Import 'cannot find module' when internal module has imports declared - import

Question

I have this namespace
namespace Validation {
export function Func1() {
// code
}
export function Func2() {
// code
}
}
Which I can import in my app.ts:
import Validations = Validation;
But when I want to reference some modules in my Validation namespace
import {Request, Response} from 'express';
var jwt = require('jsonwebtoken');
var express = require('express');
import {Config} from './../config';
namespace Validation {
export function Func1() {
// code
}
export function Func2() {
// code
}
}
So then import Validations = Validation; in my app.ts giving me an error cannot find namespace Validation.
Why it is happened? Any thoughts how to fix?
UPDATE 1 : In case if I put imports after namespace I am getting an error Import declaration in a namespace cannot import a module:
namespace Validation {
import {Request, Response} from 'express'; //Error: Import declaration in a namespace cannot import a module
var jwt = require('jsonwebtoken');
var express = require('express');
import {Config} from './../config'; //Error: Import declaration in a namespace cannot import a module
export function Func1() {
// code
}
export function Func2() {
// code
}
}
my config.ts is just a simple class:
export class Config {
public static get Secret():string { return 'stuff'; }
public static get Database():string { return 'mongodb://127.0.0.1:27019/test'; }
}
And 'express' it is an npm package
UPDATE 2
I think I just fixed config by wrapping it in to namespace:
namespace Common {
export class Config { .. }
}
Also changed import statement from this import {Config} from './config'; to this: import Config = Common.Config; but haven't yet figure out how to fix 'express' thing

Answer 1

This happens because from the moment you put a top-level import or export statement into a file, that file is treated as an external module itself. If you are using internal modules (namespaces), I suggest importing inside namespaces, so that there are no top-level import or export statements.
namespace Validation {
import Request = ...;
import Response = ...;
export function Func1() {
// code
}
export function Func2() {
// code
}
}
The other approach would be to use external modules instead, but that requires a module loading system, which might be superfluous in many cases.
Right now, you are mixing internal and external modules, which is not recommended. Regarding complex structural cases like this, Typescript is still very far from being a mature language.

Answer 2

I assume that you have defined your validation functions in the separate (from app.ts) file. If this is the case then what you need to do is:
In your Validation.ts:
export function Func1() {
// code
}
export function Func2() {
// code
}
In your app.ts:
import * as Validation from './Validation';
Validation.Func1();
Your problem is most likely in mixing together concepts of modules and namespaces in typescript. Have a look here: Namespaces and Modules, and be sure to look through Modules and Namespaces