Unable to resolve signature of Typescript decorator when imported from another file

Question

Given the following:

decorator.ts

export function logStuff(target: Object, key: string | symbol, descriptor: TypedPropertyDescriptor<any>) {
    return {
        value: function (...args: any[]) {
            args.push("Another argument pushed");
            descriptor.value.apply(target, args);
        }
    };
}

Shell.ts

// Removed other imports for brevity
import logStuff = require("utils/log-decorator");

class Shell extends AnotherClass {
    constructor() {
        super();
        this.fooMethod("arg1");
    }

    @logStuff
    private fooMethod(arg1: string, arg2?: string) {
        console.log(`Arguments from original function: ${JSON.stringify(arguments)}`);
    }
}

export = Shell;

I get this message (shortened the file path for brevity):

Unable to resolve signature of method decorator when called as an expression. Cannot invoke an expression whose type lacks a call signature. Type 'typeof "/utils/log-decorator"' has no compatible call signatures

However, if I move the function to the top of Shell.ts, it compiles without errors. Any suggestions on how to handle this?

Answer 1

Your logStuff is available as an exported member of the module. So you have to access it like:

import logStuffModule = require("utils/log-decorator");
//...
@logStuffModule.logStuff
private fooMethod(arg1: string, arg2?: string) { ... }

---

Or use ES6-style imports:

import { logStuff }  from "utils/log-decorator";

// ...
@logStuff
private fooMethod(arg1: string, arg2?: string) { ... }

---

Or you can modify your module by setting the export object as your function and use it like how you are using it now:

 // decorator.ts export = function logStuff() {} // Shell.ts import logStuff = require("utils/log-decorator"); // ... @logStuff private fooMethod(arg1: string, arg2?: string) { ... }