Android 房间 Kotlin 抛出删除查询错误

Question

我正在尝试使用 Android Room 2.3.0，我目前收到以下编译错误：

项目：

error: Not sure how to handle query method's return type (java.lang.Object). DELETE query methods must either return void or int (the number of deleted rows).
    public abstract java.lang.Object deleteAllProjects(@org.jetbrains.annotations.NotNull()
error: Query method parameters should either be a type that can be converted into a database column or a List / Array that contains such type. You can consider adding a Type Adapter for this.
    kotlin.coroutines.Continuation<? super kotlin.Unit> continuation);
error: Unused parameter: continuation
    public abstract java.lang.Object deleteAllProjects(@org.jetbrains.annotations.NotNull()
error: Type of the parameter must be a class annotated with @Entity or a collection/array of it.
    kotlin.coroutines.Continuation<? super java.lang.Long> continuation);
error: Not sure how to handle insert method's return type.
    public abstract java.lang.Object insertProject(@org.jetbrains.annotations.NotNull()
error: Not sure how to handle delete method's return type. Currently the supported return types are void, int or Int.
    public abstract java.lang.Object deleteProject(@org.jetbrains.annotations.NotNull()
error: Type of the parameter must be a class annotated with @Entity or a collection/array of it.
    kotlin.coroutines.Continuation<? super kotlin.Unit> continuation);

反道：

Execution failed for task ':app:kaptDebugKotlin'.
> A failure occurred while executing org.jetbrains.kotlin.gradle.internal.KaptWithoutKotlincTask$KaptExecutionWorkAction
   > java.lang.reflect.InvocationTargetException (no error message)

但是，我的 ProjectDao.kt 文件具有以下内容：

@Dao
interface ProjectDao {
    @Query("SELECT * FROM table_projects")
    fun getAll(): List<Project>

    @Insert
    suspend fun insertProject(project: Project): Long

    @Insert
    fun insertProjects(projects: List<Project>)

    @Delete
    suspend fun deleteProject(project: Project)

    @Query("DELETE FROM table_projects")
    suspend fun deleteAllProjects()

    @Transaction
    @Query("SELECT * FROM table_projects")
    fun getAllProjectsWithCounters(): List<ProjectWithCounters>

    @Transaction
    @Query("SELECT * FROM table_projects WHERE id_project=:projectID")
    fun getProjectWithCounters(projectID: Long): ProjectWithCounters
}

我以前没有遇到过任何问题，突然间我收到了这些错误，我不知道是什么原因造成的。

谢谢！

Answer 1

我解决了这个问题如下

我将 Kotlin 版本设置为1.6.10而不是 Room 设置为2.4.2

Answer 2

使用@Delete注释，您必须定义一个返回数据类型：

DELETE 查询方法必须返回 void 或 int（删除的行数）。

所以这应该是：

@Delete
suspend fun deleteProject(project: Project): Integer

成功时返回1 ，数据库中不存在project时返回0 。

Answer 3

设置 kotlin 版本为 1.5.21 或 1.5.31 Kotlin 1.6.0 不能在 ROOM QUERY 中使用暂停。
classpath 'org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.21'

Answer 4

在 Dao 函数中使用协程时我遇到了同样的问题

对我来说只是改变

kapt "androidx.room:room-compiler:$room_version"

至

annotationProcessor "androidx.room:room-compiler:$room_version"

如果您使用List or MutableLiveData检查此答案