User Defined Objects as Columns

SqliteMagic supports user defined objects as columns (or "complex columns") without any hustle, complications or special configuration. Just define a complex column as a normal column and that's it.

Prerequisite for defining complex columns is that the parent and child objects are both included in the database schema with both having @Table annotations.

Example:

POJO	Result in SQL
@Table(persistAll = true) public class Author { String firstName; String lastName; ... } @Table(persistAll = true) public class Book { String title; Author author; ... }	CREATE TABLE IF NOT EXISTS author ( _id INTEGER PRIMARY KEY AUTOINCREMENT, first_name TEXT, last_name TEXT ); CREATE TABLE IF NOT EXISTS book ( _id INTEGER PRIMARY KEY AUTOINCREMENT, title TEXT, author INTEGER );

Internally, the referenced table id is saved in a parent table (as seen in example: author INTEGER). Note that there is no foreign key constraint - there is no real need for it and in that way, we can keep things simple (e.g. in migrations).

Complex Objects Handling During Persisting

By default, when a parent object is persisted (in the example above it's the Book object), its complex columns are also persisted. In that case, the whole operation is internally wrapped inside a transaction (source code can be viewed in the generated code).

Java	Result in Database
Author author = new Author("Foo", "Bar"); Book book = new Book("The Bar Life", author); long id = book .persist() .execute();	Author: _id first_name last_name ... 73 Foo Bar Book: _id title author ... 42 The Bar Life 73

If the functionality mentioned above is not needed, annotate column with @Column(handleRecursively = false). In that case, only the referenced table id is persisted.

@Table(persistAll = true)
public class Book {
  
  String title;
  
  @Column(handleRecursively = false)
  Author author;
  
  ...
}

Author author = new Author("Foo", "Bar");
Book book = new Book("The Bar Life", author);

// no changes to Author table here
long id = book
    .persist()
    .execute();

ON DELETE CASCADE

If the ON DELETE CASCADE constraint is needed, annotate complex column with @Column(onDeleteCascade = true). The default value is false.

POJO	Result in SQL
@Table(persistAll = true) public class Book { String title; @Column(onDeleteCascade = true) Author author; ... }	CREATE TABLE IF NOT EXISTS book ( _id INTEGER PRIMARY KEY AUTOINCREMENT, title TEXT, author INTEGER REFERENCES author(_id) ON DELETE CASCADE );