IssueTracker

@NonNull constraint is already supported: if you added @NonNull from support library when your column will have NonNull constraint.

One idea for supporting DEFAULT is to add a new option to @ColumnInfo.

@Entity
data class Sample(
    @PrimaryKey
    val id: Long,
    @ColumnInfo(defaultValue = "'hello'")
    val message: String
)

This does not work because this class needs to be created with a concrete value to the `message` field, and the value specified in the annotation is never used.
I can't really think of a good way to solve this.


https://www.sqlite.org/lang_createtable.html

SQLite supports 3 types of values for DEFAULT.
- Constant values. NULL, INTEGER, TEXT, etc.
- Expressions in parentheses. (random()), etc.
  This cannot reference other columns.
- Date time expressions. CURRENT_TIME, CURRENT_DATE, and CURRENT_TIMESTAMP.

All of these can be easily simulated by other means, such as Kotlin default arguments.
Are there any use cases where SQLite DEFAULT is absolutely necessary?

I think we can do it like this.

@Entity
data class User(
    @PrimaryKey
    val id: Long,
    val name: String,
    @ColumnInfo(defaultValue = "Hello")
    val message: String)

data class UserSummary(
    val id: Long,
    val name: String)

@Dao
interface Dao {
    @Insert(User::class)
    fun insert(val summary: UserSummary)
    @Update(User::class)
    fun update(val summary: UserSummary)
}

The POJO class has to have a field matching the primary key.
This way, we don't need to make the field nullable. What do you think?

I think they are 2 different things.
A part of this is allowing people to set default values on columns such that it will translate into sqlite. They may simply be relying on it for @Query methods that do insert (which we do not support yet but we can, we should).

Another task is allowing people to use @Insert / @Update to insert into tables that are different from the passed in pojo.
For that, we probably need to enforce the primary key set on the `UserSummary` but for `Insert` we can let them not have it as long as there is an autogenerate primary key.

I filed partial @Insert/@Update separately as b/127549506.

Project: platform/frameworks/support
Branch: androidx-master-dev

commit 4f917f20e63afc653a6092ad87cfbb10bcc1552c
Author: Yuichi Araki <yaraki@google.com>
Date:   Tue Nov 13 17:19:00 2018

    Support column default value
   
    Adds a new method @ColumnInfo#defaultValue() to allow declaring the
    schema default value of a column. The method allows for SQL literal
    values and expressions. Room will also interpret the default value as
    a string literal (surrounding it with single quotess) when the affinity
    of the column in TEXT.
   
    Bug: 64088772
    Test: FieldProcessorTest, DefaultValueTest
    Change-Id: I4219eaec34deae618c1b119287fd949a18315936

M       room/common/api/2.2.0-alpha01.ignore
M       room/common/api/2.2.0-alpha01.txt
M       room/common/api/current.txt
M       room/common/src/main/java/androidx/room/ColumnInfo.java
M       room/compiler/src/main/kotlin/androidx/room/processor/FieldProcessor.kt
M       room/compiler/src/main/kotlin/androidx/room/processor/ProcessorErrors.kt
M       room/compiler/src/main/kotlin/androidx/room/verifier/DatabaseVerifier.kt
M       room/compiler/src/main/kotlin/androidx/room/vo/Field.kt
M       room/compiler/src/main/kotlin/androidx/room/writer/TableInfoValidationWriter.kt
M       room/compiler/src/main/kotlin/androidx/room/writer/ValidationWriter.kt
M       room/compiler/src/test/data/databasewriter/output/ComplexDatabase.java
M       room/compiler/src/test/kotlin/androidx/room/processor/FieldProcessorTest.kt
M       room/compiler/src/test/kotlin/androidx/room/verifier/DatabaseVerifierTest.kt
M       room/integration-tests/incremental-annotation-processing/build.gradle
A       room/integration-tests/testapp/schemas/androidx.room.integration.testapp.migration.MigrationDb/9.json
M       room/integration-tests/testapp/src/androidTest/java/androidx/room/integration/testapp/migration/JournalDbPostMigrationTest.java
M       room/integration-tests/testapp/src/androidTest/java/androidx/room/integration/testapp/migration/MigrationDb.java
M       room/integration-tests/testapp/src/androidTest/java/androidx/room/integration/testapp/migration/MigrationTest.java
A       room/integration-tests/testapp/src/androidTest/java/androidx/room/integration/testapp/test/DefaultValueTest.java
M       room/migration/api/restricted_2.2.0-alpha01.txt
M       room/migration/api/restricted_current.txt
M       room/migration/src/main/java/androidx/room/migration/bundle/FieldBundle.java
M       room/migration/src/test/java/androidx/room/migration/bundle/DatabaseBundleTest.java
M       room/migration/src/test/java/androidx/room/migration/bundle/EntityBundleTest.java
M       room/migration/src/test/java/androidx/room/migration/bundle/FieldBundleTest.java
M       room/runtime/api/restricted_2.2.0-alpha01.txt
M       room/runtime/api/restricted_current.txt
M       room/runtime/src/androidTest/java/androidx/room/migration/TableInfoTest.java
M       room/runtime/src/main/java/androidx/room/util/TableInfo.java
M       room/testing/src/main/java/androidx/room/testing/MigrationTestHelper.java

https://android-review.googlesource.com/825803
https://goto.google.com/android-sha1/4f917f20e63afc653a6092ad87cfbb10bcc1552c

Project: platform/frameworks/support
Branch: androidx-master-dev

commit 9ad96403444f1f199af41946e6548c5cfc834ce1
Author: Daniel Santiago Rivera <danysantiago@google.com>
Date:   Wed Jun 26 13:55:46 2019

    Conditionally use column default value in equality check.
   
    Based on the constructor called, which can be used to distinguish
    between old generated code vs new generated code, don't take into
    consideration column default value in equality check. This makes it
    so that compatibility is maintained with old generated code using new
    runtime that haven't had the chance to migrate their unaccounted for
    default value migrations.
   
    Bug: 64088772
    Test: Manual - App with Room 2.1.0 & WM 1.0.0-alpha11, then upgarde both
          Room to 2.2.0-alpha01 and WM to 1.0.0. Forcing WM to run migration
          with new runtime, observed no crash.
   
    Change-Id: I6649c05d39dee2e7a03e46ff01310042ac2a61f2

M       room/runtime/src/androidTest/java/androidx/room/migration/TableInfoTest.java
M       room/runtime/src/main/java/androidx/room/util/TableInfo.java

https://android-review.googlesource.com/999815
https://goto.google.com/android-sha1/9ad96403444f1f199af41946e6548c5cfc834ce1

Project: platform/frameworks/support
Branch: androidx-master-dev

commit 23e7e21de3f2438aa6d8676c371f2db8bd444495
Author: Daniel Santiago Rivera <danysantiago@google.com>
Date:   Mon Jul 08 13:09:30 2019

    Conditionally use column default value in equality check part 2.
   
    Instead of using constructor to determine if default value should be
    ignored on equality check, simply ignore it if the table info has
    a null default value. In practice, this means don't validate database
    read default values (those read using PRAGMA table_info) if the
    generated code (and the entity class) does not define a default value.
   
    This eases migration to Room 2.2.0 for those apps who had accidentally
    added default values with migrations using 'ALTER TABLE x ADD COLUMN y
    TEXT NOT NULL DEFAULT z'. It won't cause their incremental migration
    test to suddenly start failing and it won't cause a runtime validation
    crash with 2.2.0 generated code for users whose database was migrated vs
    those who recently had a fresh install. Similarly for library users of
    Room such as WorkManager, their generated code using the old constructor
    will still create table info objects whose default value are null,
    causing them to not be validated because they weren't originally defined
    in the entity.
   
    There is also little to no value in prohibiting a default value in the
    schema that is not define in Room's entity. However, if a default value
    is defined in the entity class, then Room will validate its presence and
    content.
   
    Bug: 64088772
    Bug: 136019383
    Test: MigrationTest & TableInfoTest
    Change-Id: I1f3f34a2139b2505a2bf73b88f917252496df930

M       room/compiler/src/main/kotlin/androidx/room/writer/TableInfoValidationWriter.kt
M       room/compiler/src/test/data/databasewriter/output/ComplexDatabase.java
M       room/integration-tests/testapp/schemas/androidx.room.integration.testapp.migration.MigrationDb/10.json
A       room/integration-tests/testapp/schemas/androidx.room.integration.testapp.migration.MigrationDb/11.json
M       room/integration-tests/testapp/schemas/androidx.room.integration.testapp.migration.MigrationDb/9.json
M       room/integration-tests/testapp/src/androidTest/java/androidx/room/integration/testapp/migration/MigrationDb.java
M       room/integration-tests/testapp/src/androidTest/java/androidx/room/integration/testapp/migration/MigrationTest.java
M       room/runtime/api/restricted_2.2.0-alpha02.txt
M       room/runtime/api/restricted_current.txt
M       room/runtime/src/androidTest/java/androidx/room/migration/TableInfoTest.java
M       room/runtime/src/main/java/androidx/room/util/TableInfo.java
M       room/testing/src/main/java/androidx/room/testing/MigrationTestHelper.java

https://android-review.googlesource.com/1010368
https://goto.google.com/android-sha1/23e7e21de3f2438aa6d8676c371f2db8bd444495