4.5 Builder API

The Builder API uses LambdaTemplate to describe INSERT, UPDATE, DELETE, QUERY and other operations through chained methods. The matching dialect generates SQL or target commands for execution through a JDBC driver. This is one application adapter entry point for shared access patterns across data sources.

For example, the same condition builder pattern can produce SQL through a relational dialect, document commands through the MongoDB dialect, or Query DSL through an Elasticsearch dialect. Supported operations and conditions are listed in the builder capabilities by data source.

Best For

• You want to reduce handwritten SQL or data source-specific commands.
• Query conditions have many combinations and you don't want to manually concatenate WHERE clauses.
• You want the same API to adapt across different database dialects.
• You need to express more complex conditions beyond BaseMapper's pre-built CRUD.

Not Best For

• SQL or DSL is already fixed and complex enough that maintaining the commands directly is clearer.
• You need lots of database-specific syntax, window functions, or complex JOINs.
• You want SQL/DSL fully maintained by DBAs or in standalone XML files.

For those scenarios, use JdbcTemplate or File Mapper.

Three Modes

Mode	Requires object mapping	Best for
Entity mode	Yes	Entity classes exist; use method references like User::getName to reference columns.
Map mode	Yes	Table mapping exists, but the data carrier is Map.
Freedom mode	No	No entity mapping; directly uses table names and string column names.

Minimal Example

With DataSource

DataSource dataSource = ...;
LambdaTemplate lambda = new LambdaTemplate(dataSource);

List<User> users = lambda.query(User.class)
        .eq(User::getStatus, "ACTIVE")
        .ge(User::getAge, 18)
        .queryForList();

With Connection

Connection conn = ...;
LambdaTemplate lambda = new LambdaTemplate(conn);

List<User> users = lambda.query(User.class)
        .eq(User::getStatus, "ACTIVE")
        .ge(User::getAge, 18)
        .queryForList();

Freedom mode

Map<String, Object> row = lambda.queryFreedom("users")
        .eq("id", 1)
        .queryForObject();

Learn More

• LambdaTemplate: complete guide to the Builder API.
• Condition Builder: WHERE condition construction capabilities.
• Object Mapping: table and column mapping that Entity mode depends on.