Kotlin-使用Persistence Room:runtime lib从Room数据库返回新插入的ID [英] Kotlin - return new inserted id from Room database using Persistence Room:runtime lib

问题描述

我正在尝试使用Kotlin在Room数据库中插入用户记录，并且运行良好.

I am trying to insert user record in Room database using Kotlin and It's working perfectly.

现在，我想返回新插入的记录ID，以检查是否已成功将记录插入到Room数据库中.

And now I want to return newly inserted record id to check if a record is successfully inserted or not in Room database.

但是当我在insert方法中应用Long返回类型并在那段时间运行代码时，出现以下错误.

But when I am applying Long return type in the insert method and run the code that time I get the following error.

错误:方法返回的时间很长，但是它应该返回以下值之一: void, long[], java.lang.Long[], java.util.List<java.lang.Long>.如果 您要返回查询中的行ID列表，请插入 方法只能接收1个参数.

error: Method returns long but it should return one of the following: void, long[], java.lang.Long[], java.util.List<java.lang.Long>. If you want to return the list of row ids from the query, your insertion method can receive only 1 parameter.

public abstract long insertUser(@org.jetbrains.annotations.NotNull()

我正在使用此库.

实现"android.arch.persistence.room:runtime:1.0.0"

implementation "android.arch.persistence.room:runtime:1.0.0"

kapt "android.arch.persistence.room:compiler:1.0.0"

这是我的插入查询.

@Insert
fun insertUser(vararg userRegistrationEntity: UserRegistrationEntity):Long;

这是我的addAsyncTask，我在其中将记录插入到Room数据库中

Here is my addAsyncTask where I am inserting a record in Room database

private fun userRegistration(userRegistrationEntity: UserRegistrationEntity) {
        addAsyncTask(appDatabase!!).execute(userRegistrationEntity) 
    }

    private class addAsyncTask constructor(private val appDatabase: AppDatabase) : AsyncTask<UserRegistrationEntity, Void, Long>() {
        override fun doInBackground(vararg params: UserRegistrationEntity): Long? {
           // val a = appDatabase.userRegistrationDao().addUser(params[0]);
            val newReturnId = appDatabase.userRegistrationDao().insertUser(params[0]);
            return newReturnId
        }

        override fun onPostExecute(result: Long?) {
            super.onPostExecute(result)
            Log.d("value", result.toString()) 
        }
    }

推荐答案

如果要插入多个实体，则只能以数组或列表的形式获取它们的ID，例如:

If you're inserting multiple entities, you can only get their IDs back in an array or list, for example, like this:

@Insert
fun insertUsers(vararg userRegistrationEntities: UserRegistrationEntity): List<Long>

如果一次插入一个实体，则可以以Long的形式获取其ID:

If you insert one entity at a time, you can get its ID back as a Long:

@Insert
fun insertUser(userRegistrationEntity: UserRegistrationEntity): Long

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