Tag: <span>C#</span>

Thinking outside the box
Published 22 June 2017

Thinking outside the box

A hopefully enlightening story.

I had the need to get the latitude and longitude for UK postcodes. Knowing that another developer had recently done a lot of work doing similar things using the Google Maps API, I had a look at the code she had written. Following the Google guidelines, she had ended up adding wads of C# classes, defining the various data types that the API returns, as well as a lot of helper methods to parse the data. I had that horrible sinking feeling you get when you can see a small design requirement blow up out of all proportion.

Whilst contemplating the problem, I had an epiphany, and realised that I could solve the problem in a much simpler way, albeit with some initial effort. I thought the technique might be useful to others, but more significantly, thought that the idea of thinking outside of the box may be of interest.

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F# C#

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Published 10 November 2016

Knowing the difference between IEnumerable and IQueryable

OK, so hands up who knows the difference? Hmm, just as I thought, not many. Don’t worry about it, nor did I until just now! Rather than rambling on (as usual), I’ll just point you at a StackOverflow question where this was answered as clearly as this is likely to be answered anywhere! http://stackoverflow.com/questions/2876616/returning-ienumerablet-vs-iqueryablet By the way, if you just query your EF context and don’t explicitly convert your results, you’ll end up with an IQueryable<T>. If you use .AsEnumerable(), you’ll end up with an IEnumerable<T> (surprisingly enough).

C#

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Implementing a testable “Are you sure?” pop-up in MVVM
Published 21 March 2016

Implementing a testable “Are you sure?” pop-up in MVVM

A few years ago, I blogged about how to implement an “Are you sure” pop-up in MVVM. Well, I’ve grown up (a bit) since then, and realised that the code there wasn’t testable. I therefore take great pleasure in presenting for your delight, a testable “Are you sure” pop-up in MVVM. Aren’t I kind 🙂

Being good boys and girls, we want to write testable code, so if by some miracle we ever get around to writing unit tests, we can run them safe in the knowledge that they stand a fetid dingo’s kidney’s chance of working! One of the main issue involved here is ensuring we keep all view-related code out of the view model.

This post explains how to do it (with some pointless pictures)

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C# MVVM Design patterns

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Published 1 February 2016

Project Euler – Problem 8 Largest product in a series, or “What I learned in school today”

F# C#

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Published 13 December 2015

Why it’s sometimes good to be Lazy

I came across a situation recently in which we needed an object in the client. Due to the cost of creating this object, we didn’t want to create it when loading up the window as it might not be needed (if the user didn’t click the appropriate button), we didn’t want to store it on the window’s main object graph, but equally, we wanted to keep hold of it once it had been created. This situation is not uncommon, where you have to create a class that is expensive (in database or bandwidth terms) to create. The obvious solution to this was to have a private variable for the instance of Expensive, and a second private bool variable to indicate if the Expensive object had been created. We could check the bool before accessing the Expensive variable. Even better, we could create a property that wrapped this up. Imagine our class is wittily…

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C#

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Published 15 September 2013

Cleaning up your XAML with a grid helper class

When laying out controls on a window or user control, it is common to end up with wads of XAML that looks like this: Before you even start adding in the controls, you have quite a lot of XAML just for laying out the grid itself. Enter stage left, the GridHelper class (round of applause please). With the addition of the appropriate line to the namespace section of your window or control (depending where you save the GridHelper class): …you can reduce the XAML spaghetti above to the rather more succint: The row or column definitions are now reduced to a comma-delimited list of heights or widths. These can be absolute or star values, and can take an optional minimum value (specified after the colon). Grid splitters Grid splitters are a common feature in complex layouts, and the GridHelper class allows you to add them without writing extra XAML. All…

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C# XAML WPF

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Published 4 November 2011

Solving the anonymous types problem with tuples

One of my first posts on this blog was about the problem of using anonymous types when you want to send the data outside of your current class. At the time, the only way I knew to solve this was to create a simple class that had the structure of the anonymous type, and create one of these instead of the anonymous type. I do this regularly, although I have taken to naming such classes CustomerOverview, OrderOverview, etc, instead of CustomerTmp as I did in that blog post, as they aren’t really temporary classes at all, they are slim, flattened overviews of the class.

This approach works well, but it can have its downsides. One, as mentioned in that post, is that it is easy to end up with a proliferation of classes, many of which may only be used in one location in the code. If the classes represent lightweight views of entities in the model (such as the two examples shown above), then I don’t worry about this, as it is clear what they represent, and it’s fairly certain that I’ll end up using them somewhere else at some point.

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C# ASP.NET

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Published 16 June 2011

How to add a property to a WPF user control and have it show up in the Properties panel of the Visual Studio designer

C# WPF

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Published 10 May 2011

Implementing an “Are you sure?” pop-up in MVVM

A common scenario is to have a button on a view that is bound to a command on the viewmodel. You can also have an ABCCommandCanExecute() method on the VM that tells the view whether or not the button can be clicked.

This is all fine until you want to ask the user to confirm the action that will be performed when they click the button. For example “Are you sure you want to reformat your hard disk, dial up all the people in your contact list and reformat their hard disks, and then destroy the world?” It’s kind of rude to do this without confirmation first.

The problem is that when you use WPF binding to bind the VM’s command method to the button’s Command property, you lose control over the execution process, and so can’t inject a message box into the flow.

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C# MVVM Design patterns

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Published 15 August 2010

Passing custom and anonymous types across code boundaries

Linq is great for grabbing entity objects. The code is simple, and you end up with known objects that you can use.

But, when you want to deal with anything slightly off the beaten track, it gets a bit harder. For example, if you have a Linq query that returns an anonymous type, you can easily manipulate it in the same code block.

Here I detail an early exploration into the world of anonymous types

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Entity framework C#

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