Blog - kimserey lam

Apr 29, 2017

Aspnetcore Filters

ASP NET Core comes with a concept of filters. Filters intercept the stages of the MVC pipeline and allows us to run code before/after their executions. They are meant to be used for cross-cutting concerns; logics which is required accross the whole application, generally not business oriented. One example is authorization where in a Web API, we would use to prevent unauthorized request to execute the code in our controllers. In order to do that we would have a filter at the entrance of the pipeline. In fact, ASP NET Core has predefine stages, the diagram can be found on the documentation https://docs.microsoft.com/en-us/aspnet/core/mvc/controllers/filters. Another example of a cross-cutting concern would be for logging and timing functions. While the concept of filters is easy to understand, the way to implement those aren’t always straight forward, especially when the filter instantiation itself requires simple objects. In order to illustrate our example we will only filter the Action stage. The same implementations can be applied to any stages of MVC pipeline.

Apr 21, 2017

Aspnetcore Authorization

Last week I touched on how we could authenticate users using Resource Owner Password flow with identity server. Authentication is the act of taking the information provided and verifying the “identity” of the user, ensuring that Alice (our beloved example user) is who she “claims” to be. In the program itself, we take her credentials and verify it and create and identity stating that the user is Alice and has claims A, B and C.

Authentication is the first part of the access security, the second part is the authorization. The difference being that for authorization, we know who the user is, what we are verifying is if Alice is allowed to perform what she is trying to perform. The easiest example is the difference between user access and admin access commonly seen in software where users are authenticated but aren’t authorized to perform all the actions available in the system.

Apr 14, 2017

Authentication With Identity Server

Few week ago I described how to build a custom Jwt authentication. Today I will show how we can use Identity server together with Resource owner password flow to authenticate and authorise your client to access your api.

Apr 08, 2017

Cost Of Living In London

In 2015, I decided to relocate from Singapore to London. At the time I had no idea about the cost of living, the places where I should rent and places where the groceries would be the cheapest. Fast forward to today, March 2017, I moved back from London to Singapore. I stayed around London for more than a year and a half and while I was there, I kept an extremely close look to every in and out from my bank account. I even created an app Expense King to track my expenses coming out from my bank account.

Mar 29, 2017

Understand Bootstrap Flexbox

Last week we saw how to setup vscode to compile sass. Today we will see how we can compile bootstrap sass files together with our own sass and define a grid layout for the collapsed nav in smaller screen using flexbox.

Mar 23, 2017

Setup Visual Code For Sass Development

Writing sass is very easy with code. Today we will see how we can leverage some NPM packages to compile SASS to CSS, watch file changes and live update the browser for an effortless style development.

Mar 16, 2017

Sticky Navbar For Bootstrap

Today I will demonstrate one way to achieve a sticky navbar in Bootstrap v4 using fixedsticky.

Mar 09, 2017

Gimp Tips For Environment

Every now and then I discover features on Gimp that I didn’t know existed. It is always a good surprise to find a feature which simplify your work. So today I will show four features that I recently discovered.

Mar 02, 2017

Websharper Form Engine

WebSharper came out with WebSharper.Forms. It is a terse DSL to build form, I posted a tutorial on it few months ago https://kimsereyblog.blogspot.co.uk/2016/03/create-forms-with-websharperforms.html. It’s very powerful as the abstraction handles most of the scenarios. Today I would like to show anothe way to create forms by building a form engine.

Feb 21, 2017

Post Form Data

When building websites, chances are that you will need to gather data from your users. The most common way to gather data is via a form. But after gathering the data, there are two ways to submit it from the browser to your server; using a HTML form or using an Ajax call

Feb 13, 2017

Websharper Listmodel_local Storage With Ui Next

Last week I wanted to use the browser local storage to store a list of element. I wanted to update the resource split project to have the data stored (temporarily) so that it will be easier to add or remove resources. The browser local storage is ideal for this kind of scenario. Turns out WebSharper.UI.Next has the feature built in to persist ListModel so today I will explain how to do it.

Feb 10, 2017

Visual Studio Not Implemented Error Fsharp Project

Yesterday I had an error prompting me the following error when trying to reference a project within my solution.

Feb 02, 2017

Fix Listmodel Websharper Lost Of Focus

Few months ago, I explained how ListModel worked. Today I would like to share a recurring issue that I used to have - lost of focus on input every time the ListModel values change. There’s an easy solution to that which I will demonstrate by first showing the initial code and explaining what is going on, why the focus is lost, then I will explain how we can work around it.

Jan 28, 2017

Authentication Jwt For Websharper

Authentication is an important part of any Web applications. Today I will explain how we can create the essential modules required to authenticate a user. This post will be composed by four parts:

Jan 20, 2017

Xamarin Ios Splashscreen

Few weeks ago I explained how we can create a splash screen for Android. Xamarin.Forms takes few seconds to load at each start so it is important to provide a feedback to the user when they click on our icon. The splash screen answers that by providing a way to show a loading screen. Today we will see how we can setup a simple splashscreen with an image centered and with a text label.