Package Manager Console Entity Framework 6 Migrations profile

Package Manager Console Entity Framework 6 Migrations profile

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This tutorial is about adding the following functionality to the Entity Framework Migrations CLI:

  • Execute commands against the project containing the migrations by providing the most likely -Project parameter value
  • Allow updating the database using a numeric TargetMigration (-2 = migrate to the third last migration)

Activating your Nuget_profile

When opening the Package Manager Console (PMC) in Visual Studio, the profile file is executed.

%USERPROFILE%\Documents\WindowsPowerShell\NuGet_profile.ps1

You can reload the NuGet_profile.ps1 file using . $profile in the PMC.

The following aliases allow you to install a package with just ip EntityFramework:

Set-Alias ip Install-Package
Set-Alias unip Uninstall-Package

Provide most likely -Project parameter

There is (unfortunately) no way to configure the “Default project” in the PMC. This workaround creates a Verb-RealNoun for each existing cmdlet and adds a short alias to these commands. Which project contains the migrations is by convention, as determined by $isLikelyDbContextProject.

# Execute commands against first ProjectName to end with one of these:
$isLikelyDbContextProject = ".DataAccess", ".Back"

function Get-DbContextProject {
	return Get-Project -All |
		Where-Object {
			if ($_.ProjectName.LastIndexOf(".") -gt -1) {
				return $isLikelyDbContextProject -match $_.ProjectName.Substring($_.ProjectName.LastIndexOf("."))
			} else {
				return $false
			}
		} | Select -First 1
}

function Add-RealMigration($name = "test") {
	$project = Get-DbContextProject
	Add-Migration $name -Project $project.ProjectName
}

Set-Alias am Add-RealMigration

# Usage
am AddedBlogTable

The entire list of aliases:

Set-Alias em Enable-RealMigrations
Set-Alias am Add-RealMigration
Set-Alias ad Add-RealMigration
Set-Alias ud Update-RealDatabase
Set-Alias udv Update-RealDatabaseVerbosely
Set-Alias gam Get-AppliedMigrations
Set-Alias lm List-Migrations # List last $listMigrationsCount
Set-Alias lam List-AllMigrations

Updating the database using a numeric TargetMigration

Easily go back to a specific migration using ud -1 instead of

Update-Database -TargetMigration:SecondLastMigrationName

Usage

# List last 5 migrations:
# (aliased as List-Migrations or lm)
$ Get-MigrationsTable | Select-Object -First 5 | Format-Table -AutoSize

Index Name                   Created          FullName  
----- ----                   -------          --------  
0     MatchShouldBePlayed    12/24/2016 16:25 201612241625590_MatchShouldBePlayed.cs  
-1    MatchFormationComment  12/24/2016 14:34 201612241434105_MatchFormationComment.cs  
-2    UserPasswordResetLinks 10/23/2016 18:53 201610231853333_UserPasswordResetLinks.cs  
-3    ClubManagerTypes       09/23/2016 20:46 201609232046188_ClubManagerTypes.cs  
-4    BlockMatchField        08/18/2016 21:40 201608182140266_BlockMatchField.cs  

# Update database to ClubManagerTypes
$ Update-RealDatabase -3 # Alias: ud -3

# Update database to latest migration (MatchShouldBePlayed)
$ Update-RealDatabase 0 # Alias: ud

Attention:
This completely ignores whatever may be the last migration that was applied to the database. Having Update-RealDatabase -1 go back to the “last applied migration - 1” instead of the current implementation “go to the second last migration added to the project”, would require analysing Get-Migrations, which would make the whole thing considerably slower. (FileSystem vs Sql query)

Source

function Get-MigrationsTable {
	$project = Get-DbContextProject
	$projectPath = Split-Path -Path $project.FullName

	$migrations = Get-ChildItem "$projectPath\Migrations" |
		Where-Object { Test-MigrationName $_.Name } |
		Sort-Object Name -Descending

	return $migrations | ForEach-Object -Begin {$idx = 0} -Process {
		$withoutExt = $_.Name.Substring(0, $_.Name.LastIndexOf("."))
		$migrationName = $withoutExt.Substring($withoutExt.IndexOf("_") + 1)
		$dateStr = $_.Name.Substring(0, $_.Name.IndexOf("_"))
		$date = [DateTime]::ParseExact($dateStr.Substring(0, 12), "yyyyMMddHHmm", $null)

		$_ | Select-Object -Property `
			@{l='Index';e={"$idx"}}, `
			@{l='Name'; e={$migrationName}}, `
			@{l='Created'; e={$date.ToString("g")}}, `
			@{l='FullName'; e={$_.Name}}

		$idx -= 1
	}
}

function Update-RealDatabase([int]$targetMigration = 0) {
	$project = Get-DbContextProject
	if ($targetMigration -eq 0) {
		# Default: Update to latest migration
		Update-Database -Project $project.ProjectName
	} else {
		# With negative number: Go to x last created migration
		$migration = Get-MigrationsTable | Where-Object {$_.Index -eq $targetMigration}
		echo "Migrating to last migration $targetMigration => $($migration.name)"
		Update-Database -Project $project.ProjectName -TargetMigration $migration.name
	}
}

function Test-MigrationName($fileName) {
	return $fileName -match "^(\d[^.]+)\.(cs|vb)$"
}

Open the Package Manager Console in Visual Studio

Menu: Tools > NuGet Package Manager > Package Manager Console
Shortcut: Alt + T, N, O
Custom shortcut: View.PackageManagerConsole


Stuff that came into being during the making of this post
Updates
  • 28 March 2018 : Fix for Visual Studio 2017
Tags: net powershell