How to map moment to number?

[krukru]

Hi again :)

This time I am wondering how to map between moment object and number

Here is my snippet

import "reflect-metadata";
import { AutoMap, Mapper } from "@nartc/automapper";
var moment = require("moment");

class Foo {
  @AutoMap()
  public get foo(): Moment {
    return this._foo;
  }

  public set foo(value: Moment) {
    this._foo = value;
  }

  private _foo!: Moment;
}

class FooDTO {
  @AutoMap()
  public foo!: number; // the unix timestamp
}

Mapper.initialize(cfg => {
  cfg.createMap(FooDTO, Foo).forMember(
    (dest: Foo) => dest.foo,
    (opts: any) => opts.mapFrom((source) => {
      return moment(source.foo);
    }),
);
});

const foo = Mapper.map({ foo: 1111234567890}, Foo, FooDTO);
console.log(foo);

This fails with the error "TypeError Cannot read property '_isAMomentObject' of undefined".
The issue is related to class-transformer (see typestack/class-transformer#176) but I don't know how to get this to work using your mapper lib.

[nartc]

Hi, thanks for reporting the issue.

I thought about Moment object but ended up not supporting it since it would mean I would need to support another 3rd party library and there are many different choices regarding Date now. If I could suggest, try: date-fns, dayjs or luxon.

However, if Moment is crucial for your project, I’ll see what I can do.

[krukru]

Hey, it is not crucial :)
I don't really like moment due to the way it is written, but decided to go with it since it seemed most used/popular. Maybe it is time to reconsider :)
Thanks anyway, I am closing the issue (and maybe it would be worth noting that moment is not supported)

[nartc]

@krukru Though it is the most popular one, it’s a heavy library.

• Luxon: is written using Moment’s concept but is redesigned to be lighter and less-clunky than Moment, written by one of the old Moment’s maintainer
• date-fns: like Lodash for Date
• dayjs: extremely lightweight with plugin to enable various features.

I’ve used date-fns and dayjs before and they’re great. Working with native JS Date object is awesome with those libs. I would definitely reconsider and will write a small section regarding DateTime on the Readme. Thanks again

[nartc]

@krukru I found a workaround for Moment object. Read the Date Time section on the README to learn about it. Though, I would still suggest going with vanilla JS Date object if you can.

[krukru]

Hey, thanks for updating the docs, I almost got this to work after updating to 3.1.2 :)
Here is what I am working with

import "reflect-metadata";
import { AutoMap, Mapper } from "@nartc/automapper";

import { Moment } from "moment";
const moment = require("moment");

class Foo {
  @AutoMap(() => moment)
  public get foo(): Moment {
    return this._foo;
  }

  public set foo(value: Moment) {
    this._foo = value;
  }

  private _foo!: Moment;
}

class FooDTO {
  @AutoMap()
  public foo!: number; // the unix timestamp
}

Mapper.initialize(cfg => {
  cfg.createMap(FooDTO, Foo).forMember(
    (dest: Foo) => dest.foo,
    (opts: any) => opts.mapFrom((source) => moment(source.foo)),
  ).reverseMap().forPath(
    (dest: FooDTO) => dest.foo,
    (opts: any) => opts.mapFrom((source) => source.foo.unix()))
});

const fooDomainObjectMapped = Mapper.map({ foo: 12345 * 1000}, Foo, FooDTO);
expect(fooDomainObjectMapped.foo.unix()).equals(12345); // this passes as true!

const fooDomainObject = new Foo();
fooDomainObject.foo = moment(54321 * 1000);

const fooDtoObjectMapped = Mapper.map(fooDomainObject, FooDTO);
expect(fooDtoObjectMapped.foo).equals(54321); // this fails, fooDtoObjectMapped.foo is equal to the current system timestamp

So mapping from Dto(Vm) -> Domain model works
But mapping Domain model -> Dto fails and always creates a moment object with the current timestamp. Now that's really odd, isn't it! :)

[krukru]

What's maybe more interesting is how this snippet works on 3.1.0

const fooDomainObjectMapped = Mapper.map({ foo: 12345 * 1000}, Foo, FooDTO);
expect(fooDomainObjectMapped.foo.unix()).equals(12345); // this fails, fooDomainObjectMapped.foo.unix() is equal to the current system timestamp

const fooDtoObjectMapped = Mapper.map(fooDomainObject, FooDTO);
expect(fooDtoObjectMapped.foo).equals(54321); // this throws a runtime error: TypeError: Cannot read property '_isAMomentObject' of undefined

I am trying to deduce from the source and commits between versions what has changed, but it is a bit over my head. Hope this piece of info helps!

[nartc]

hmmm I'll give that a quick run on my test bed.

[nartc]

@krukru plainToClass from class-transformer initializes a new Moment object under the hood. That's a bummer. I don't think Moment is working with this library as of the moment.

[nartc]

@krukru Another point is I run plainToClass against the source (that was passed in Mapper.map(source, DestinationModel)) every time. I just modified the code to where plainToClass is only ran if source isn't a true instance of mapping.source (aka if source is a plain object). If source is a true instance of mapping.source, then it seems like moment is working.

Let me know (if you're still interested) if the latest version works out for you.

[krukru]

I don't know what you did, but in 3.1.2 this now works in both directions!
Thanks very much for all the support, you are awesome :)

[nartc]

@krukru I simply changed the way Automapper interacts with class-transformer a bit. Thanks for reporting.