Values are replaces by default value when updating

[N3TC4T]

How frequently does the bug occur?

Always

Description

When you update a record and the schema includes default values, any properties that are not explicitly provided in the update will be replaced with their default values.

Note: This only happens after upgrading to v12

Schema

{
        name: 'MySchema',
        primaryKey: 'id',
        properties: {
            id: { type: 'int' },
            fieldOne: { type: 'string' },
            fieldTwo:  { type: 'string', default: 'DEFAULT_VALUE' },
        },
}

Creating the record

realm.create("MySchema", {id: 1337, fieldOne: "SOME_VALUE", fieldTwo: "NOT_DEFAULT_VALUE" })

Updating the record

realm.create("MySchema", {id: 1337, fieldOne: "SOME_OTHER_VALUE" },  Realm.UpdateMode.All)

This will cause the value of the fieldTwo``{{ field to be updated to }}``DEFAULT_VALUE, even though we didn't explicitly specify this property when performing the update.

from docs:

declare enum UpdateMode {
    /**
     * Objects are only created. If an existing object exists, an exception is thrown.
     */
    Never = "never",
    /**
     * If an existing object exists, only properties where the value has actually
     * changed will be updated. This improves notifications and server side
     * performance but also have implications for how changes across devices are
     * merged. For most use cases, the behavior will match the intuitive behavior
     * of how changes should be merged, but if updating an entire object is
     * considered an atomic operation, this mode should not be used.
     */
    Modified = "modified",
    /**
+     * If an existing object is found, all properties provided will be updated,
+     * any other properties will remain unchanged.     <==========
     */
    All = "all"
}

Expected behaviour

Default values should be used only when the property is missing, and this should happen exclusively when you're creating a new record that doesn't already exist.

Version

12.1.0

What services are you using?

Local Database only

Are you using encryption?

Yes

Platform OS and version(s)

iOS 16.4

[kneth]

@N3TC4T Thank you for reporting. For your details, I believe we can easily write a test to reproduce the bug. Out of curiosity (before writing the test), do you observe the same if you use Modified as mode?

[N3TC4T]

Thanks @kneth, Yes that was the first thing I tried and It's the same problem with Realm.UpdateMode.Modified

[kneth]

@N3TC4T We have a fix in #6132, and we hope to do a release early next week.

[sync-by-unito]

➤ kneth commented:

Released in v12.2.0