Library schematic conflicts with itself when used with applyToSubtree

[CobusKruger]

🐞 Bug report

Command (mark with an x)

- [ ] new
- [ ] build
- [ ] serve
- [ ] test
- [ ] e2e
- [ ] generate
- [ ] add
- [ ] update
- [ ] lint
- [ ] xi18n
- [ ] run
- [ ] config
- [ ] help
- [ ] version
- [ ] doc
- [X] schematics

Is this a regression?

Not that I'm aware of.

Description

I tried to create a schematic that would create an Anglar application and then create a library within that application, but the library schematic wouldn't run in the folder created by ng-new. That's explained in issue #16080, which is distinct from the issue I'm reporting here. It serves as background about why I needed to use applyToSubtree.

When I execute the library schematic within applyToSubtree, it seems to find the right folder and generates a list of files, but it then conflicts on the library's module file. To be clear, the library schematic creates a new file in a new folder and then fails with a merge conflict. I suspect that's because it calls schematics in turn to create a module, component and service.

Whichever way, there is no apparent way to get around this, because the merge happens within the library schematic itself and I'm not given the chance to supply a MergeStrategy.

Just because I know someone will ask: No, the file does not exist outside of the schematic and it was not created by the ng-new call.

🔬 Minimal Reproduction

You can find a minimal reproduction in this repo

Here's an abstract. I use this factory:

export function createProject(_options: any): Rule {
  return (_tree: Tree, _context: SchematicContext) => {
    return chain([
      externalSchematic('@schematics/angular', 'ng-new', optionsApp),
      applyToSubtree('NewAngularAppWithSubtree', [
        externalSchematic('@schematics/angular', 'library', optionsLib)
      ])
    ]);
  };
}

NewAngularAppWithSubtree is the path created by the ng-new call. A merge error then occurs on this file: /NewAngularAppWithSubtree/projects/new-lib/src/lib/new-lib.module.ts. Note that this file was created by the library schematic, not by ng-new.

🔥 Exception or Error

An error occured:
Error: A merge conflicted on path "/NewAngularAppWithSubtree/projects/new-lib/src/lib/new-lib.module.ts".
    at C:\Users\cobusk\AppData\Roaming\npm\node_modules\@angular-devkit\schematics-cli\node_modules\@angular-devkit\schematics\src\tree\host-tree.js:132:35
    at Array.forEach ()
    at HostTree.merge (C:\Users\cobusk\AppData\Roaming\npm\node_modules\@angular-devkit\schematics-cli\node_modules\@angular-devkit\schematics\src\tree\host-tree.js:121:23)
    at ScopedTree.merge (C:\dev\scratchpad\scaffolding-tests\AngularProjectMergeIssues\node_modules\@angular-devkit\schematics\src\tree\scoped.js:72:20)
    at MapSubscriber.project (C:\dev\scratchpad\scaffolding-tests\node_modules\@angular-devkit\schematics\src\rules\schematic.js:42:19)
    at MapSubscriber._next (C:\dev\scratchpad\scaffolding-tests\node_modules\rxjs\internal\operators\map.js:49:35)
    at MapSubscriber.Subscriber.next (C:\dev\scratchpad\scaffolding-tests\node_modules\rxjs\internal\Subscriber.js:66:18)
    at TapSubscriber._next (C:\dev\scratchpad\scaffolding-tests\node_modules\rxjs\internal\operators\tap.js:65:26)
    at TapSubscriber.Subscriber.next (C:\dev\scratchpad\scaffolding-tests\node_modules\rxjs\internal\Subscriber.js:66:18)
    at TakeLastSubscriber._complete (C:\dev\scratchpad\scaffolding-tests\node_modules\rxjs\internal\operators\takeLast.js:71:29)

🌍 Your Environment

     _                      _                 ____ _     ___
    / \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|
   / △ \ | '_ \ / _` | | | | |/ _` | '__|   | |   | |    | |
  / ___ \| | | | (_| | |_| | | (_| | |      | |___| |___ | |
 /_/   \_\_| |_|\__, |\__,_|_|\__,_|_|       \____|_____|___|
                |___/
    

Angular CLI: 8.3.1
Node: 12.12.0
OS: win32 x64
Angular: undefined
...

Package                      Version
------------------------------------------------------
@angular-devkit/architect    0.803.1 (cli-only)
@angular-devkit/core         8.3.17
@angular-devkit/schematics   8.3.17
@schematics/angular          8.3.1 (cli-only)
@schematics/update           0.803.1 (cli-only)
rxjs                         6.4.0
typescript                   3.5.3

[pfeileon]

I have the same issue when creating a custom project analog to this tutorial and then trying to create a lazy module with route.
The first issue is that when the module schematic calls the component schematic, the root path is wrong. This can be solved by adding an execution context {scope: [projectName]} and removing the [projectName] from the path.¹ But then the CLI reports:

Error: A merge conflicted on path schematics route [pathToLazy.module.ts]

When I don't add a scope and instead hack getWorkspace(...) to add the project name to the path for the component schematic, only, there is no error and it works.

^{1 The module, pipe and service schematics all work fine, only directive and component are writing a root path (which is missing the project name) to the tree.}

[d-koppenhagen]

Same issue here.

@pfeileon you wrote:

When I don't add a scope and instead hack getWorkspace(...) to add the project name to the path for the component schematic, only, there is no error and it works.

Would you mind to share your "hacked" getWorkspace() solution that works for you? I didn't manage to solve the issue locally by trying out lot's of things with pathes and handing over options etc.

[pfeileon]

By "hack" I mean that I executed my schematics with the value hardcoded into getWorkspace() for investigation purposes. I don't have a solution other than copying the files unfortunately.

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