Electron - Not allowed to load local resource

Question

Evening,
I'm looking into using electron to package an existing angular2 build. I thought I had a dry run working but the actual packaging seems to be failing (see final step below) and I want to understand why. Here's what I'm doing...

Create Project
Use angular-cli to start a new project ng new electron-ng2-cli --style=scss

Install electron and electron-builder

Edit package.json
Make the following additions...
"main": "main.js"

"build":
{
  "appId": "com.electrontest.testapp",
  "mac": {
    "category": "your.app.category.type"
  }
}

and add the following to the scripts...

"pack": "build --dir",
"dist": "build",
"electron": "electron main.js",
"postinstall": "install-app-deps"

Create main.js
I just copied the code from the electron quick start. The only change I make is to the location of index.html which I set to /dist/index.html

Amend base
In index.html change <base="/"> to <base="./">

Pack code
Run ng build. This puts all the packaged code in /dist

Test Run
Run npm run electron. This works fine. An Electron app fires up and I see the angular stuff running within it.

Create App For Distribution
Run npm run pack to create a packaged app. The packaging seems to go ok - I get a warning about a missing icon and a warning that my code is unsigned but I'm guessing they shouldn't be fatal?
The problem is that when I now run the app by double clicking in Finder I get an error in the console saying: Not allowed to load local resource: file:///Users/<username>/Documents/development/electron-ng2-cli/dist/mac/electron-ng2-cli.app/Contents/Resources/app.asar/dist/index.html

---

So, can anyone explain what is different between the packaged app that fails and the one that runs ok when I use npm run electron?

What can I do to fix this issue and get the app running correctly?

Thank you for making it to the end. This got longer than I wanted but I hope I explained myself ok. If you can help or give any pointers that would be great - many good vibes will be thought in your general direction :)

Cheers all

Answer 1

It took a lot of trial and error but I got this working. There is a lot here that I don't totally understand, and much that might be pointless or bad practice and it might all fall down at the very next step but if, like me, you are just trying to get over the first hump then maybe something I found will help you.

I found the problem by unpacking the app.asar file that electron-builder produces. Instead of containing the bundled code from my dist folder it contained all the project code (*.ts *.scss etc). The problem was just that the packing functions were packing up the wrong stuff.
The steps to get the right source into the final app are simple when you lay them out but my god they didn't half put up a fight! Starting from where I left off in my initial question I did the following...

Remember that my project structure is the default one set up by angular-cli

Electron specific files
I moved the main.js down into src and changed its name to electron-main.js just to stop any confusion with the main.ts that is already in there. I also changed the path it references back to /index.html.
Next I created a new application level package.json also in src and gave it the following content:

 {
  "name": "application-name",
  "description": "CLI app",
  "author": "Me me me",
  "version": "0.0.1",
  "main": "electron-main.js"
}

angular-cli.json
I changed the outDir to build purely because electron seems to output to dist by default and I wanted some separation at this stage. Then I affffded package.json and electron-main.js to the assets array.

Main package.json
I removed the "main":"main.js" as it is apparently no longer needed here. In scripts I changed the test command to electron build to point it at the build folder where the bundled code will be.
Finally, I went to the build field and added the following content:

"directories": {
  "buildResources": "build",
  "app": "build"
}

Seems pretty obvious now. This just tells the compiler where to look for the assets that will make up the final app. It was defaulting to the working directory and that was my problem.

Using this setup I can now run ng build to bundle my project into the build folder along with the electron-main.js and package.json.
This done I can run npm run electron to quickly launch a test app or npm run pack to build an app that can be launched from Finder.

Boom. Job done. I'll be back here in ten minutes with another annoying question I expect. Gotta love the dev these days :)

Answer 2

Just change the BrowserWindow' options: new BrowserWindow({ webPreferences: { webSecurity: false } }) If window's url points to a remote source, like http://..., browser will not allow to load local resource, unless you set the options above.

Answer 3

In case this helps anyone, thhe issue I was having was I had the path set using process.cwd():

win.loadURL(`file://${process.cwd()}/dist/index.html`);

Which when packaged is not correct since the the main.js file is not in the root anymore. Changing to __dirname:

win.loadURL(`file://${__dirname}/dist/index.html`);

Fixed the issue for me.

Answer 4

Problem may be the invalid path in main.js, correct it if necessary

Answer 5

I had the same problem. This worked for me

// and load the index.html of the app.
  window.loadURL(url.format({
    pathname: path.join(__dirname, 'dist/index.html'), // important
    protocol: 'file:',
    slashes: true,
    // baseUrl: 'dist'
  }));