Chapter 14 Update Persons
In the last chapter we covered the create-part of our CRUD app for persons. In this chapter we now want to enable the user to update existing persons (for example to correct data or change a person’s image). You will notice that our toolset starts to simplify our coding life! Let’s start with a view model for our update page:
14.1 UpdatePersonViewModel.kt
package app.gedama.tutorial.cruddiary.viewmodel
import android.database.sqlite.SQLiteConstraintException
import androidx.lifecycle.*
import app.gedama.tutorial.cruddiary.dao.PersonDao
import app.gedama.tutorial.cruddiary.data.Gender
import app.gedama.tutorial.cruddiary.data.Person
import app.gedama.tutorial.cruddiary.data.Spinnable
import kotlinx.coroutines.launch
import java.util.*
class UpdatePersonViewModel(personId: Long, val personDao: PersonDao) : BaseViewModel() {
val person = personDao.get(personId)
val allGenders = personDao.getAllGenders(1L)
val allGendersAndPersonLiveData: LiveData<Pair<List<Gender>, Person>> =
object: MediatorLiveData<Pair<List<Gender>, Person>>() {
var allG: List<Gender>? = null
var pers: Person? = null
init {
addSource( allGenders ) { allG ->
this.allG = allG
pers?.let { value = allG to it }
}
addSource(person) { pers ->
this.pers = pers
allG?.let { value = it to pers }
}
}
}
val _newBirthdate = MutableLiveData<Date>()
val newBirthdate: LiveData<Date>
get() = _newBirthdate
fun updatePerson() {
_doValidation.value = true
}
override fun updateEntryAfterValidation() {
viewModelScope.launch {
if ( deactivateSuccess.value!! || person.value!!.inactive ) {
person.value!!.inactive = true
} else {
person.value!!.inactive = false
}
val newImagePath = checkNewImagePath("person_")
newImagePath?.let {
person.value!!.imagePath = it
}
try {
personDao.update(person.value!!)
_navigateToList.value = true
} catch(sqlExc: SQLiteConstraintException) {
_insertSuccess.value = false
_deactivateSuccess.value = false
}
}
}
fun deactivatePerson() {
_deactivateSuccess.value = true
_doValidation.value = true
}
fun updateGender(item: Spinnable) {
person.value!!.genderId = item.itemId()
}
fun updateBirthdate(updatedDate: Date) {
_newBirthdate.value = updatedDate
person.value!!.birthDate = updatedDate
}
}
class UpdatePersonViewModelFactory(private val personId: Long, private val personDao:PersonDao) : ViewModelProvider.Factory {
override fun <T : ViewModel> create(modelClass: Class<T>): T {
if (modelClass.isAssignableFrom(UpdatePersonViewModel::class.java)) {
return UpdatePersonViewModel(personId, personDao) as T
}
throw java.lang.IllegalArgumentException("Unknown ViewModel")
}
}
Analogous to our view model for updating genders, we have a separate Factory-class which is passed a PersonDao object and the ID of the person item that gets updated at initialization. The variable person gets our existing person object from the database. As with our view model for adding new person items, we have to validate the user input and check for database constraint violations.
14.2 string.xml (English)
For our user interface, we have to add a couple of string values to our string.xml files:
<resources>
<string name="app_name">CrudDiary</string>
<string name="nothing_selected" translatable="false">---</string>
<string name="male_gender">male</string>
<string name="female_gender">female</string>
<string name="diverse_gender">diverse</string>
<string name="main_menu_title">Home</string>
<string name="persons_list_menu_title">Persons</string>
<string name="persons_add_menu_title">Add person</string>
<string name="persons_update_menu_title">Update person</string>
<string name="tags_list_menu_title">Tags</string>
<string name="diary_entries_list_menu_title">Diary entries</string>
<string name="genders_list_menu_title">Genders</string>
<string name="genders_add_menu_title">Add gender</string>
<string name="genders_update_menu_title">Update gender</string>
<string name="help_menu_title">Help</string>
<string name="support_section">Support</string>
<string name="preferences_menu_title">Preferences</string>
<string name="import_export_menu_title">Import/Export</string>
<string name="search_view_hint">Search entries</string>
<string name="fab_add_description">Add entry</string>
<string name="fab_filter_description">Filter entries</string>
<string name="fab_csv_description">Export entries to CSV file</string>
<string name="name_label">Name</string>
<string name="save_button">Save</string>
<string name="deactivate_button">Deactivate</string>
<string name="delete_button">Delete</string>
<string name="update_button">Update</string>
<string name="unique_gender_violation">This gender name already exists!</string>
<string name="unique_person_violation">This person already exists!</string>
<string name="validation_no_name">Name is required</string>
<string name="validation_no_title">Title is required</string>
<string name="validation_no_birthdate">Birthdate is required</string>
<string name="validation_no_gender">Gender is required</string>
<string name="inactive_label">Inactive</string>
<string name="inactivity_safety_dialog_title">Safety check</string>
<string name="inactivity_safety_check">Actually deactivate entry?</string>
<string name="yes">Yes</string>
<string name="no">No</string>
<string name="no_entries">You either have not created any entries yet or there are no entries matching your search/filter criteria.</string>
<string name="item_image_description">Assigned image</string>
<string name="add_image_button">Add image</string>
<string name="change_image_button">Change image</string>
<string name="delete_image_button">Delete image</string>
<string name="image_picking_canceled">Image picking canceled</string>
<string name="person_gender_label">Gender</string>
<string name="person_birthdate_label">Birthdate</string>
</resources>
Next we define the layout for our new fragment.
14.3 fragment_update_person.xml
<?xml version="1.0" encoding="utf-8"?>
<layout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context="app.gedama.tutorial.cruddiary.framgent.EditPersonFragment">
<data>
<variable
name="viewModel"
type="app.gedama.tutorial.cruddiary.viewmodel.UpdatePersonViewModel" />
</data>
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.appcompat.widget.LinearLayoutCompat
style="@style/CrudDiary_LinearLayoutCompat">
<include
android:id="@+id/name_text_field_binding"
app:viewModelValue="@={viewModel.person.name}"
layout="@layout/text_input_name" />
<include
android:id="@+id/birthdate_text_field_binding"
app:hintText="@{@string/person_birthdate_label}"
app:viewModelValue="@={viewModel.person.birthDateAsString}"
layout="@layout/text_input_date" />
<include
android:id="@+id/spinner_genders_binding"
app:textHint="@{@string/person_gender_label}"
layout="@layout/spinner_generic" />
<include
android:id="@+id/check_box_binding"
app:viewModelValue="@={viewModel.person.inactive}"
layout="@layout/checkbox_inactive" />
<include
android:id="@+id/image_area_binding"
layout="@layout/image_area" />
<include
app:viewModelFunc="@{ () -> viewModel.updatePerson() }"
android:id="@+id/crud_buttons"
app:visibility="@{android.view.View.VISIBLE}"
layout="@layout/crud_buttons" />
</androidx.appcompat.widget.LinearLayoutCompat>
</ScrollView>
</layout>
Notice the similarity of this file to the one we used for adding new persons! Next we want to extend our navigation graph with our new fragment:
14.4 nav_graph.xml
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/nav_graph"
app:startDestination="@id/homeFragment">
<fragment
android:id="@+id/homeFragment"
android:name="app.gedama.tutorial.cruddiary.fragment.HomeFragment"
android:label="@string/main_menu_title" >
<action
android:id="@+id/action_homeFragment_to_gendersListFragment"
app:destination="@id/gendersListFragment" />
<action
android:id="@+id/action_homeFragment_to_personsListFragment"
app:destination="@id/personsListFragment" />
</fragment>
<fragment
android:id="@+id/gendersListFragment"
android:name="app.gedama.tutorial.cruddiary.fragment.GendersListFragment"
android:label="@string/genders_list_menu_title"
tools:layout="@layout/fragment_genders_list" >
<action
android:id="@+id/action_gendersListFragment_to_homeFragment"
app:destination="@id/homeFragment" />
<action
android:id="@+id/action_gendersListFragment_to_addGenderFragment"
app:destination="@id/addGenderFragment" />
<action
android:id="@+id/action_gendersListFragment_to_updateGenderFragment"
app:destination="@id/updateGenderFragment" />
</fragment>
<fragment
android:id="@+id/addGenderFragment"
android:name="app.gedama.tutorial.cruddiary.fragment.AddGenderFragment"
android:label="@string/genders_add_menu_title" >
<action
android:id="@+id/action_addGenderFragment_to_gendersListFragment"
app:destination="@id/gendersListFragment"
app:popUpTo="@id/homeFragment" />
</fragment>
<fragment
android:id="@+id/updateGenderFragment"
android:name="app.gedama.tutorial.cruddiary.fragment.UpdateGenderFragment"
android:label="@string/genders_update_menu_title" >
<action
android:id="@+id/action_updateGenderFragment_to_gendersListFragment"
app:destination="@id/gendersListFragment"
app:popUpTo="@id/homeFragment" />
<argument
android:name="genderId"
app:argType="long" />
</fragment>
<fragment
android:id="@+id/personsListFragment"
android:name="app.gedama.tutorial.cruddiary.fragment.PersonsListFragment"
android:label="@string/persons_list_menu_title"
tools:layout="@layout/fragment_persons_list" >
<action
android:id="@+id/action_personsListFragment_to_homeFragment"
app:destination="@id/homeFragment" />
<action
android:id="@+id/action_personsListFragment_to_addPersonFragment"
app:destination="@id/addPersonFragment" />
<action
android:id="@+id/action_personsListFragment_to_updatePersonFragment"
app:destination="@id/updatePersonFragment" />
</fragment>
<fragment
android:id="@+id/addPersonFragment"
android:name="app.gedama.tutorial.cruddiary.fragment.AddPersonFragment"
android:label="@string/persons_add_menu_title" >
<action
android:id="@+id/action_addPersonFragment_to_personsListFragment"
app:destination="@id/personsListFragment"
app:popUpTo="@id/homeFragment" />
</fragment>
<fragment
android:id="@+id/updatePersonFragment"
android:name="app.gedama.tutorial.cruddiary.fragment.UpdatePersonFragment"
android:label="@string/persons_update_menu_title" >
<action
android:id="@+id/action_updatePersonFragment_to_personsListFragment"
app:destination="@id/personsListFragment"
app:popUpTo="@id/homeFragment" />
<argument
android:name="personId"
app:argType="long" />
</fragment>
</navigation>
Note that we added the argument personId to our new fragment because we have to pass the ID so we know which person item gets updated. Now it is time to present our UpdatePersonFragment class:
14.5 UpdatePersonFragment.kt
package app.gedama.tutorial.cruddiary.fragment
import android.app.DatePickerDialog
import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.lifecycle.*
import androidx.lifecycle.Observer
import app.gedama.tutorial.cruddiary.R
import androidx.navigation.findNavController
import app.gedama.tutorial.cruddiary.data.Spinnable
import app.gedama.tutorial.cruddiary.data.Validation
import app.gedama.tutorial.cruddiary.database.CrudDiaryDatabase
import app.gedama.tutorial.cruddiary.databinding.FragmentUpdatePersonBinding
import app.gedama.tutorial.cruddiary.ui.LambdaDatePicker
import app.gedama.tutorial.cruddiary.ui.formfields.FormFieldText
import app.gedama.tutorial.cruddiary.viewmodel.UpdatePersonViewModel
import app.gedama.tutorial.cruddiary.viewmodel.UpdatePersonViewModelFactory
import com.google.android.material.snackbar.Snackbar
import java.text.DateFormat
import java.util.*
class UpdatePersonFragment: BaseFragment() {
private var _binding: FragmentUpdatePersonBinding? = null
private val binding get() = _binding!!
lateinit var viewModel: UpdatePersonViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
_binding = FragmentUpdatePersonBinding.inflate(inflater, container, false)
val view = binding.root
val personId = UpdatePersonFragmentArgs.fromBundle(requireArguments()).personId
val application = requireNotNull(this.activity).application
val personDao = CrudDiaryDatabase.getInstance(application).personDao
val viewModelFactory = UpdatePersonViewModelFactory(personId,personDao)
viewModel = ViewModelProvider(this, viewModelFactory)[UpdatePersonViewModel::class.java]
binding.viewModel = viewModel
binding.lifecycleOwner = viewLifecycleOwner
// form validation, see https://medium.com/@asissuthar/simplify-form-validation-using-kotlin-flow-on-android-16c718e3efaa
val fieldName = FormFieldText(
scope = lifecycleScope,
textInputLayout = binding.nameTextFieldBinding.nameLayout,
textInputEditText = binding.nameTextFieldBinding.name,
Validation.nameValidation
)
val fieldBirthday = FormFieldText(
scope = lifecycleScope,
textInputLayout = binding.birthdateTextFieldBinding.dateLayout,
textInputEditText = binding.birthdateTextFieldBinding.date,
Validation.birthdayValidation
)
val fieldGender = FormFieldText(
scope = lifecycleScope,
textInputLayout = binding.spinnerGendersBinding.spinnerInputLayoutId,
textInputEditText = binding.spinnerGendersBinding.spinnerTextId,
Validation.genderValidation
)
val formFields = listOf(fieldName,fieldBirthday,fieldGender)
initImagePicking(binding.imageAreaBinding.imageView, binding.imageAreaBinding.buttonLoadPicture,viewModel, binding.imageAreaBinding.buttonDefaultPicture)
saveToUpdateButton(binding.crudButtons.actionButton)
viewModel.navigateToList.observe(viewLifecycleOwner, Observer { navigate ->
if (navigate) {
view.findNavController()
.navigate(R.id.action_updatePersonFragment_to_personsListFragment)
viewModel.onNavigatedToList()
}
})
viewModel.allGendersAndPersonLiveData.observe(viewLifecycleOwner, Observer { (allg,pers) ->
val genderId = pers.genderId ?: 1L
val currentGender = allg.find{ it.genderId == genderId }
val currentGenderPos = allg.indexOf(currentGender)
binding.spinnerGendersBinding.spinnerId.setSelection(currentGenderPos)
} )
viewModel.person.observe(viewLifecycleOwner, Observer { item ->
if ( item.birthDate != null ) {
binding.birthdateTextFieldBinding.date.setText(DateFormat.getDateInstance(DateFormat.MEDIUM).format(item.birthDate!!))
}
setChangeImageButton(view, item.imagePath, viewModel)
setInactivityButton(item.inactive,binding.crudButtons.deactivateButton,binding.checkBoxBinding.checkBoxInactive)
})
viewModel.newBirthdate.observe(viewLifecycleOwner, Observer { item ->
binding.birthdateTextFieldBinding.date.setText(DateFormat.getDateInstance(DateFormat.MEDIUM).format(item))
})
viewModel.doValidation.observe(viewLifecycleOwner, Observer { doValidate ->
if (doValidate) {
formValidation(binding.crudButtons.actionButton, formFields, viewModel)
}
})
viewModel.insertSuccess.observe(viewLifecycleOwner, Observer { isSuccess ->
if (isSuccess != null && !isSuccess ) {
Snackbar.make(binding.crudButtons.actionButton,resources.getText(R.string.unique_person_violation),
Snackbar.LENGTH_INDEFINITE).show()
Log.d(TAG,"There was a problem when updating person data in the database ...")
}
})
@Suppress("UNCHECKED_CAST")
initMaterialSpinnerData(binding.spinnerGendersBinding.spinnerId,binding.spinnerGendersBinding.spinnerTextId,
viewModel.allGenders as LiveData<List<Spinnable>>,{ item: Spinnable -> viewModel.updateGender(item)} )
binding.birthdateTextFieldBinding.date.setOnClickListener(handleIconClick)
binding.birthdateTextFieldBinding.dateLayout.setEndIconOnClickListener(handleIconClick)
setDeleteImageButton(binding.imageAreaBinding.buttonDefaultPicture,binding.imageAreaBinding.imageView,
binding.imageAreaBinding.imageViewContainer,binding.imageAreaBinding.buttonLoadPicture, viewModel)
setDeactivateButton(binding.crudButtons.deactivateButton, { viewModel.deactivatePerson() } )
return view
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
private val handleIconClick = object : View.OnClickListener {
override fun onClick(v: View?) {
val picker = LambdaDatePicker(context!!, showTimePicker = false, { item: Date -> viewModel.updateBirthdate(item) })
val currentBirthdate = Calendar.getInstance()
viewModel.person.value?.birthDate?.let {
currentBirthdate.time = viewModel.person.value!!.birthDate!!
}
val datePickerDialog =
DatePickerDialog(
context!!,
picker,
currentBirthdate.get(Calendar.YEAR),
currentBirthdate.get(
Calendar.MONTH
),
currentBirthdate.get(Calendar.DAY_OF_MONTH)
)
datePickerDialog.datePicker.maxDate = Date().time
datePickerDialog.show()
}
}
}
Once again, for getting from the persons list page to the ’Update person’ page, we have to extend our existing PersonsListFragment:
14.6 PersonsListFragment.kt
...
viewModel.navigateToAddItem.observe(viewLifecycleOwner, Observer { navigate ->
if ( navigate ) {
val action = PersonsListFragmentDirections
.actionPersonsListFragmentToAddPersonFragment()
this.findNavController().navigate(action)
viewModel.onItemAddNavigated()
}
})
viewModel.navigateToEditItem.observe(viewLifecycleOwner, Observer { personId ->
personId?.let {
val action = PersonsListFragmentDirections
.actionPersonsListFragmentToUpdatePersonFragment(personId)
this.findNavController().navigate(action)
viewModel.onItemEditNavigated()
}
})
return view
...
With all these new files and extensions of existing files, the code should now rebuild and run on a (virtual) device. If you tap on one of the items in the persons list, you get to the input mask for updating the selected person (see Figure 14.1). Notice the image buttons below Lucy’s picture: We have a ’Change image’ button and a ’Delete image’ button.
If you tap onto the ’Delete image’ button, the existing picture vanishes and we end up with a single button called ’Add image’ (see Figure 14.2).
If the validation of our updated person was successful, the logic returns to the persons list and displays the updated person values (alternate picture, birthdate was changed - see Figure 11.2).
