Ionic 3 get contents of an asset file

Question

I'm building an app to show the contents of a book. I have 3 pages in this app:

Page 1. List of buttons that links to chapters; (ChaptersPage)
Page 2. List of buttons that links to pages of a chapter; (PagesPage)
Page 3. Page content; (PageContentPage)

Pages 1 and 2 are inside a Tab, so when the user selects a chapter he goes to the next tab, then select a page of the chapter and then get the page content. The tabs will look like this:

All pages and chapters are on his own folders. My app folders looks like this:

src
|_ app
|_ assets
   |_ icon
   |_ images
   |_ chapters
      |_ 1
         |_page_1.txt
         |_page_2.txt
      |_ 2
         |_page_1.txt
         |_page_2.txt
      |_ 3
         |_page_1.txt
         |_page_2.txt
      |_  ...
|_ pages
|_ services
|_ ...

First, when the user selects a chapter I need to look how many pages are inside the chapter folder, so I can list the correct number of buttons. I'm trying to use ionic native File plugin but I have no success. Using the example on the file plugin doc I'm always getting "Directory doesnt exist":

this.file.checkDir(this.file.applicationDirectory, 'assets/chapters/2').then(_ => 
   console.log('Directory exists')
).catch(err => console.log('Directory doesnt exist'));

So, my question is: how can I read how many files are inside a chapter folder? and after, how can I get the contents of a page.txt?

Answer 1

readPage() {
    this.http.request('../assets/chapters/1/page_1.txt')
          .map(res => res.text())
          .subscribe(text => {
            this.txtContent= text;
          })
          .catch(error => {
            console.err("Path not found with error:", error);
          });
}