Importing

The import() method copies the specified archive to a temporary location, then opens it and extracts the specified stores (or all stores if none are specified) & all necessary tiles, merging them into the in-use database. The specified archive must exist, must be valid, and should contain all the specified stores, if applicable.

import method - RootExternal class - flutter_map_tile_caching library - Dart APIpub.dev

There is no support for directly overwriting the in-use database with the archived database, but this may be performed manually while FMTC is uninitialised.

There must be enough storage space available on the device to duplicate the entire archive, and to potentially grow the in-use database.

This is done to preserve the original archive, as this operation writes to the temporary archive. The temporary archive is deleted after the import has completed.

final importResult =
    await FMTCRoot.external('~/path/to/file.fmtc').import(['storeName']);

The returned value is complex. See the API documentation for more details:

ImportResult typedef - flutter_map_tile_caching library - Dart APIpub.dev

Conflict Resolution Strategies

If an importing store has the same name as an existing store, a conflict has occurred, because stores must have unique names. FMTC provides 4 resolution strategies:

• skip Skips importing the store

• replace Deletes the existing store, replacing it entirely with the importing store

• rename Appends the current date and time to the name of the importing store, to make it unique

• merge Merges the two stores' tiles and metadata together

In any case, a conflict between tiles will result in the newer (most recently modified) tile winning (it is assumed it is more up-to-date).

ImportConflictStrategy enum - flutter_map_tile_caching library - Dart APIpub.dev

List Stores

If the user must be given a choice as to which stores to import (or it is helpful to know), and it is unknown what the stores within the archive are, the listStores getter will list the available store names without performing an import.

The same storage pitfalls as import exist. listStores must also duplicate the entire archive.

listStores property - RootExternal class - flutter_map_tile_caching library - Dart APIpub.dev