OpenAPI 3.0 Parser in Kotlin

Latest Version: 2.1.1

Project Description

This open-source project provides an OpenAPI 3.0 Parser implemented in Kotlin, utilizing immutable data classes. In contrast to Swagger Parser, this parser employs immutable data classes for clearer and safer data manipulation.

License

This project is licensed under the Apache License 2.0. See the License file for details.

Features

• OpenAPI 3.0 Parsing: The parser allows reading of OpenAPI 3.0 specification files into kotlin data classes.
• Serialisation: Allows to convert OpenAPI 3.0 entities into YAML or JSON.
• Immutable Data Classes: Instead of mutable data structures, like in swagger-parser, immutable data classes are used to ensure code safety and clarity.
• OpenAPI as Code: Allows you to define OpenAPI 3.0 Entities in Kotlin (or Java) Code.
• Automatic Code Generation: The majority of the code is automatically generated to ensure code maintainability and consistency.
• Nullable The Implementation uses a Class called Field<T> to handle attributes that are set to null and to distinguish them from attributes that are not set

Unsupported Features

• OpenAPI Validation: Validation is currently not supported.
• Conversation from/to swagger-parser: You can simply take an intermediate step via YAML/JSON.
• Kotlin Multiplatform: Currently, only JVM is supported, but adding other Platforms should be easy.
• Other YAML/JSON Libraries: Due to the automatic code generation, it would be easy to create interfaces for a basic implementation as well as different data classes for different YAML/JSON implementations. There is already a wrapper class (Wrapper)

Feel free to contribute and extend the project, merge requests are very welcome!

Code Generation

The majority of the code is automatically generated, and you can update the generated code using the command ./gradlew codegen:run. You can find the Code Generation in Folder codegen/, the generated classes can be found in src/generated/kotlin and the generated unit tests in src/generatedtest/kotlin. Code Generation is implemented using Mustache Templates, the templates can be found in Folder codegen/src/main/resources/templates.

Installation

To use the project, you can include it in your Gradle or Maven project as follows:

Gradle

build.gradle

implementation 'io.github.lancomsystems.openapi.parser:openapi-parser:2.1.1'

build.gradle.kts

implementation("io.github.lancomsystems.openapi.parser:openapi-parser:2.1.1")'

Maven

<dependency>
    <groupId>io.github.lancomsystems.openapi.parser</groupId>
    <artifactId>openapi-parser</artifactId>
    <version>2.1.1</version>
</dependency>

Usage

val given: Map<String, OpenApi> = // ... Key: API-Name, Value: OpenApi Definition
given.mergeOpenApi(
    default = OpenApi().addInfo(
        Info()
            .addTitle("title")
            .addVersion("0.0.0")
    ),
    patchTag = { name, tag -> "$name:$tag" },
    patchPath = { name, path -> "/cloud-service-$name$path" },
    patchOperationId = { name, operationId -> "$name${operationId.replaceFirstChar(Char::uppercaseChar)}" },
    createTagGroups = true,
)