mysql - 将 Grails Gorm 连接到预先存在的 MySQL 数据库

Question

我正在尝试连接到现有表并在我的应用程序中使用它。 但是，当我尝试在我的 Controller 中访问我的信息时，它返回 null。

代码:

build.gradle(相关部分)

dependencies {
    classpath "org.grails:grails-gradle-plugin:$grailsVersion"
    classpath "org.grails.plugins:hibernate5:${gormVersion-".RELEASE"}"
    classpath "org.grails.plugins:views-gradle:1.1.6"
}

apply plugin:"org.grails.grails-web"
apply plugin:"org.grails.plugins.views-json"

dependencies {
    compile "org.grails.plugins:hibernate5:6.1.9"
    compile "org.hibernate:hibernate-ehcache"
    runtime 'mysql:mysql-connector-java:5.1.40' 
} 

application.yml(相关部分)

hibernate:
    cache:
        queries: false
        use_second_level_cache: false
        use_query_cache: false
        region.factory_class: org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory

dataSource:
    pooled: true
    jmxExport: true
    driverClassName: com.mysql.jdbc.Driver
    dialect: org.hibernate.dialect.MySQL5InnoDBDialect
    username: abc
    password: ''

environments:
    development:
        dataSource:
            dbCreate: create-drop
            url: jdbc:mysql://localhost:3306/moocs?useSSL=false
    test:
        dataSource:
            dbCreate: update
            url: jdbc:mysql://localhost:3306/moocs?useSSL=false
    production:
        dataSource:
            dbCreate: none
            url: jdbc:mysql://localhost:3306/moocs?useSSL=false
            properties:
                jmxEnabled: true
                initialSize: 5
                maxActive: 50
                minIdle: 5
                maxIdle: 25
                maxWait: 10000
                maxAge: 600000
                timeBetweenEvictionRunsMillis: 5000
                minEvictableIdleTimeMillis: 60000
                validationQuery: SELECT 1
                validationQueryTimeout: 3
                validationInterval: 15000
                testOnBorrow: true
                testWhileIdle: true
                testOnReturn: false
                jdbcInterceptors: ConnectionState
                defaultTransactionIsolation: 2 # TRANSACTION_READ_COMMITTED

型号

class MoocModel {
    String title
    String institution
    String url
    Boolean free
    String platform
}

数据库表

+--------------------+--------------+------+-----+---------+----------------+
| Field              | Type         | Null | Key | Default | Extra          |
+--------------------+--------------+------+-----+---------+----------------+
| primary_key_column | bigint(20)   | NO   | PRI | NULL    | auto_increment |
| free               | bit(1)       | NO   |     | NULL    |                |
| title              | varchar(255) | NO   |     | NULL    |                |
| url                | varchar(255) | NO   |     | NULL    |                |
| platform           | varchar(255) | NO   |     | NULL    |                |
| institution        | varchar(255) | NO   |     | NULL    |                |
+--------------------+--------------+------+-----+---------+----------------+

Controller

import MoocModel

import grails.rest.*
import grails.converters.*

class TableController {
    static responseFormats = ['json', 'xml']

    def index() { 
        def mm = MoocModel
        render mm.get(5) as JSON  // want to display entry with id == 5 
    }
}

我得到一个空数组，println mm.get(5) 返回 null 所以我认为没有与数据库建立连接。

Answer 1

您需要将您的字段映射到数据库列。默认情况下，grails 使用“id”列作为主键。 所以尝试添加到 MoocModel 中:

static mapping = {
    id name: 'primary_key_column'
}