How to elegantly obtain entity class variable names to build database query conditions?

Dynamically building query conditions is a common requirement when using MyBatis-Plus or other ORM frameworks for database operations. Writing query conditions directly using attribute name strings (such as "isDeleted") is not only redundant in code, but also difficult to maintain. This article discusses the elegant acquisition of entity class variable names in Java, simplifying code and improving maintainability, and provides solutions under the frameworks of MyBatis-Plus and tk.mybatis.

Problem: Under the tk.mybatis framework, using Example objects to build query conditions requires hard-coded attribute names, for example:

 Example example = new Example(Dog.class);
Example.Criteria criteria = example.createCriteria();
criteria.andEqualTo("isDeleted", deleteFlagenum.undelete.getCode());

Developers hope to get variable names directly like dog.isDeleted , avoiding hard-coded and large number of constant definitions.

tk.mybatis solution (using reflection, but with lower performance):

tk.mybatis itself does not directly support getting field names. Although reflection mechanisms can be used to achieve access methods similar to dog.isDeleted , this reduces performance and increases code complexity. Therefore, this method is not recommended.

MyBatis-Plus Solution (recommended):

MyBatis-Plus' LambdaQueryChainWrapper allows the use of Lambda expressions to dynamically build query conditions, avoiding hard-coded property names. The code is simpler, safer and easier to maintain:

 // Chain query, Lambda expression method LambdaQueryChainWrapper<dog> lambdaQuery = new LambdaQueryChainWrapper(dogMapper);

// Example:
List<dog> dogs = lambdaQuery.eq(Dog::getIsDeleted, deleteFlagenum.undelete.getCode()).list();</dog></dog>

MyBatis-Plus automatically parses the attribute name "isDeleted" in Dog::getIsDeleted to build the correct query conditions. This approach significantly improves code readability and maintainability.

Summarize:

For the requirement of dynamically building database query conditions, it is highly recommended to use MyBatis-Plus' LambdaQueryChainWrapper . It elegantly solves the problem of hard-coded attribute names through Lambda expressions, providing a simpler, efficient and easy-to-maintain solution. Although reflection can achieve similar functionality, performance and code readability are not as good as MyBatis-Plus' Lambda expressions.

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