List of Posts written during Aug 2021

This is a list of of posts written during the month Aug 2021
(Rev. 28-Jun-2024)

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List of Posts

This is the complete list of categories of posts written during Aug 2021. They have been ordered by the publish date, with the most recent first.

  1. Published: 01-Aug-2021
    Software Engineers use Big O notation to get a quick estimate of the time taken by an algorithm to process "N" items of data. The most typical values are explained below.

  2. Published: 04-Aug-2021
    Considering the elements F, Cl, O and N, the correct order of their chemical reactivity in terms of oxidizing property is: (a) F > Cl > O > N (b) F > O > Cl > N (c) Cl > F > O > N (d) O > F > N > Cl

  3. Published: 05-Aug-2021
    Looking for the "protected" App_Data folder in ASP.NET Core? The news is that it doesn't have that status anymore. It is no longer a "Special" folder. However, a workaround exists, and I demonstrate it in this tutorial. This tutorial explains how to read the contents of a notepad file (located in a "protected" folder of any random name). The contents are read from within the application, and displayed. Later we verify that the same notepad file cannot be accessed from the browser. This concept can easily be extended to use XML as a database, a topic we shall explore in some future posts.

  4. Published: 06-Aug-2021
    This is the simplest example of reading and updating a record. For simplicity, the record consists of just one property called Name. An input textbox is used to display the "Name" and the same textbox is used to post the updated value. Reading and writing is done with the built-in XMLSerializer class.

  5. Published: 07-Aug-2021
    This is a walkthrough on how to make calls to an XML database via repository pattern and dependency injection. We also give a brief introduction to the repository pattern and dependency injection, and also explain the associated benefits.

  6. Published: 08-Aug-2021
    Here is a to-the-point tutorial on how database connectivity works in ASP.NET Core. A 3-step roadmap is laid for running your first query to a database of your choice. The tutorial concludes with an example walkthrough on adding nuget packages for a sqlite database. The actual database connectivity is done in later tutorials.

  7. Published: 12-Aug-2021
    A form of only one input textbox is POSTed and the data is inserted into a sqlite database. This is a six step walkthrough that starts from creating a model, followed by a DAL based on the DbContext class. We also explain how an application is configured for dependency injection of the DbContext, and also, how the DbContext is extracted from the constructor of a PageModel class, and ultimately used to run a database query.

  8. Published: 13-Aug-2021
    We start this walkthrough with a small introduction to the concept of a cookie, and then we explain the various ASP.NET Core snippets to (a) create a cookie, (b) read a cookie and (c) delete a cookie. And lastly, we create a fully functional application for creating and deleting cookies. You can run the application to see the whole concept in action! We strongly recommend that you watch the linked video for finer details.

  9. Published: 14-Aug-2021
    This is a walkthrough on how to obtain user consent for usage of cookies on an core website. This project uses the ITrackingConsentFeature interface to determine if the user has already given his consent, and also to obtain the correct cookie string as per the http format. The readymade functions of this interface make it extremely easy for a developer to obtain a user's consent.

  10. Published: 15-Aug-2021
    _ViewImports.cshtml is shared by all the razor pages in its peer directory, and in the sub-directories below it. It is like an include file, and it is used to type a list of common directives that would otherwise have to be typed in each of the razor pages. A razor page takes into account the entire hierarchy of _ViewImports files above it.

  11. Published: 16-Aug-2021
    This is a comprehensive discussion on the need for "areas", and how to practically create "areas", and how, un-like classic MVC, routing occurs out-of-the-box when razor pages are used. We also discuss how tag helpers help us create proper anchor links to pages inside areas. In the end we present a practical login and authorization scheme for projects that use areas.

  12. Published: 18-Aug-2021
    Razor components are stand-alone, embeddable units that replace themselves with pure HTML, CSS and JS markup. They can accept parameters from the host page. We discuss below how they differ from partial pages, and we also discuss the structure of a component page, and also how to use the <component> tag to easily embed a component into a razor page.

  13. Published: 23-Aug-2021
    So this article starts by explaining the various aspects of a partial view from a practical, day-to-day perspective. We have totally removed those parts that are either redundant or too complicated to be of any use for a practical developer. Then we take a small 3-step walkthrough that shows how to create a partial view, and how to consume it in a razor page. We also explain how a conditional menu can be conveniently implemented using the ideas of partial views. Partial Views + Razor Components can add to the confusion of a developer, so we finally conclude with a comparison with razor components.

  14. Published: 24-Aug-2021
    This article explains behind-the-scenes mechanism by which "Session" is implemented in ASP.NET Core. We also enumerate the four extension methods that ASP.NET Core provides for reading and writing session variables. After that we present a walkthrough where existence of a Session key is checked to conditionally show a login link, or to show her user-name along with a log-off link that clears the user-name from the Session cache.

  15. Published: 26-Aug-2021
    This tutorial continues from where we left the tutorial on INSERT query (see the link below for a recap). The code we discussed there has been extended to display the inserted data. In the first part of this tutorial we explain the minimal three basic things that must be done to display data on a razor page. Then we incorporate those additions into the index page and its backing class to show the whole idea in action.

  16. Published: 27-Aug-2021
    There is no built-in method for storing DateTime into a session variable in ASP.NET Core. However, the Microsoft MSDN docs suggest that developers can create their own extension methods on ISession, and they have provided code for one such pair of Set<T> and Get<T> methods that use json serialization to store any serializable type as a string. We have copy-pasted their code, and used it to create a small walkthrough that demonstrates how a DateTime instance can be stored in a session variable.

  17. Published: 31-Aug-2021
    We start by explaining the general scheme for deleting a record from a table. A foreach loop adds an anchor link to each record. The primary key (id) of each record is set as an attribute of each respective anchor link, and each anchor link also binds to a handler function in the backing class. When such a link is clicked the handler receives that id as a parameter and a C# code carries on the deletion.