如何使用MyBatis迭代对象的所有字段？

Question

I want to insert all fields of a object to a row, but I don't know the exact filed names. Does MyBatis support this?

Answer 1

Mybatis uses OGNL in places where expression is expected including collection attribute of the foreach .

OGNL allows to invoke static methods so you can leverage this.

With default scripting engine (assuming that properties names match column names) you can do something like this to generate the list of fields:

<bind name="objectProperties"
  value="@org.apache.commons.beanutils.BeanUtils@describe(myParameter).entrySet()" />

INSERT INTO mytable (
  <foreach index="propertyName" item="propertyValue"
    collection="objectProperties" separator=",">
        ${propertyName}
  </foreach>
)
VALUES (
  <foreach index="propertyName" item="propertyValue"
    collection="objectProperties" separator=",">
        @{propertyValue}
  </foreach>
)

Note that this was not tested and is here just to demonstrate the idea how you can approach this.

I personally haven't used foreach as I prefer to use velocity scripting engine . With velocity scripting engine this can definitely be done:

#set( $objectProperties = $BeanUtils.describe($myParameter) )

INSERT INTO mytable (
  #foreach($property in $objectProperties)
    ${property.key}
  #end
)
VALUES (
  #foreach($property in $objectProperties)
    @{property.value}
  #end
)

You would also need to add reference to commons BeanUtils class to velocity context by adding this configuration to mybatis-velocity.properties :

additional.context.attributes=BeanUtils:org.apache.commons.beanutils.BeanUtils

Answer 2

我认为您应该使用SQL语句select into来完成此要求。

Answer 3

your pojo s properties should be consistent with the table s columns, and the autoMapping should be true. maybe you have to give some codes of your project,So I'll give you more advice