ResultType

ResultType is a configuration concept used in the MyBatis data mapper framework to declare the Java type that a SQL query result should be mapped to. It identifies the target type for the result or for each row returned by the statement.

In XML configuration, resultType is specified on a statement element such as select, update, or insert. For example, a simple select might declare resultType="com.example.User", indicating that each row in the result set should be mapped to an instance of that class. The value can be a fully qualified class name or a type alias defined in the configuration. When using a primitive or wrapper type like Integer or String, the statement is expected to return a single column whose value is mapped to that type. If multiple columns are returned, mapping to a complex object relies on property names matching column labels (with optional underscore-to-camel-case conversion).

In annotation-based mappers, a similar effect can be achieved with the @ResultType annotation (often used in conjunction with @Select), to specify the target return type for a method without writing a separate resultMap. For more complex mappings, or when column-to-property mismatches are significant, developers typically use a resultMap instead of resultType, as resultMap provides explicit control over each column-to-property mapping and can handle nested associations.

When to use resultType: for straightforward mappings to POJOs or single-column results where automatic column-name mapping is sufficient. When results are more complex, or require custom transformations, a resultMap is preferred. In addition, resultType can also be used with Map<String, Object> to obtain raw row data.