vargasgabriel · May 20, 2021 02:02 · May 20, 2021 · May 20, 2021 · May 19, 2021 · Mar 30, 2021
diff --git a/ViewModel.kt b/ViewModel.kt
@@ -1,17 +1,16 @@
-val biometric = MutableLiveData<Agreement>()
-val biometricValidator = LiveDataValidator<Agreement>( biometric ).apply{
-    addRule( messageOf("must acept or decline") ){ it == null }
-    addRule( messageOf( "must accept or devline")){ it == Agreement.Agreed }
+val password = MutableLiveData<String>()
+val passwordValidator = LiveDataValidator<String>(password).apply{
+    addRule("password is required") { it.isNullOrBlank() }
+    addRule("password length must be 7") { it?.length != 7 }
 }
 
-val isAgreementFormValid = MediatorLiveData<Boolean>()
-
-init {
-    isAgreementFormValid.value = false
-    isAgreementFormValid.addSource(biometric){ validateForm() }
+val isFormValid = MediatorLiveData<Boolean>().apply {
+    value = false
+    addSource(username) { value = validateForm() }
 }
 
-fun validateForm(){
-    val validators = listOf( biometricValidator )
-    isAgreementFormValid.value = validators.all { it.isValid() }
+private fun validateForm() : Boolean {
+    val validators = listOf(passwordValidator)
+    val validatorResolver = LiveDataValidatorResolver(validators)
+    return validatorResolver.isValid()
 }
diff --git a/LiveDataValidator.kt b/LiveDataValidator.kt
@@ -1,20 +1,24 @@
+// https://oozou.com/blog/modern-android-form-validations-with-data-binding-147
+
+typealias Predicate<T> = (value: T?) -> Boolean
+
 class LiveDataValidator<T>(private val liveData: LiveData<T>){
-    private val validationRules = mutableListOf< (T?) -> Boolean >()
-    private val errorMessages = mutableListOf< Message >()
+    private val validationRules = mutableListOf<Predicate<T>>()
+    private val errorMessages = mutableListOf<String>()
 
     var error = MutableLiveData<Message?>()
 
-    fun addRule(errorMsg: Message, predicate: (T?) -> Boolean ){
+    fun addRule(errorMsg: String, predicate: Predicate<T>) {
         validationRules.add(predicate)
         errorMessages.add(errorMsg)
     }
 
-    private fun emitErrorMessage(message: Message?){
-        error.value = message
+    private fun emitErrorMessage(messageRes: String?) {
+        error.value = messageRes
     }
 
     fun isValid(): Boolean {
-        for( i in 0 until validationRules.size){
+        for(i in 0 until validationRules.size){
             if(validationRules[i](liveData.value) ){
                 emitErrorMessage(errorMessages[i])
                 return false

diff --git a/LiveDataValidator.kt b/LiveDataValidator.kt
@@ -15,7 +15,7 @@ class LiveDataValidator<T>(private val liveData: LiveData<T>){
 
     fun isValid(): Boolean {
         for( i in 0 until validationRules.size){
-            if( ! validationRules[i](liveData.value) ){
+            if(validationRules[i](liveData.value) ){
                 emitErrorMessage(errorMessages[i])
                 return false
             }

diff --git a/LiveDataValidator.kt b/LiveDataValidator.kt
@@ -0,0 +1,27 @@
+class LiveDataValidator<T>(private val liveData: LiveData<T>){
+    private val validationRules = mutableListOf< (T?) -> Boolean >()
+    private val errorMessages = mutableListOf< Message >()
+
+    var error = MutableLiveData<Message?>()
+
+    fun addRule(errorMsg: Message, predicate: (T?) -> Boolean ){
+        validationRules.add(predicate)
+        errorMessages.add(errorMsg)
+    }
+
+    private fun emitErrorMessage(message: Message?){
+        error.value = message
+    }
+
+    fun isValid(): Boolean {
+        for( i in 0 until validationRules.size){
+            if( ! validationRules[i](liveData.value) ){
+                emitErrorMessage(errorMessages[i])
+                return false
+            }
+        }
+
+        emitErrorMessage(null)
+        return true
+    }
+}
diff --git a/LiveDataValidatorResolver.kt b/LiveDataValidatorResolver.kt
@@ -0,0 +1,3 @@
+class LiveDataValidatorResolver(private val validators: List<LiveDataValidator<*>>){
+    fun isValid() : Boolean = validators.all { it.isValid() }
+}
diff --git a/ViewModel.kt b/ViewModel.kt
@@ -0,0 +1,17 @@
+val biometric = MutableLiveData<Agreement>()
+val biometricValidator = LiveDataValidator<Agreement>( biometric ).apply{
+    addRule( messageOf("must acept or decline") ){ it == null }
+    addRule( messageOf( "must accept or devline")){ it == Agreement.Agreed }
+}
+
+val isAgreementFormValid = MediatorLiveData<Boolean>()
+
+init {
+    isAgreementFormValid.value = false
+    isAgreementFormValid.addSource(biometric){ validateForm() }
+}
+
+fun validateForm(){
+    val validators = listOf( biometricValidator )
+    isAgreementFormValid.value = validators.all { it.isValid() }
+}
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