[SOLVED] How to dynamically change resource URL path in Ballerina?

How to dynamically change resource URL path in Ballerina?

Is it possible to change the resource url of a Ballerina service dynamically.

For an example,

resource isolated function get <DYNAMIC_CONTEXT>/[string resourcePath]() {
    //;
}

In above code, can we set the <DYNAMIC_CONTEXT> dynamically?

My actual objective here is to define this <DYNAMIC_CONTEXT> from the Config.toml or similar manner. So EoD, we are capable of configuring the <DYNAMIC_CONTEXT> on deployment of the service. The end user always has to follow that specific context path which is fixed from their end of view.

Solution

The easiest way is to define the <DYNAMIC_CONTEXT> as a path parameter and, to use a configurable variable (which we can use to provide it's value at the runtime) as shown below.

import ballerina/http;

const PORT = 9090;
configurable string dynamicContext = ?;

service / on new http:Listener(PORT) {
    resource function get [string dynamicContext]/[string resourcePath1] () returns error? {
        // Do something
    }
}

If you want to change the base path dynamically, you can use listener lifecycle method to attach. The service can be defined as either a class declaration or a constructor expression. When attaching the service to the listener, the attach() method can take a variable as the base path which is the second argument.

import ballerina/http;

const PORT = 9090;
configurable string dynamicContext = ?;
listener http:Listener hl = new(9090);

public function main() returns error? {
    check hl.attach(mockService, dynamicContext);
}

http:Service mockService = service object {
    resource function get [string resourcePath1] () returns string {
        return "Mock invoked!";
    }
};