Inserting several simple objects into a table using MyBatis

Question

Say I have a table in a database like this:

CREATE TABLE entities( 
    id INT PRIMARY KEY AUTO_INCREMENT,
    friendly_name VARCHAR(100),
    data1 BLOB NOT NULL,
    data2 BLOB NOT NULL,
    loads of other fields
)
ENGINE INNODB;

And I have a MyBatis Mapper which I want to use to create an insert that only inserts friendly_name, data1 and data2, but none of the other fields.

I would like to create a method along these lines in the mapper:

public void addNewUnverifiedEntity(String friendlyName, byte[] data1, byte[] data2);

I have the following in my mapper xml:

<insert id="addNewUnverifiedEntity" useGeneratedKeys="true" keyProperty="id">
  insert into entities (friendly_name,data1,data2)
  values (#{friendlyName},#{data1},#{data2})
</insert>

But when I try to call the mapper method I get the following exception:

Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column 'data1' cannot be null
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
...

In the log output a little I also see this gem:

16:59:36.754 [main] DEBUG o.a.i.d.pooled.PooledDataSource - Created connection 1110623531.
16:59:36.764 [main] DEBUG java.sql.Connection - ooo Connection Opened
16:59:36.987 [main] DEBUG java.sql.PreparedStatement - ==>  Executing: insert into entities (friendly_name,verified_by,key_digest,key_data) values (?,?,?,?) 
16:59:36.987 [main] DEBUG java.sql.PreparedStatement - ==> Parameters: null, null, null, null

Data does not seem to actually go from the mapper to statement, and therefore the table. (I called the method with two non-empty byte arrays and a defined string)

I can see that I can create a POJO to only contain these fields but I would much rather go with the approach in my mapper.

How exactly do I go about making a method like addNewUnverifiedEntity work?

you could change your table definition to make the column 'key_data' nullable. — Andrew Fielden
– Andrew Fielden, Commented Feb 16, 2015 at 12:43
Crap, i made a boo boo in my exception report. It should have said "data1" :) The problem is that even though i put data in "data1" data does not get to the table, and the exception occurs. — Martin Nielsen
– Martin Nielsen, Commented Feb 16, 2015 at 13:06

Martin Nielsen · Accepted Answer · 2015-02-16 16:13:09Z

2

Answering my own question. It seems that when posting several parameters to a mybatis mapper, the parameters are named by their position and not their name, so #{1} #{2} #{3} in my case. In order to make the mapper xml work in my case (With meaningful names) the mapper methods parameters can be annotated with the @Param tag.

answered Feb 16, 2015 at 16:13

Martin Nielsen

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