how to generate URI parameter for dynamic feign basePath using swagger codegen?

Question

I have a pretty simple question :)

According to feign documents, they are supporting in changing the basePath of a feign client object dynamically by passing URI parameter trough the api function like so:

GOOD Example:

interface MyClient {
    @RequestLine("GET /internal-service")
    String internalService(URI baseUrl);
}

The thing is I'm using swagger, who generates my API from a yaml file and adding @Param annotation to all function parameters, which is not good for me.

BAD Example:

interface MyClient {
    @RequestLine("GET {baseUrl}/internal-service")
    String internalService(@Param("baseUrl") String host);
}

Is there a way to make swagger generator to generate an API with a URI param, without the @Param annotation?

Desired Outcome Example:

interface MyClient {
    @RequestLine("POST /internal-service")
    String internalService(URI baseUrl, @Param("someParam") String someParam);
}

To get this you will have to modify both the template and the generator, you can open a issue on github as an enhancement or suggestion for the feign generator since this is part of the language. For start you will have to be able to differentiate the parameter that is the URI in the yaml so that then it can be parsed different in the generator and display correctly in the template and therefor the generated code. — moondaisy, Aug 11 '17 at 04:21
Thanks a lot @moondaisy! u r right, I need to change the template but not necessarily the generator. I can use configuration to make swagger use my new template. Regardless I will suggest this enhancement to swagger as you suggested :) — dorony, Aug 13 '17 at 15:18
That works but it will put the `URI` parameter in all of the methods of all your interfaces, I though you might want to have some without it that's why I suggested modifying the generator. Glad you found a solution! — moondaisy, Aug 14 '17 at 15:17

score 6 · Accepted Answer · answered Aug 13 '17 at 15:55

Initial solution:

After some investigation I came to realize that there is no support in swagger-codegen 2.2.3 for generating URI parameter as part of the client API function.

But there is an option in swagger-codegen-maven-plugin configuration of "templateDirectory - directory with mustache templates", for giving a path to a folder including mustache templates, which will take the templates in that folder and override the existing with the same name.

example:

        <plugin>
            <groupId>io.swagger</groupId>
            <artifactId>swagger-codegen-maven-plugin</artifactId>
            <executions>
                <execution>
                    <id>my-project-api-client-kit</id>
                    <goals>
                        <goal>generate</goal>
                    </goals>
                    <configuration>
                        <inputSpec>${project.build.directory}/my-project-api.yaml</inputSpec>
                        <language>java</language>
                        <configOptions>
                            <dateLibrary>java8</dateLibrary>
                            <sourceFolder>src/main/java</sourceFolder>
                        </configOptions>
                        <modelPackage>my.project.ck.resources.models</modelPackage>
                        <apiPackage>my.project.ck.resources.interfaces</apiPackage>
                        <library>feign</library>
                        <templateDirectory>/myTemplateFolder/</templateDirectory>
                    </configuration>
                </execution>
            </executions>
        </plugin>

And inside the custom templates folder, put your own api.mustache file with the additional "URI basePath" parameter:

...
{{#returnType}}{{{returnType}}} {{/returnType}}{{^returnType}}void {{/returnType}}{{nickname}}(URI basePath, {{#allParams}}{{^isBodyParam}}{{^legacyDates}}@Param("{{paramName}}") {{/legacyDates}}{{#legacyDates}}@Param(value="{{paramName}}", expander=ParamExpander.class) {{/legacyDates}}{{/isBodyParam}}{{{dataType}}} {{paramName}}{{#hasMore}}, {{/hasMore}}{{/allParams}});
...

Note: Swagger provides a lot of templates for a variety of uses, make sure to take and modify the correct api.mustache template file according to which you are using. in the above example I modified (and override) the java.libraries.feign/api.mustache file because this is the file my plugin is configured too (as in the example).

how to generate URI parameter for dynamic feign basePath using swagger codegen?

1 Answers1