hibernate - Grails GORM映射尝试访问不存在的字段 “class”

Question

这很奇怪。

class Service implements Serializable{

Integer id
String serviceName
String description
SortedSet serviceRequirements

static hasMany = [ serviceRequirements : ServiceRequirement]

static mapping = 
{
    table 'service'

    columns {
        id column:'serviceId'

    }
}}

访问serviceInstance.serviceRequirements时生成的休眠sql为:

  servicereq0_.serviceId as serviceId1_,
    servicereq0_.serviceRequirementId as serviceR1_1_,
    servicereq0_.serviceRequirementId as serviceR1_9_0_,
    servicereq0_.version as version9_0_,
    servicereq0_.description as descript3_9_0_,
    servicereq0_.header as header9_0_,
    servicereq0_.isPersonal as isPersonal9_0_,
    servicereq0_.requirementKey as requirem6_9_0_,
    servicereq0_.required as required9_0_,
    servicereq0_.serviceId as serviceId9_0_,
    servicereq0_.type as type9_0_,
    servicereq0_.weight as weight9_0_,
    servicereq0_.oauthAccessTokenUrl as oauthAc12_9_0_,
    servicereq0_.oauthAuthorizeAdditionalParameters as oauthAu13_9_0_,
    servicereq0_.oauthAuthorizeState as oauthAu14_9_0_,
    servicereq0_.oauthAuthorizeUrl as oauthAu15_9_0_,
    servicereq0_.oauthClientId as oauthCl16_9_0_,
    servicereq0_.oauthClientSecret as oauthCl17_9_0_,
    servicereq0_.oauthRequestTokenUrl as oauthRe18_9_0_,
    servicereq0_.oauthType as oauthType9_0_,
    servicereq0_.class as class9_0_ 

除了最后一个“类”，所有字段都可以。它在数据库或称为ServiceRequirement的域类中根本不存在。

Answer 1

当列class存储多个类时，该列会自动添加到表中。如果ServiceRequirement类具有也是域类的子类，则该表将需要class列来知道它是哪种ServiceRequirement。如果设置了dbCreate，Grails通常很聪明，可以自动添加该列，但是如果您手动管理模式，则需要自己添加。