This document provides an overview of using Swagger code generation to automatically generate RESTful web services code from an OpenAPI Specification (OAS) file. It describes a two-step process where Swagger codegen first generates an OAS file from database schema metadata, then uses that file to generate the Spring Boot code. Key parts that will be generated include REST controllers, services, and data access object (DAO) classes. Customizations are required via custom codegen templates and configuration files. The detailed steps to generate the code via a request to the codegen tool are also outlined.

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Spring boot REST data service code generation using Swagger code gen

2. Why use Automatic Code Generation?
Automatic Code Generation refers to using programs to generate
code that the user would otherwise have to write themselves.
Automatic code generation has certain advantages over traditional
coding.
• Correctness
• High quality
• Efficient use of the resources
• Quick code generation
• Consistent
• Coding Abstractly

3. Two step approach.
Two step approach to generate the REST code using swagger code gen.
• Swagger code gen tool reads the table meta data details from DB
schema and generates the YAML file with Open API specs.
• It generates the REST code based on the YAML file.
Methodologies used to generate the code :
• Bottom up approach with online mode

4. Approach Diagram:

5. Important code blocks of REST Services to
be generated by the Swagger code gen.

6. Swagger Custom Code Gen:

7. Swagger Custom Code Gen:
• Default Swagger CodeGen generates only REST Controller of the
spring boot project. Swagger custom code generator implementation
is required to customize the REST controller, Service and DAO classes.
• Swagger custom CodeGen implementation contain following
important files:
• CustomTemplate Codegen file
• Mustache files
• Configuration files.
• Mustache file acts as templates for code generation.

8. Detailed steps to generate REST code.
• Deploy the YAML generator jar file to respective server.
• Post a request to the URL of YAML generator with schema name and table name.
o Sample URL: http://vdalhdpedged013.kbm1.loc:2020/codegen
o Input :Sample Request:
{
"schemaName":"CNTCT_PNT_CONSUMER",
"tableName":"CNTCT_PNT"
}
o Output : Swagger YAML file
• Deploy the Custom swagger code gen jar file to the respective server.
o Input : Swagger YAML file
o Include package structures and other configuration details as part of customConfig.json
o Execute the below command
o java -jar targetCustomTemplate-1.0-SNAPSHOT.jar generate -l spring -i swagger.yaml -o test -c customConfig.json
o Output : Spring boot REST data service code.
• Deploy generated Spring boot REST code and test the CURD operations of the Phoenix REST data services.

9. Next steps..
• Junit test cases implementation with good coverage.
• Preprocessor and post processes of request and response for processing.
• Client stub generation for given service through YAML.
• Open API documentation through YAML file.
• Error and Exception handling.
• REST wrapper generation for given soap code ( This is a huge
implementation).
• Different configuration files Implementation like security, environment
specific configuration (API gate way, service discovery configuration may
require in feature).
• Transaction management code implementation.
• Pom file generation based on dependencies.