Simon Online


Flutter Widget Testing

I’m sure I don’t have to tell you how important automated tests are to the software development process. Even if they didn’t have other advantages I’d write tests just so I could have that sense of security when changing things in an application. Most every framework and language has some sort of testing ability built into it and Flutter is no different. However the documentation for widget testing in flutter is pretty poor. This post should get you over some of the gotchas I faced.

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Allow hosted agents through firewall

I have an on-premise (well in a third party data center but close enough) database which I’d like to update via a build in a hosted agent on Azure. We’ve done this before in Jenkins by just allowing a specific IP address through the firewall. However we’re in the process of moving to DevOps for this build. Unfortunately, the hosted build agents don’t have entirely predictable IP addresses. Every week Microsoft publishes a list of all the IP addresses in Azure. It is a huge json document and for our region (Central Canada) there are about 40 IP addresses ranges the build agent could be in. We want an automated way to update our firewall rules based on this list.

To do so we make use of the Azure Powershell extensions. The commandlet Get-AzNetworkServiceTag is an API based way to get the IP ranges. You can then pass that directly into the firewall rules like so

$addrs = ((Get-AzNetworkServiceTag -Location canadacentral).Values|Where-Object { $_.Name -eq "AzureCloud.canadacentral" }).Properties.AddressPrefixes
Set-NetFirewallRule -DisplayName "Allow SQL 1433 Inbound" -RemoteAddress $addrs

Running this once a week lets us keep the firewall up to date with the hosted agent ranges.



I really dislike database queries which are slow for no apparent reason. I ran into one of those today. It queries over a few thousands of well indexed rows and returned a handful, perhaps 3, records. Time to do this? 33 seconds. Well that’s no good for anybody. Digging into the query I found that it actually used a UNION to join 3 sets of similar data together. I go by the rule of thumb that SQL operations which treat data as sets and do things with that in mind are efficient. I’m not sure where I read that but it has stuck with me over the years. What it suggests is that you should avoid doing things like looping over rows or calling functions on masses of data.

As it turns out there are actually two different UNION operators in SQL Server: UNION and UNION ALL. They differ in how they handle duplicate entries. UNION will check each entry to ensure that it exists in the output only one time.

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Machine Learning for Boring Applications

C# Advent

This post is one among many which is part of 2019’s C# Advent. There are a ton of really great posts this year and some new bloggers to discover. I’d strongly encourage you to check it out.

If you read at all about the myriad of applications for machine learning you’ll find that there are a lot of people out there building really cool stuff. Cars which drive themselves. Things which write tweets based on an AI’s interpretation of thousands of tweets about venture capitalists. Unfortunately I, like a lot of developers, earn our bread and butter by writing what is mostly boring forms over data applications. This is a space in which there is 0 application for machine learning. Or is there?

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Bulk Load and Merge Pattern

The more years you spend programming the more you run into situations you’ve run into before. Situations you now know, instinctively, how to address. I suppose this is “experience” and is what I’m paid the medium dollars for. One such problem I’ve solved at least a dozen times over the years is updating a bunch of data in a database from an external source. This, as it turns out, can be a great source of poor performance if you don’t know how to address it. Let’s dig into my approach.

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Debug PHP Inside A Container with VSCode

Sometimes good things happen to bad people and sometimes bad things happen to good people. I’ll let you decide which one me developing a PHP application is. Maybe it is a bit of a mixture. This particular PHP app was a bit long in the tooth (what PHP app isn’t) and ran on full VMs. My first operation was was to get it running inside a docker container because I couldn’t be sure that my Windows development environment would be representative of production, then I wanted to be able to debug it. This is the story of how to do that.

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Azure DevOps Terraform Trouble

I’m a big fan of Azure DevOps and also of Terraform. I use the Terraform tasks to run deployments of infrastructure in a DevOps pipeline. Today my old reliable build broke because of a change to the version of Terraform.

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Unable to cast object of type Microsoft.XrmSdk.Entity

You’ll likely encounter early bound types when developing workflows, plugins or anything else which calls the Dynamics 365 SDK. These are basically generated classes which come from Dynamics. You can generate them using the CrmSvcUtil.exe. If you’ve ever done anything with T4 templates you can think of them as that or a really poor substitute for F# type providers.

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Running MiniKube on an Azure VM

MiniKube is a Kubernetes distribution designed to make running a single node Kubernetes cluster easy for local development. However MiniKube relies on docker which relies on you having a Professional version of Windows on your laptop. If you don’t have that then it is really easy to stand up an Azure VM which can run MiniKube.

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Add records to Dynamics 365 from PowerShell

Dynamics 365 is a low code solution for a variety of different businesses offered by Microsoft. It is a fully hosted solution which means that you don’t really get access to the underlying database. That’s a good thing (less to manage) but also a bad thing (hard to work with for power users).

In this post we’ll look at how to manipulate records in the CRM using some powershell.

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