update-groups.md

Update groups

This library provides the GroupsUpdate API that allows you to update existing Groups.

An instance of the GroupsUpdate API is obtained by,

val update = Contacts(context).groups().update()

A basic update

To update an existing group,

val updateResult = Contacts(context)
    .groups()
    .update()
    .groups(existingGroup?.mutableCopy {
        title = "Best Friends"
    })
    .commit()

If you need to update multiple groups,

val mutableGroup1 = group1.mutableCopy { ... }
val mutableGroup2 = group2.mutableCopy { ... }

val updateResult = Contacts(context)
    .groups()
    .update()
    .groups(mutableGroup1, mutableGroup2)
    .commit()

Read-only Groups

Groups created by the system are typically read-only. You cannot modify them, even if you try! The Contacts Provider typically have the following system groups (for standard Google Accounts),

• systemId: Contacts, title: My Contacts
• systemId: null, title: Starred in Android
• systemId: Friends, title: Friends
• systemId: Family, title: Family
• systemId: Coworkers, title: Coworkers

The above list may vary per Account and/or flavor of Android.

If you are implementing a sync adapter, you may be able to update read-only groups associated with the Account that your sync adapter works with. For more info, read Contacts API Setup | Sync adapter operations.

Groups and duplicate titles

The Contacts Provider allows multiple groups with the same title (case-sensitive comparison) belonging to the same (nullable) account to exist. In older versions of Android, the AOSP Contacts app allows the creation of new groups with existing titles. In newer versions, duplicate titles are not allowed. Therefore, this library does not allow for duplicate titles.

Executing the update

To execute the update,

.commit()

Handling the update result

The commit function returns a Result.

To check if all updates succeeded,

val allUpdatesSuccessful = updateResult.isSuccessful

To check if a particular update succeeded,

val firstUpdateSuccessful = updateResult.isSuccessful(mutableGroup1)

Handling update failure

The update may fail for a particular group for various reasons,

updateResult.failureReason(mutableGroup1)?.let {
    when (it) {
        TITLE_ALREADY_EXIST -> promptUserToPickDifferentTitle()
        GROUP_IS_READ_ONLY -> informUserThatReadOnlyGroupsCannotBeModified()
        UNKNOWN -> showGenericErrorMessage()
    }   
}

Cancelling the update

To cancel an update amid execution,

.commit { returnTrueIfUpdateShouldBeCancelled() }

The commit function optionally takes in a function that, if it returns true, will cancel update processing as soon as possible. The function is called numerous times during update processing to check if processing should stop or continue. This gives you the option to cancel the update.

For example, to automatically cancel the update inside a Kotlin coroutine when the coroutine is cancelled,

launch {
    withContext(coroutineContext) {
        val updateResult = update.commit { !isActive }
    }
}

Performing the update and result processing asynchronously

Updates are executed when the commit function is invoked. The work is done in the same thread as the call-site. This may result in a choppy UI.

To perform the work in a different thread, use the Kotlin coroutine extensions provided in the async module. For more info, read Execute work outside of the UI thread using coroutines.

You may, of course, use other multi-threading libraries or just do it yourself =)

ℹ️ Extensions for Kotlin Flow and RxJava are also in the project roadmap.

Performing the update with permission

Updates require the android.permission.WRITE_CONTACTS. If not granted, the update will do nothing and return a failed result.

To perform the update with permission, use the extensions provided in the permissions module. For more info, read Permissions handling using coroutines.

You may, of course, use other permission handling libraries or just do it yourself =)