How to make use of Graph<T> / Node<T> types?

[voxpelli]

@dagrejs/dagre exposes eg. Graph<T>, Node<T> types while @dagrejs/graphlib doesn't, but it's not clear how to use these to provide extended values on a node in the graph.

The node is returned using the extended Node<T>:

dagre/index.d.ts

Line 35 in 2216b81

node(id: string | Label): Node<T>;

But there is no way of assigning any T data to it in the first place?

dagre/index.d.ts

Line 43 in 2216b81

setNode(name: string, label: string | Label): Graph<T>;

How are these meant to be used? Considering that the plain types from @dagrejs/graphlib are not used there is a use case I assume?

[Sadret]

Same question here.

[shaywiin]

import { dagre } from 'dagre-d3';
const g = dagre.graphlib.Graph<Your type here>(opt)

@voxpelli

[Sadret]

import { dagre } from 'dagre-d3';
const g = dagre.graphlib.Graph<Your type here>(opt)

@voxpelli

This is not answering the question at all.

[Sadret]

Looking at the type definitions again, the answer is this:

dagre/index.d.ts

Line 132 in c1cf91c

export type Node<T = {}> = T & {

Which means that we can do things like:

type A = {foo: string};
const g: Graph<T> = ...
const n: Node<T> = g.node("node-id");
n.foo = "bar"; // type-safe, known to be a string attribute

[Sadret]

To be fair, this is only type-safe if T has only optional attributes, because:

type A = {foo: string};
const g: Graph<T> = ...
const n: Node<T> = g.node("node-id");
console.log(n.foo); // undefined, but should be string

[shaywiin]

This generic type T in these lines:

dagre/index.d.ts

Line 35 in 2216b81

node(id: string | Label): Node<T>;

and

dagre/index.d.ts

Line 43 in 2216b81

setNode(name: string, label: string | Label): Graph<T>;

come from the class definition:

dagre/index.d.ts

Line 11 in 2216b81

class Graph<T = {}> {

So you need to provide the type when initializing new graph:

import { dagre } from 'dagre-d3';
const g = dagre.graphlib.Graph<Your type here>(opt)

We can then infer the type from those function. Note that we don't need to declare the type for n

type A = {foo: string};
const g = dagre.graphlib.Graph<A>(opt)
const n = g.node("node-id");
console.log(n.foo); // type of n.foo is string

You also can provide the type for Node<T> if you don't want to infer the type:

const n: Node<A> = {...}

This is a very basic typescript syntax, not related to dagrejs at all.
IMO I think we should close this issue

[Sadret]

Once again you fail to understand the question. We are not asking about the syntax of the generic parameter but about how to make use of it in this context, since it does not appear in any method signature. See my comment above which answers the question for me and hopefully also for @voxpelli.
Unrelatedly, note that in your code above n.foo is undefined but supposed to be of type string.