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Data extractor

To help you with migrating from your existing solution to RedG you can use the RedG extractor. It enables you to extract all the data from a database and create a RedG data set that, if inserted, will produce the exact same database content.

Note

The RedG data set will contain every column from every table. This does not make use of RedG's greatest features (default values, dummy generator). Use the extraction result as a starting point and then reduce your data to the needed minimum. This has to be done by hand, as RedG does not know what data you really need.

Java API

If you have your current test data only available in-memory during your tests, use the Java API of the extractor to generate the RedG Java code.

The generation is a three-step process:

1. Get the RedG TableModels for all tables you want to extract
2. Extract all the data into EntityModels
3. Generate the code for the EntityModels

Obtain the TableModels

There are multiple ways of obtaining the TableModels for your database schema. RedG writes a serialized table model into every generated entity class code.

These can be accessed at runtime via the static getTableModel() method. If the generated classes are either not yet compiled or compiled but not loaded in your current JVM instance, you can use the TableModelExtractor.extractTableModelsFromSourceCode(directory, codePackage, classPrefix) or TableModelExtractor.extractTableModelFromClasses(directory, codePackage, classPrefix) methods to extract the TableModels for all RedG entity classes.

These two methods take three parameters:

Parameter	Explanation
directory	The Path of the source code root, without the package structure folders
packageName	The name of the Java package that was used during code generation. com.btc.redg.generated if not overwritten
classPrefix	The class name prefix for the generated RedG classes. G by default

Extract all data

Obtain a connection to your database and call new DataExtractor().extractAllData( connection, tableModels). tableModels should be the list of TableModels from the previous step.

Note

If the database you are extracting from is not the same you generated the RedG code from, you might have to change the schema name. To do so, use DataExtractor#setSqlSchema(String schema) to specify the schema name.

Save the result in a list of EntityModels for the next step.

Note

If you manually exclude some TableModels, keep in mind that the extraction will fail if a TableModel for a dependend table (via foreign key) is not found.

Generate the code

Using the EntityModels you can now call new CodeGenerator().generateCode( codePackageName, redGClassName, codeClassName, entityModels)

This will return the Java code as a String. The generated code will be in the default package, so you might need to add your own package x.y.z statement at the top.

The generateCode method takes four parameters:

Parameter	Explanation
codePackage	The code package of the generated RedG entity classes. Needed for imports
redgClassName	The name of your RedG main class. Normally RedG
className	The name that will be used for the class containing your entity specification code
entityModels	The EntityModels from the previous step

Using the generated code

When your database only contains strings and numbers, RedG's extractor will most likely produce working Java code. If you are using dates, blobs or other more "exotic" types that cannot simply be mapped to a Java type, the toString() result will simply be used as a placeholder and you'll have to fix the code.