value.length > length) Some("%s cannot be longer than %d characters.".format(name, length)) else None
+  }
+  
+  def minlength(length: Int): Constraint = new Constraint(){
+    def validate(name: String, value: String): Option[String] =
+      if(value.length < length) Some("%s cannot be shorter than %d characters".format(name, length)) else None
+  }
+  
+  def pattern(pattern: String, message: String = ""): Constraint = new Constraint {
+    def validate(name: String, value: String): Option[String] =
+      if(!value.matches("^" + pattern + "$")){
+        if(message.isEmpty) Some("%s must be '%s'.".format(name, pattern)) else Some(message)
+      } else None
+  }
+  
+  /////////////////////////////////////////////////////////////////////////////////////////////
+  // ValueTypes
+  
+  abstract class ValueType[T](constraints: Constraint*) {
+    
+    def convert(value: String): T
+    
+    def validate(name: String, value: String): Option[String] = {
+      constraints.map(_.validate(name, value)).flatten.headOption
+    }
+  }
+  
+  def text(constraints: Constraint*): ValueType[String] = new ValueType[String](constraints: _*){
+    def convert(value: String): String = value
+  }
+  
+  /////////////////////////////////////////////////////////////////////////////////////////////
+  // ValueType wrappers to provide additional features.
+  
+  def trim[T](valueType: ValueType[T]): ValueType[T] = new ValueType[T](){
+    def convert(value: String): T = valueType.convert(value.trim)
+    override def validate(name: String, value: String): Option[String] = valueType.validate(name, value.trim)
+  }
+  
+  /**
+   * 
+   */
+  def label[T](label: String, valueType: ValueType[T]): ValueType[T] = new ValueType[T](){
+    def convert(value: String): T = valueType.convert(value.trim)
+    override def validate(name: String, value: String): Option[String] = valueType.validate(label, value.trim)
+  }
+  
+}
\ No newline at end of file
diff --git a/src/main/webapp/assets/common/js/validation.js b/src/main/webapp/assets/common/js/validation.js
index 330f22c..1e37e6e 100644
--- a/src/main/webapp/assets/common/js/validation.js
+++ b/src/main/webapp/assets/common/js/validation.js
@@ -16,11 +16,11 @@
 		// clear all error messages
 		$('.error-message').text('');
 		
-		if(data.valid){
+		if($.isEmptyObject(data)){
 			form.data('validated', true);
 			form.submit();
 		} else {
-			$.each(data.errors, function(key, value){
+			$.each(data, function(key, value){
 				$('#error-' + key).text(value);
 			});
 		}