Migrator
public
abstract
class
Migrator
extends Object
java.lang.Object | |
↳ | android.app.appsearch.Migrator |
A migrator class to translate GenericDocument
from different version of AppSearchSchema
Make non-backwards-compatible changes will delete all stored documents in old schema. You can
save your documents by setting Migrator
via the SetSchemaRequest.Builder.setMigrator(String, Migrator)
for each type and target version you want to save.
onDowngrade(int, int, GenericDocument)
or onUpgrade(int, int, GenericDocument)
will be triggered if the version number of the
schema stored in AppSearch is different with the version in the request.
If any error or Exception occurred in the onDowngrade(int, int, GenericDocument)
or onUpgrade(int, int, GenericDocument)
, all the
setSchema request will be rejected unless the schema changes are backwards-compatible, and stored
documents won't have any observable changes.
Summary
Public constructors | |
---|---|
Migrator()
|
Public methods | |
---|---|
abstract
GenericDocument
|
onDowngrade(int currentVersion, int finalVersion, GenericDocument document)
Migrates |
abstract
GenericDocument
|
onUpgrade(int currentVersion, int finalVersion, GenericDocument document)
Migrates |
abstract
boolean
|
shouldMigrate(int currentVersion, int finalVersion)
Returns |
Inherited methods | |
---|---|
Public constructors
Public methods
onDowngrade
public abstract GenericDocument onDowngrade (int currentVersion, int finalVersion, GenericDocument document)
Migrates GenericDocument
to an older version of AppSearchSchema
.
This method will be invoked only if the SetSchemaRequest
is setting a lower
version number than the current AppSearchSchema
saved in AppSearch.
If this Migrator
is provided to cover a compatible schema change via AppSearchSession.setSchema(SetSchemaRequest, Executor, Executor, Consumer)
, documents under the old version won't be removed unless you use
the same document ID.
This method will be invoked on the background worker thread.
This method may take several seconds to complete, so it should
only be called from a worker thread.
Parameters | |
---|---|
currentVersion |
int : The current version of the document's schema. |
finalVersion |
int : The final version that documents need to be migrated to. |
document |
GenericDocument : The GenericDocument need to be translated to new version.
This value cannot be null . |
Returns | |
---|---|
GenericDocument |
A GenericDocument in new version.
This value cannot be null . |
onUpgrade
public abstract GenericDocument onUpgrade (int currentVersion, int finalVersion, GenericDocument document)
Migrates GenericDocument
to a newer version of AppSearchSchema
.
This method will be invoked only if the SetSchemaRequest
is setting a higher
version number than the current AppSearchSchema
saved in AppSearch.
If this Migrator
is provided to cover a compatible schema change via AppSearchSession.setSchema(SetSchemaRequest, Executor, Executor, Consumer)
, documents under the old version won't be removed unless you use
the same document ID.
This method will be invoked on the background worker thread provided via AppSearchSession.setSchema(SetSchemaRequest, Executor, Executor, Consumer)
.
This method may take several seconds to complete, so it should
only be called from a worker thread.
Parameters | |
---|---|
currentVersion |
int : The current version of the document's schema. |
finalVersion |
int : The final version that documents need to be migrated to. |
document |
GenericDocument : The GenericDocument need to be translated to new version.
This value cannot be null . |
Returns | |
---|---|
GenericDocument |
A GenericDocument in new version.
This value cannot be null . |
shouldMigrate
public abstract boolean shouldMigrate (int currentVersion, int finalVersion)
Returns true
if this migrator's source type needs to be migrated to update from
currentVersion to finalVersion.
Migration won't be triggered if currentVersion is equal to finalVersion even if shouldMigrate(int, int)
return true;
Parameters | |
---|---|
currentVersion |
int |
finalVersion |
int |
Returns | |
---|---|
boolean |