pdfMake not creating pdf using File plugin IONIC - ionic-framework

Question

Pdf make not creating pdf using File Plugin on android device. But able to create and download on web.
global packages:
Cordova CLI : 7.1.0
local packages:
#ionic/app-scripts : 2.1.4
Cordova Platforms : android 6.3.0
Ionic Framework : ionic-angular 3.6.0
packages.json
"#ionic-native/file": "^4.20.0",
"#ionic-native/file-opener": "^5.0.0"
Here is the code below
print() {
this.createPdf();
if (this.plt.is('cordova')) {
this.pdfObj.getBuffer(function (buffer) {
let utf8 = new Uint8Array(buffer);
let binaryArray = utf8.buffer;
var filename = this.formname + new Date().toDateString();
this.file.writeFile(this.file.documentsDirectory, filename+'.pdf', binaryArray, { replace: true }).then(fileEntry => {
const toast = this.toastCtrl.create({
message: 'File saved to your device',
duration: 3000,
position: 'top'
});
toast.present();
this.fileOpener.open(this.file.documentsDirectory + filename+'.pdf', 'application/pdf');
})
});
} else {
this.pdfObj.download();
}
}
createPdf() {
for (let item of this.columns) {
this.columnRelDataForPdf.push(this.formData[item.columnDef])
}
console.log("Inside create pdf");
console.log(this.columnDataForPdf);
console.log(this.columnRelDataForPdf);
var bodyData = [];
var dataRowHeader = [];
dataRowHeader.push(this.formName)
dataRowHeader.push('')
bodyData.push(dataRowHeader);
for (let item of this.columns) {
var dataRow = [];
dataRow.push(item.header);
dataRow.push(this.formdata[item.columnDef] == undefined ? "" : this.formdata[item.columnDef]);
bodyData.push(dataRow)
}
var docDefinition = {
content: [
{
layout: 'lightHorizontalLines',
table: {
headerRows: 1,
widths: ['*', '*'],
body: bodyData
}
}
], styles: {
header: {
bold: true,
fontSize: 20,
alignment: 'right'
}
}
};
this.pdfObj = pdfMake.createPdf(docDefinition);
}
I tried externalDataDirectory and other options as well but no luck with the pdf file creation. Please let me know where am i doing wrong.
Thank you.

Answer 1

Do:
File.writeFile(File.externalRootDirectory, filename+'.pdf', binaryArray, { replace: true }).then(fileEntry =>
instead of:
this.file.writeFile(this.file.documentsDirectory, filename+'.pdf', binaryArray, { replace: true }).then(fileEntry =>