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问题描述

我有一个可以针对SQL Server或Oracle后端运行的Grails应用程序。我使用GORM作为ORM。



我想以支持两种数据库类型的方式映射大型文本字段。在我的Grails领域类中,我有类似的东西:

  class Note {
字符串内容

static constraint = {
content nullable:false,blank:false
}
}

然后我声明如下的数据库表:

   -  oracle 
CREATE TABLE NOTE

id NUMBER(19,0)NOT NULL,
version NUMBER(19,0)NOT NULL,
content CLOB NOT NULL
);

- SQL Server
CREATE TABLE NOTE

id NUMERIC(19,0)NOT NULL,
version NUMERIC(19,0)NOT NULL,
content NVARCHAR(MAX)NOT NULL
);

GORM在启动时运行于 validate 模式,而且我无法找到Oracle和SQL Server数据类型和GORM映射的组合,这些映射允许没有GORM的存储或大型文本字段无法正确启动。



I已尝试:


  • 在<$ c中将类型设置为 text $ c>映射,但这似乎不起作用。 Oracle抱怨期望 content 字段的类型为 long ,并且SQL Server需要一种<$ c $在这些情况下,你可以使用

  • code> clob ,它通过模式验证,但不允许我将字段设置为字符串值--GORM期望类型为 CLOB

    我应该如何配置我的数据库定义和GORM才能使其工作?

    解决方案

    最终出现了一种解决方案:通过在启动时查询Grails配置,您可以选择适当的数据类型。

      class Note {

    字符串内容

    静态约束= {
    content nullable:false,blank:false
    }

    static mappings = {
    content sqlType:DbSupport.bigStringType
    }
    }

    class DbSupport {

    static def getBigStringType(){

    //检查选择哪个hibernate方言,并选择
    / /该数据库类型的适当类型映射:
    def dialect = ApplicationHolder.application.config.dataSource.dialect
    switch(dialect){

    caseorg.hibernate.dialect .SQLServerDialect:
    returnnvarchar
    break

    caseorg.hibernate.dialect.O racle10gDialect:
    returnclob
    break
    }

    }
    }


    I have a Grails application that will run against either a SQL Server or Oracle backend. I am using GORM as an ORM.

    I want to map a large text field in a way that supports both database types. In my Grails domain class I have something like:

    class Note {
        String content
    
        static constraints = {
            content nullable: false, blank: false
        }
    }
    

    I then declare database tables that look like this:

    -- oracle
    CREATE TABLE NOTE 
    (
        id NUMBER(19, 0) NOT NULL,
        version NUMBER(19, 0) NOT NULL,
        content CLOB NOT NULL
    );
    
    -- SQL Server
    CREATE TABLE NOTE 
    (
        id NUMERIC(19, 0) NOT NULL,
        version NUMERIC(19, 0) NOT NULL,
        content NVARCHAR(MAX) NOT NULL
    );
    

    GORM is running in validate mode on startup, and I can't find a combination of Oracle and SQL Server data types and GORM mappings that allow the storage or large text fields without GORM failing to start correctly.

    I have tried:

    • setting the type to text in mappings, but this doesn't seem to work. Oracle complains about expecting the content field to be of type long, and SQL Server wants a type of text in these circumstances.

    • setting the type to clob, which passes schema validation but then doesn't allow me to set the field as a string value - GORM expects data of type CLOB.

    How should I configure my database definitions and GORM to make this work?

    解决方案

    As hackish as it is, a solution eventually emerged: by querying the Grails configuration at startup time, you can select an appropriate data type.

    class Note {
    
        String content
    
        static constraints = {
            content nullable: false, blank: false
        }
    
        static mappings = {
            content sqlType: DbSupport.bigStringType
        }
    }
    
    class DbSupport {
    
        static def getBigStringType() {
    
            // examine which hibernate dialect is selected, and pick
            // an appropriate type mapping for that database type:
            def dialect = ApplicationHolder.application.config.dataSource.dialect
            switch (dialect) {
    
                case "org.hibernate.dialect.SQLServerDialect":
                    return "nvarchar"
                    break
    
                case "org.hibernate.dialect.Oracle10gDialect":
                    return "clob"
                    break
            }
    
        }
    }
    

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10-18 20:16