Creation and Generation

Now that we are set up to use the RASP-Platform, let's dive right in and generate code for our first application.

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Creation of JSON blueprint

Let us create an application which handles CRUD operations for a single class - say playground. During our design phase, we arrive at the following UML Class diagram :

This Diagram can be directly translated to a JSON specification as follows :

{  
	"playground": {  
		"cluster": "DB_PROFILE",  
		"ui": false,  
		"api": true,  
		"display_name": "PlayGround",  
		"fields": {  
			"id": {  
				"index": true,  
				"name": "id",  
				"length": 100,  
				"required": true,  
				"type": "String"  
			},  
			"name": {  
				"index": true,  
				"name": "name",  
				"length": 128,  
				"required" : true,  
				"type": "String"  
			},  
			"latitude": {  
				"name": "latitude",  
				"type": "double"  
			},  
			"longitude": {  
				"name": "longitude",  
				"type": "double"  
			},  
			"total_capacity": {  
				"name": "total_capacity",  
				"type": "long"  
			}  
		}  
	}  
}

We can briefly go over the semantics of the parameters in the JSON file :

1. playground : This is the name of the class and it must coincide with the name of the file (playground.json).
2. cluster : We won't delve into it for the time being but this field specifies the MongoDB cluster name.
3. ui : For now, we will be limiting ourselves to the generation of API end-points, but the rasp-platform is also capable of generating JSON specs to be fed to a front-end engine.
4. fields : Here, we specify the attributes of the created class :
   • name : The name of the attribute
   • type : The data-type to be used - possible values include String, double, long etc.
   • index : Specifies whether the values should be unique
   • required : Specifies whether the field can be null during creation.

We add the JSON blueprint to the following location within our application : src/main/java/{groupId}/{artifactId}/playground.json

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Creating the necessary directories

The following directories need to be created for code generation to work :

1. controller and service : Create directories named controller and service in src/main/java
2. static.ui.json : Create a directory with the file path src/main/resources/static/ui/json to store UI elements created by the Generator.

The following image illustrates the creation of the above directories :

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Adding the Generator class

We will add the following code in a Java file created at src/main/java/{groupId}/{artifactId}/GenerateResource.java :

package org.rasp.raspdemo;  
import platform.defined.ResourceGenerator;  
import platform.util.Util;  
  
public class GenerateResource {  
	public static void main(String []args) throws Exception {  
		String web_app_director = "./src/main/resources/static/ui/json";  
		String controller_dir = "./src/main/java/controller";  
		String controller_package = "controller";  
		if (args.length > 0) {  
			web_app_director = args[0];  
		}  
		if (args.length > 1) {  
			controller_dir = args[1];  
		}  
		if (args.length > 2) {  
			controller_package = args[2];  
		}  
		ResourceGenerator generator = new ResourceGenerator("org.rasp.raspdemo","./src/main/java/org/rasp/raspdemo/");  
		if (!Util.isEmpty(web_app_director)) {  
			generator.setWeb_app_directory(web_app_director);  
		}  
		if (!Util.isEmpty(controller_dir)) {  
			generator.setController_directory(controller_dir);  
			generator.setController_directory_package(controller_package);  
		}  
		generator.generateCode("./src/main/java/org/rasp/raspdemo/", null);  
	}  
}

As you can see, certain paths need to be correctly specified for the Generator to work.

String web_app_director = "./src/main/resources/static/ui/json";  
String controller_dir = "./src/main/java/controller";  
String controller_package = "controller";

The above file paths can remain the same since the controller and UI directories were just created.

ResourceGenerator generator = new ResourceGenerator("org.rasp.raspdemo","./src/main/java/org/rasp/raspdemo/");

Here, supply the correct groupId.artifactId and the path to the parent directory of the GenerateResource.java file.

generator.generateCode("./src/main/java/org/rasp/raspdemo/", null);

Here too, supply the path to the parent directory of the GenerateResource.java file.

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Running GenerateResource.java

At this point, everything is in place for the code generation step to work. Run the GenerateResource.java file to generate the files shown the image below :

You will notice that Controllers, Services, Helpers, Resources and Messages are generated specific to the class described in the blueprint.