Tutorials, tips&tricks, snippets..


Convert a p12 DevExpress/DevExtreme certificate to a keystore one

I use DevExtreme from DevExpress to build multiplatform app.

Since DevExtreme doesn’t support anymore its building tool, I use it only to create a zip package and then I build it with

I had to upload my p12 file in this site, but first I had to convert it correctly.

This command line reached the goal:

keytool -v -importkeystore -srckeystore android_certificate.p12 -srcstoretype PKCS12 -destkeystore myKey.keystore -deststoretype JKS

After you run this command, in the output you’ll see the certificate alias. Use this to import the file in If this is wrong, you’ll get an error while compiling the apk.


Create an iOS certificate and use it on

You can create a multiplatform app with Phonegap. At you can also compile the app and generate ipa/apk files. If you want, of course, to publish it on iTunes/Google Play you have to use a certificate. Here, how to create&use an iOS certificate.

Continue reading “Create an iOS certificate and use it on”

C# core: how to generate a pdf from a html with a xsl stylesheet as base64 stream

My goal was to create a base64 string representing the pdf, then send it to my mobile app and show it to the user (here for more info).

The following code is written using the Select.HtmlToPdf.NetCore package.

Continue reading “C# core: how to generate a pdf from a html with a xsl stylesheet as base64 stream”

Download&open a pdf base64 encoded in Android/iOS cordova/phonegap app

In my app, I need to download a pdf file from my api (base64 encoded, here how to create it), convert it and finally open it. Here how I made it.

Continue reading “Download&open a pdf base64 encoded in Android/iOS cordova/phonegap app”

String replace in SQL Server database table

Here a fast snippet

update my_table
set path = replace(path, 'oldstring', 'newstring')

If useful, you can also set a where condition.

Round number keeping trailing decimals without using string

I need all values to rounded to 8 decimal places. So, for example, 1.2 should round to 1.20000000, but Math.Round(value, 8) rounds to 1.2.

I’m using a C# class to populate and then serialise to xml. One of the values is a double. If I assign a ‘1.2’ to the value this gets serialised to ‘1.2’ when I actually need ‘1.20000000’.

I found this fast way to do this without converting the number to string:

foo = doubleValue + 0.00M;

And that makes the value 1.20000000 instead of just 1.2. This was better then doing a ToString and then parsing it back.

Disable onClick after first click to avoid double (or more) clicks

In my app (but this is valid also for web app), I have a problem: if user clicks twice (or more), twice requests (or more) are sent to the API server. Here a snippet to avoid this behavior with useless requests.

var pending = false;

function Foo(param)
    // test to see if something else set the state to pending.
    // if so... return, we don't want this to happen.

    pending = true; // raise the flag!

    /* ... later ... */
    // in the success method of your AJAX call add:
    pending = false;

SQL Group By Date.Day

Another fast snippet: how to group by the from a date/datetime column.

select sum(amount) as total, dateadd(DAY,0, datediff(day,0, created)) as created
from sales
group by dateadd(DAY,0, datediff(day,0, created))

Convert a List<int> to a List<int?>

Here a very fast but useful snippet:

List<int?> nullList = myIntList.ConvertAll<int?>(x => x);

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