Interface Dao<T>

public interface Dao<T>

Runtime contract a build-time-generated @Entity data access object implements. Application code rarely references Dao by name -- the typed dao is reached through EntityManager.dao(EntityClass.class).

All methods throw IOException for the same reasons com.codename1.db does: the underlying SQLite driver propagates IO failures, locking failures, and constraint violations through IOException.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    attach(Database db)
    Connects this dao to a Database instance.
    void
    createTable()
    CREATE TABLE IF NOT EXISTS ....
    void
    delete(T entity)
    DELETE ... WHERE id = ?.
    void
    dropTable()
    DROP TABLE IF EXISTS ....
    List<T>
    find(String where, Object... params)
    Free-form WHERE clause; where is appended verbatim after WHERE and params fills the ? placeholders.
    List<T>
    findAll()
    SELECT * FROM ....
    T
    findById(Object id)
    SELECT ... WHERE id = ?.
    void
    insert(T entity)
    INSERT INTO ....
    String
    tableName()
    The SQL table name.
    Class<T>
    type()
    The entity class this dao handles.
    void
    update(T entity)
    UPDATE ... WHERE id = ?.

  • Method Details

    • type

      Class<T> type()
      The entity class this dao handles.

    • tableName

      String tableName()
      The SQL table name. Defaults to the simple class name; an explicit @Entity(table="...") wins.

    • attach

      void attach(Database db)
      Connects this dao to a Database instance. Called by EntityManager.dao(Class); the same dao is reused for the lifetime of the entity manager.

    • createTable

      void createTable() throws java.io.IOException
      CREATE TABLE IF NOT EXISTS .... Idempotent.
      Throws:
      java.io.IOException

    • dropTable

      void dropTable() throws java.io.IOException
      DROP TABLE IF EXISTS ....
      Throws:
      java.io.IOException

    • insert

      void insert(T entity) throws java.io.IOException
      INSERT INTO .... When the entity has an auto-increment @Id, the generated id is written back into the instance via SELECT last_insert_rowid().
      Throws:
      java.io.IOException

    • update

      void update(T entity) throws java.io.IOException
      UPDATE ... WHERE id = ?.
      Throws:
      java.io.IOException

    • delete

      void delete(T entity) throws java.io.IOException
      DELETE ... WHERE id = ?.
      Throws:
      java.io.IOException

    • findById

      T findById(Object id) throws java.io.IOException
      SELECT ... WHERE id = ?. Returns null when no row matches.
      Throws:
      java.io.IOException

    • findAll

      List<T> findAll() throws java.io.IOException
      SELECT * FROM .... Returns every row mapped to an instance of the entity class.
      Throws:
      java.io.IOException

    • find

      List<T> find(String where, Object... params) throws java.io.IOException

      Free-form WHERE clause; where is appended verbatim after WHERE and params fills the ? placeholders.

      users.find("age > ? AND city = ?", 18, "Berlin");
      Throws:
      java.io.IOException