帶有 MySQL 的 Spring Boot R2DBC - 異常：找不到表

Question

我對String Boot和后端開發（可能三天或更短）非常陌生，我希望構建REST API以從不同的客戶端使用。

所以我從一個簡單的演示應用程序開始，它有一個名為/register的端點。 我們發布一個帶有username和password的JSON字符串以創建一個新用戶（如果不存在）。

我在HSQLDB中使用了JPA ，它在內存上的持久化工作得很好。 但是最近我想使用RxJava因為我在 Android 上很熟悉，所以我切換到R2DBC with MySQL 。

MySQL服務器在端口3306上運行良好，應用程序在localhost:8080上使用 PostMan 進行了測試

當我嘗試查詢用戶表或插入實體時出現問題，它看起來像這樣：

{
    "timestamp": "2020-03-22T11:54:43.466+0000",
    "status": 500,
    "error": "Internal Server Error",
    "message": "execute; bad SQL grammar [UPDATE user_entity SET username = $1, password = $2 WHERE user_entity.id = $3]; nested exception is io.r2dbc.spi.R2dbcBadGrammarException: [42102] [42S02] Table \"USER_ENTITY\" not found; SQL statement:\nUPDATE user_entity SET username = $1, password = $2 WHERE user_entity.id = $3 [42102-200]",
    "path": "/register"
}

這是異常的完整日志文件。

我一直在尋找解決方案幾個小時，但似乎在任何地方都找不到，所以我希望我能在這里找到它。

讓我們分解項目，以便更容易找到解決方案：

1. 數據庫：

2. application.properties:

logging.level.org.springframework.data.r2dbc=DEBUG
spring.datasource.url=jdbc:mysql://localhost:3306/demodb
spring.datasource.username=root
spring.datasource.password=root

3. 數據庫配置：

@Configuration
@EnableR2dbcRepositories
class DatabaseConfiguration : AbstractR2dbcConfiguration() {

    override fun connectionFactory(): ConnectionFactory
         = ConnectionFactories.get(
                builder().option(DRIVER, "mysql")
                    .option(HOST, "localhost")
                    .option(USER, "root")
                    .option(PASSWORD, "root") 
                    .option(DATABASE, "demodb")
                    .build()
        )


}

4.注冊控制器：

@RequestMapping("/register")
@RestController
class RegistrationController @Autowired constructor(private val userService: UserService) {

    @PostMapping
    fun login(@RequestBody registrationRequest: RegistrationRequest): Single<ResponseEntity<String>>
        = userService.userExists(registrationRequest.username)
            .flatMap { exists -> handleUserExistance(exists, registrationRequest) }
    
    private fun handleUserExistance(exists: Boolean, registrationRequest: RegistrationRequest): Single<ResponseEntity<String>> 
        = if (exists) Single.just(ResponseEntity("Username already exists. Please try an other one", HttpStatus.CONFLICT))
            else userService.insert(User(registrationRequest.username, registrationRequest.password)).map { user ->
                ResponseEntity("User was successfully created with the id: ${user.id}", HttpStatus.CREATED)
            }
    
}

5.用戶服務：

@Service
class UserService @Autowired constructor(override val repository: IRxUserRepository) : RxSimpleService<User, UserEntity>(repository) {

    override val converter: EntityConverter<User, UserEntity> = UserEntity.Converter

    fun userExists(username: String): Single<Boolean>
        = repository.existsByUsername(username)

}

6. RxSimpleService：

abstract class RxSimpleService<T, E>(protected open val repository: RxJava2CrudRepository<E, Long>)  {

    protected abstract val converter: EntityConverter<T, E>

    open fun insert(model: T): Single<T>
        = repository.save(converter.fromModel(model))
            .map(converter::toModel)

    open fun get(id: Long): Maybe<T>
        = repository.findById(id)
            .map(converter::toModel)

    open fun getAll(): Single<ArrayList<T>>
        = repository.findAll()
            .toList()
            .map(converter::toModels)

    open fun delete(model: T): Completable
        = repository.delete(converter.fromModel(model))

}

7. RxUserRepository：

@Repository
interface IRxUserRepository : RxJava2CrudRepository<UserEntity, Long> {

    @Query("SELECT CASE WHEN EXISTS ( SELECT * FROM ${UserEntity.TABLE_NAME} WHERE username = :username) THEN CAST(1 AS BIT) ELSE CAST(0 AS BIT) END")
    fun existsByUsername(username: String): Single<Boolean>

}

8. 最后，這是我的 UserEntity

@Table(TABLE_NAME)
data class UserEntity(
        @Id
        val id: Long,
        val username: String,
        val password: String
)  {

        companion object {
            const val TABLE_NAME = "user_entity"
        }

        object Converter : EntityConverter<User, UserEntity> {

            override fun fromModel(model: User): UserEntity
                   = with(model) { UserEntity(id, username, password) }

            override fun toModel(entity: UserEntity): User
                   = with(entity) { User(id, username, password) }

        }
}

User和RegistrationRequest只是帶有用戶名和密碼的簡單對象。 我錯過了什么？ 如果您需要更多代碼，請發表評論。

Answer 1

我終於設法解決了這個錯誤！

對於初學者來說，問題是如此簡單但又如此狡猾：

1. 我在 URL 中使用JDBC而不是R2DBC
2. 我正在使用H2運行時實現，所以它期待一個H2內存數據庫
3. 我的ConnectionFactory不是很正確

所以我所做的是以下內容：

1. 更新了我的build.gradle ：
   • 添加： implementation("io.r2dbc:r2dbc-pool") ， implementation("dev.miku:r2dbc-mysql:0.8.1.RELEASE")和runtimeOnly("mysql:mysql-connector-java")
   • 刪除： runtimeOnly("io.r2dbc:r2dbc-h2")

現在看起來像這樣：

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

plugins {
    id("org.springframework.boot") version "2.2.5.RELEASE"
    id("io.spring.dependency-management") version "1.0.9.RELEASE"
    kotlin("jvm") version "1.3.61"
    kotlin("plugin.spring") version "1.3.61"
}

group = "com.tamimattafi.backend"
version = "0.0.1-SNAPSHOT"
java.sourceCompatibility = JavaVersion.VERSION_11

repositories {
    mavenCentral()
    maven(url = "https://repo.spring.io/milestone")
}

dependencies {
    //SPRING BOOT
    implementation("org.springframework.boot:spring-boot-starter-security")
    implementation("org.springframework.boot:spring-boot-starter-web")
    implementation("org.springframework.boot.experimental:spring-boot-starter-data-r2dbc")

    //KOTLIN
    implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
    implementation("org.jetbrains.kotlin:kotlin-reflect")
    implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")

    //RX JAVA
    implementation("io.reactivex.rxjava2:rxjava:2.2.0")
    implementation("io.reactivex:rxjava-reactive-streams:1.2.1")

    //MYSQL
    implementation("dev.miku:r2dbc-mysql:0.8.1.RELEASE")
    implementation("io.r2dbc:r2dbc-pool")
    runtimeOnly("mysql:mysql-connector-java")

    //TEST
    testImplementation("org.springframework.boot:spring-boot-starter-test") {
        exclude(group = "org.junit.vintage", module = "junit-vintage-engine")
    }
    testImplementation("org.springframework.security:spring-security-test")
    testImplementation("io.projectreactor:reactor-test")
    testImplementation("org.springframework.boot.experimental:spring-boot-test-autoconfigure-r2dbc")
}

dependencyManagement {
    imports {
        mavenBom("org.springframework.boot.experimental:spring-boot-bom-r2dbc:0.1.0.M3")
    }
}

tasks.withType<Test> {
    useJUnitPlatform()
}

tasks.withType<KotlinCompile> {
    kotlinOptions {
        freeCompilerArgs = listOf("-Xjsr305=strict")
        jvmTarget = "1.8"
    }
}

2. 將我的application.properties更新為：

    spring.r2dbc.url=r2dbc:pool:mysql://127.0.0.1:3306/demodb spring.r2dbc.username=root spring.r2dbc.password=root

3. 將我的DatabaseConfiguration更新為此（請注意，我刪除了@EnableR2dbcRepositories因為它應該在其他地方）：

    @Configuration class DatabaseConfiguration : AbstractR2dbcConfiguration() { override fun connectionFactory(): ConnectionFactory = MySqlConnectionFactory.from( MySqlConnectionConfiguration.builder() .host("127.0.0.1") .username("root") .port(3306) .password("root") .database("demodb") .connectTimeout(Duration.ofSeconds(3)) .useServerPrepareStatement() .build() ) }

4. 更新了我的Application類（我在這里帶了注釋）：

    @SpringBootApplication @EnableR2dbcRepositories class DemoApplication fun main(args: Array<String>) { runApplication<DemoApplication>(*args) }

現在可以使用了！ 我希望有人會發現這有幫助，快樂編碼！

Answer 2

在application.properties您需要設置spring.jpa.hibernate.ddl-auto屬性。

選項是：

validate: validate the schema, makes no changes to the database.
update: update the schema.
create: creates the schema, destroying previous data.
create-drop: drop the schema when the SessionFactory is closed explicitly, typically when the application is stopped.
none: does nothing with the schema, makes no changes to the database