import io.realm.FieldAttribute; //导入依赖的package包/类
/**
 * This test surfaces a bunch of problems, most of them seem to be around caching of the schema
 * during a transaction
 *
 * 1) Removing the primary key do not invalidate the cache in RealmSchema and those cached
 *    are ImmutableRealmObjectSchema so do not change when the primary key is removed.
 *
 * 2) Addding `schema.refresh()` to RealmObjectSchema.removePrimaryKey()` causes
 *    RealmPrimaryKeyConstraintException anyway. Unclear why.
 */
@Test
public void removingPrimaryKeyRemovesConstraint_typeSetters() {
    RealmConfiguration config = configFactory.createConfigurationBuilder()
            .name("removeConstraints").build();

    DynamicRealm realm = DynamicRealm.getInstance(config);
    RealmSchema realmSchema = realm.getSchema();
    realm.beginTransaction();
    RealmObjectSchema tableSchema = realmSchema.create("Employee")
            .addField("name", String.class, FieldAttribute.PRIMARY_KEY);

    realm.createObject("Employee", "Foo");
    DynamicRealmObject obj = realm.createObject("Employee", "Foo2");

    try {
        // Tries to create 2nd entry with name Foo.
        obj.setString("name", "Foo");
    } catch (IllegalArgumentException e) {
        tableSchema.removePrimaryKey();
        obj.setString("name", "Foo");
    } finally {
        realm.close();
    }
}
 

import io.realm.FieldAttribute; //导入依赖的package包/类
private static void changeFieldType(RealmObjectSchema objectSchema, String fieldName,
                             Class newType, @Nullable FieldAttribute attribute,
                             Action3<DynamicRealmObject, String, String> transformation) {
    String tempFieldName = fieldName + "_temp";
    if (attribute != null) {
        if (attribute == FieldAttribute.PRIMARY_KEY && objectSchema.hasPrimaryKey()) {
            // remove existing primary key
            objectSchema.removePrimaryKey();
        }
        objectSchema.addField(tempFieldName, newType, attribute);
    } else {
        objectSchema.addField(tempFieldName, newType);
    }
    objectSchema
            .transform(obj -> {
                transformation.call(obj, fieldName, tempFieldName);
            })
            .removeField(fieldName)
            .renameField(tempFieldName, fieldName);
}
 

import io.realm.FieldAttribute; //导入依赖的package包/类
@Override
public void migrate(DynamicRealm realm, long oldVersion, long newVersion) {
    if (newVersion > oldVersion) {
        RealmSchema realmSchema = realm.getSchema();
        if (oldVersion == 1) {
            realmSchema.create("UpgradeModel")
                    .addField("localId", String.class, FieldAttribute.PRIMARY_KEY)
                    .addField("version", String.class)
                    .addField("url", String.class)
                    .addField("compulsive_upgrade", String.class)
                    .addField("description", String.class);
        }
        updateLearningModel(realmSchema);
    }
}
 

import io.realm.FieldAttribute; //导入依赖的package包/类
@Override
public void migrate(@NonNull final DynamicRealm realm, long oldVersion, long newVersion) {
    Log.d(TAG, "Starting migration from " + oldVersion + " to " + newVersion);

    // Migration from versions < 9 not supported, versions prior 9 were missing the
    // contentHash for items
    if(oldVersion < 9) {
        throw new IllegalStateException("Migration from Schema < 9 not supported");
    }

    RealmSchema schema = realm.getSchema();

    /*
      9 -> 10

      - Add primary key ID to TemporaryFeed
      - Rename TemporaryFeed id to treeItemId
      - add TemporaryFeed object for list and pager activities
     */
    if(oldVersion == 9) {
        realm.delete("TemporaryFeed");

        final RealmObjectSchema temporaryFeedSchema = schema.get("TemporaryFeed");

        if(temporaryFeedSchema == null)
            throw new IllegalStateException("TemporaryFeed schema not found");

        temporaryFeedSchema
                .renameField(TemporaryFeed.ID, TemporaryFeed.TREE_ITEM_ID)
                .addField(TemporaryFeed.ID, long.class, FieldAttribute.PRIMARY_KEY);

        realm.createObject("TemporaryFeed", TemporaryFeed.LIST_ID);
        realm.createObject("TemporaryFeed", TemporaryFeed.PAGER_ID);

        oldVersion++;
    }

    /*
      10 -> 11

       - Make sure every item has updatedAt != null, set updatedAt = pubDate if not
     */
    if(oldVersion == 10) {
        for(DynamicRealmObject object: realm.where("Item").isNull(Item.UPDATED_AT).findAll()) {
            object.setDate(Item.UPDATED_AT, object.getDate(Item.PUB_DATE));
        }

        oldVersion++;
    }

    /*
      11 -> 12

      - Add active property to Item
     */
    if(oldVersion == 11) {
        final RealmObjectSchema itemSchema = schema.get("Item");

        if(itemSchema == null)
            throw new IllegalStateException("Item schema not found");

        itemSchema
                .addField(Item.ACTIVE, boolean.class, FieldAttribute.INDEXED);

        //noinspection UnusedAssignment
        oldVersion++;
    }
}