Pro Android with Kotlin

97
CHAPTER 6: Content Providers

FLAG_SUPPORTS_RECENTS (root can be queried to show recently changed 
documents)

FLAG_SUPPORTS_SEARCH (the tree allows for searching documents)

COLUMN_ICON (int): Icon resource ID for a root. Required.

COLUMN_MIME_TYPES (string): Supported MIME types. If more than one, use a 
newline \n as a separator. Optional, and may be null to indicate support for 
all MIME types.

COLUMN_ROOT_ID (string): A unique ID of the root. Required.

COLUMN_SUMMARY (string): Summary for this root; might be shown to a user. 
Optional, and may be null to indicate “unknown.”

COLUMN_TITLE (string): Title for the root, might be shown to a user. Required.
If this set of roots changes, you must call ContentResolver.notifyChange with 
DocumentsContract.buildRootsUri to notify the system.

override fun queryChildDocuments(parentDocumentId: String?, 
projection: Array?, sortOrder: String?): Cursor:
Return the immediate children documents and subdirectories contained in the requested 
directory. Apps targeting at API level 26 or higher should instead implement fun queryChil
dDocuments(parentDocumentId: String?, projection: Array?, queryArgs: 
Bundle?): Cursor and in this method use the following:
override fun queryChildDocuments(
parentDocumentId: String?,
projection: Array?,
sortOrder: String?): Cursor {
val bndl = Bundle()
bndl.putString(
ContentResolver.QUERY_ARG_SQL_SORT_ORDER,
sortOrder)
return queryChildDocuments(
parentDocumentId, projection, bndl)
}

override fun queryChildDocuments(parentDocumentId: String?, 
projection: Array?, queryArgs: Bundle?): Cursor:
Return the immediate children documents and subdirectories contained in the requested 
directory. The bundle argument contains query parameters as keys.
ContentResolver.QUERY_ARG_SQL_SELECTION
ContentResolver.QUERY_ARG_SQL_SELECTION_ARGS
ContentResolver.QUERY_ARG_SQL_SORT_ORDER -or-
ContentResolver.QUERY_ARG_SORT_COLUMNS
(this being a String array)

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