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| simpleorm.quickstart | ||
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SimpleORMGenerator
SimpleORMGenerator provides a simple way of generating the SimpleORM class files for an existing database. Since SimpleORMGenerator uses the meta data extracted from the database the class files produced should exactly match the database's schema. Class files producedEvery table produces two class files, a base class that contains the field definitions and a public class that extends the base class. Example given table EMPLOYEE file Employee_base.java
class Employee_base {
File Employee.java
public class Employee extends Employee_base{
The Employee_base class is defined as package private, which means that it can't be seen from outside of the package. All interaction to the database table has to pass through Employee and therefore through any business rules that you add. The base class is regenerated every time SimpleORMGenerator is run, while the public class is only generated if it does not exit. This allows you to edit the pubic class to your hearts content and still be easily update your classes with any changes made to the database. Getters and SettersSimpleORMGenerator produces getters and setters for every field in the table. As these methods are creates automatically there is no method maintenance is required. Having getters and setters makes it easy to insure that the correct data type is passed to a field at compile time instead of runtime. Example
public String get_NAME(){
Foreign references key fields. SimpleORMGenerator does generate code that uses SFieldReference fields to represent foreign keys. This is because SfieldReference fields represent links between tables in a conceptual model of the database. Trying to re-engineer these conceptual links from a physical model has not proved very successful. The mapping is complex and it appears that SimpleORM may contain a number of bugs in this area. To get around this problem SimpleORMGenerator uses a simple solution - getters and setters for reference fields. Example (simplified)
public Department get_DEPARTMENT(){
return Department.findOrCreate(get_DEPT_ID());
One side effect of this approach is that if the classes are to generate database tables, the foreign keys between tables will be lost. The pay off is that there is no type casting required when getting a record! Find or Create methods.SimpleORMGenerator creates a set of static FindOrCreate methods for the classes. These are far simple to use that provided by the meta object as the parameters are implicitly defined. Example
public static Employee findOrCreate( String _EMPEE_ID ){
If a foreign key appears in the primary keys of the table then additional FindOrCreate method will be generated with the foreign key as one of its parameters Example
public static PaySlip findOrCreate( Employee _ref, long _YEAR, long _PERIOD){
Naming of fields
SimpleORMGenerator uses a version of adapter pattern to allow uses to implement their own field name strategy. When running SimpleORMGenerator a class that implements interface simpleorm.quickstart.IniceNameFormatter. This class can then implement the required field naming algorithm. See simpleorm.quickstart.SimpleORMNiceNameFormatter for an example. Running SimpleORMGenerator.The required system properties must be set. Create an instance of SimpleORMGenerator and then call the execute() method. Or do what I do and simply edit the code in the main() method! | ||
| Java Source File Name | Type | Comment |
| AParam.java | Class | |
| ColumnGenerate.java | Class | |
| DefaultFormatter.java | Class | This is the standard name conversion used by SimpleORMGenerator. |
| ForeignKeyGenerate.java | Class | |
| INiceNameFormatter.java | Interface | Interface to convert the database table or column name to your names. SimpleORMGenerate must be created with an object that instanciates this interface. Typically you should simple algrothem to return a nice name (like DefaultFormatter), but the code could be complex as you feel like (like SimpleORMNiceNameFormatter). |
| SimpleORMGenerator.java | Class | This class generates the SimpleORM mapping files for a (in this example) Sybase schema. |
| SimpleORMNiceNameFormatter.java | Class | |
| TableGenerate.java | Class | |