Created
March 30, 2021 20:42
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Form validation with LiveData
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| 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 | |
| } | |
| } |
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| class LiveDataValidatorResolver(private val validators: List<LiveDataValidator<*>>){ | |
| fun isValid() : Boolean = validators.all { it.isValid() } | |
| } |
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| 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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