different default value between XMLStatementBuilder and MapperAnnotationBuilder

[bringyou]

Hi, I found some differences between XmlStatementBuilder and MapperAnnotationBuilder when they parse SQL statement, they will give some variables different values when user didn't set. Sometimes, it can cause different behaviors.
For example, here is some code from XMLStatementBuilder

void parseStatementNode() {
    // other codes are omitted
    String resultSetType = context.getStringAttribute("resultSetType");
    ResultSetType resultSetTypeEnum = resolveResultSetType(resultSetType);
    // omit some codes
    builderAssistant.addMappedStatement(id, sqlSource, statementType, sqlCommandType,
        fetchSize, timeout, parameterMap, parameterTypeClass, resultMap, resultTypeClass,
        resultSetTypeEnum, flushCache, useCache, resultOrdered, 
        keyGenerator, keyProperty, keyColumn, databaseId, langDriver, resultSets);
}   
// inherited from BaseBuilder
protected ResultSetType resolveResultSetType(String alias) {
    if (alias == null) {
      return null;
    }
    try {
      return ResultSetType.valueOf(alias);
    } catch (IllegalArgumentException e) {
      throw new BuilderException("Error resolving ResultSetType. Cause: " + e, e);
    }
  }

Here is some code from MapperAnnotationBuilder

 void parseStatement(Method method) {
// omits unrelated codes
   Options options = method.getAnnotation(Options.class);
   ResultSetType resultSetType = ResultSetType.FORWARD_ONLY;
   if (options != null) {
        resultSetType = options.resultSetType();
      }
}

So we can see, users get different resultSetType value when they didn't set, one is null and the other is ResultSetType.FORWARD_ONLY. This may cause some different behaviors when others' code depend on the value.

MyBatis version

3.4.6

[jiangrongbo]

the default ResultSetType depend on jdbc driver , most jdbc driver default ResultSetType is FORWARD_ONLY if not assigned . it's better to keep XMLStatementBuilder and MapperAnnotationBuilder has same default ResultSetType ;

[harawata]

Thank you @bringyou for the report and @rongbo-j for the comment.

The doc says "Default is unset (driver dependent).", so we may need to fix the annotation builder.

[kazuki43zoo]

About backward compatibility

XML based mapper

Keep backward compatibility.

Annotation based mapper

Fetching data is same. (= Keep backward compatibility)
However, If the resultSetType attribute is omitted using annotation driven mapper, internal processing of pagination may change. In version 3.4 or before, it apply FORWARD_ONLY(=move to offset position by loop). But since 3.5, it depends on JDBC driver default behavior.

[bringyou]

thank you guys