@Override
public long execute(Realm realm, long version) {
/*
// Version 0
class Person
String firstName;
String lastName;
int age;
// Version 1
class Person
String fullName; // combine firstName and lastName into single field
int age;
*/
// Migrate from version 0 to version 1
if (version == 0) {
Table personTable = realm.getTable(Person.class);
long fistNameIndex = getIndexForProperty(personTable, "firstName");
long lastNameIndex = getIndexForProperty(personTable, "lastName");
long fullNameIndex = personTable.addColumn(ColumnType.STRING, "fullName");
for (int i = 0; i < personTable.size(); i++) {
personTable.setString(
fullNameIndex,
i,
personTable.getString(fistNameIndex, i)
+ " "
+ personTable.getString(lastNameIndex, i));
}
personTable.removeColumn(getIndexForProperty(personTable, "firstName"));
personTable.removeColumn(getIndexForProperty(personTable, "lastName"));
version++;
}
/*
// Version 2
class Pet // add a new model class
String name;
String type;
class Person
String fullName;
int age;
RealmList<Pet> pets; // add an array property
*/
// Migrate from version 1 to version 2
if (version == 1) {
Table personTable = realm.getTable(Person.class);
Table petTable = realm.getTable(Pet.class);
long nameColumnIndex = petTable.addColumn(ColumnType.STRING, "name");
long typeColumnIndex = petTable.addColumn(ColumnType.STRING, "type");
long petsIndex = personTable.addColumnLink(ColumnType.LINK_LIST, "pets", petTable);
long fullNameIndex = getIndexForProperty(personTable, "fullName");
for (int i = 0; i < personTable.size(); i++) {
if (personTable.getString(fullNameIndex, i).equals("JP McDonald")) {
long rowIndex = petTable.addEmptyRow();
petTable.setString(nameColumnIndex, rowIndex, "Jimbo");
petTable.setString(typeColumnIndex, rowIndex, "dog");
personTable.getUncheckedRow(i).getLinkList(petsIndex).add(rowIndex);
}
}
version++;
}
/*
// Version 3
class Pet
String name;
int type; // type becomes int
class Person
String fullName;
RealmList<Pet> pets; // age and pets re-ordered
int age;
*/
// Migrate from version 2 to version 3
if (version == 2) {
Table petTable = realm.getTable(Pet.class);
long oldTypeIndex = getIndexForProperty(petTable, "type");
long typeIndex = petTable.addColumn(ColumnType.INTEGER, "type");
for (int i = 0; i < petTable.size(); i++) {
String type = petTable.getString(oldTypeIndex, i);
if (type.equals("dog")) {
petTable.setLong(typeIndex, i, 1);
} else if (type.equals("cat")) {
petTable.setLong(typeIndex, i, 2);
} else if (type.equals("hamster")) {
petTable.setLong(typeIndex, i, 3);
}
}
petTable.removeColumn(oldTypeIndex);
version++;
}
return version;
}
