[docs] Fix imports for x-grid-data-generator

[DanailH]

In response to this comment #855 (comment)

I'm not sure if the x-data-grid-generator is supposed to work with just the data-grid module. Let's discuss it here. Also if it should work then the name would also need to change IMO (remove the x- prefix).

[oliviertassinari]

I'm not sure if the x-data-grid-generator is supposed to work with just the data-grid module.

OK, so we are going with option 1. sounds fair. Considering that XGrid extends DataGrid, I would expect it to work with both. We need to fix the codesandbox dependency generation logic and update all the imports as well as the peer dependency.

Also if it should work then the name would also need to change IMO (remove the x- prefix).

Regarding the naming, if we were to improve it (in the future), I would personally suggest that we create a new repository under this folder: /packages/material-ui-x. Then, we could do import {} from '@material-ui/x/dataGenerator';.

I have also noticed that we forgot to prefix the relevant folders with material-ui in https://github.com/mui-org/material-ui-x/tree/master/packages to match https://github.com/mui-org/material-ui/tree/master/packages.

[DanailH]

I understand that it is still broken. I opened the PR to use it as a discussion to decide between option 1 and option 2.

[DanailH]

After giving it a bit more thought, removing data-grid from the dependencies looks like the way to go. I had to duplicate the v5 helpers which can be removed once we decide to fully migrate so that code is only temporary. The cell definition is needed.

[oliviertassinari]

What's the pros of option 2 compared to option 1? I mean, what's the selling point?

(assuming this terminology #855 (comment))

[DanailH]

Removing DataGrid from the dep would make using this simpler as you can use it with both right. Correct me if I'm wrong but if we keep it as it is and want to make it work with x-grid then you would need data-grid installed as well right, how else could you know from where to import the CellParams for example?

[oliviertassinari]

@DanailH OK thanks. I was interested in the rationale. We trade of bit of code duplication for one less dependency in the codesandbox-es/examples repo (when using x-grid). No objections, we can give it a try.

Could we update the eslint rule to forbid imports, so we don't break the tradeoff in the future inadvertently like we did in the first place?

[dtassone]

We could move it to the grid folder as well, and build it the same way we build data-grid and x-grid package.
So we remove the dependency on DataGrid and we don't duplicate code

[DanailH]

Ok, I moved the x-grid-data-generator under packages/grid and fixed the build (made it the same way it is done for the data-grid and x-grid) and removed the duplicated code.

[oliviertassinari]

Looks great