将EF迁移整合到新的InitialCreate中 [英] Consolidating EF migrations into new InitialCreate
问题描述
我已经使用EF迁移已有一段时间了，并且我的项目中有100多个迁移文件。在进行下一步之前，我想将它们合并为一个迁移-即，我想用一个考虑了所有后续更改的新版本替换现有的InitialCreate迁移，以便随后删除所有其他迁移文件。
I have been using EF migrations for some time now and have more than 100 migration files in my project. I would like to consolidate these into a single migration before moving forward - ie I want to replace the existing InitialCreate migration with a new version that takes all my subsequent changes into account so I can then delete all the other migration files.
如果我不担心丢失数据库中的所有数据，我会很容易地做到这一点，但是我确实如此。
I do this very easily if I am not concerned with losing all the data in the DB, but I am.
如何我可以做到这一点，同时保持所有数据完整无缺，还可以通过仅运行Update-Database（我相信使用朱莉·勒曼（Julie Lerman）概述的方法）？
How can I achieve this whilst keeping all data intact and also retaining the ability to recreate the database from scratch (without data) by just running Update-Database (which I believe is not possible using the approach outlined by Julie Lerman)?
推荐答案
请考虑阅读Rick Strahl的这篇不错的文章：
https：// weblo g.west-wind.com/posts/2016/jan/13/reset-entity-framework-migrations-a-clean-slate
Consider reading this nice article from Rick Strahl : https://weblog.west-wind.com/posts/2016/jan/13/resetting-entity-framework-migrations-to-a-clean-slate
基本上，该解决方案不是简单的，它不仅需要将所有迁移重置为一个
，还需要更多，因为您有两种情况需要适合一个迁移类：
Basically the solution is not trivial and needs more than just reseting all the migrations into one because you have two scenarios that needs to fit in ONE migration class:
- 创建一个新数据库=>迁移类应该包含每个表的创建
- 我的数据库已经是最新的=>我需要一个空的迁移类
解决方案：
该过程的想法基本上是这样的：数据库和EF模式是最新的，并且与您想要它，所以我们将删除现有的迁移并创建一个新的初始迁移。
Solution: The idea of this process is basically this: The database and the EF schema are up to date and just the way you want it, so we are going to remove the existing migrations and create a new initial migration.
总而言之，执行此操作的步骤是：
In summary, the steps to do this are:
- 从数据库中删除_MigrationHistory表
- 删除项目的Migrations文件夹中的各个迁移文件
- 在Packa中启用迁移ge Manager控制台
- 在PMC中添加初始迁移
- 在初始迁移中注释掉Up方法内部的代码
- PMC中的更新数据库（除了创建迁移
条目外什么都不做）在Initial方法中删除注释您现在基本上已经将
的架构重置为最新版本。 - 注释注释完的迁移已在所需数据库上执行后，取消注释迁移代码
- Remove the _MigrationHistory table from the Database
- Remove the individual migration files in your project's Migrations folder
- Enable-Migrations in Package Manager Console
- Add-migration Initial in PMC
- Comment out the code inside of the Up method in the Initial Migration
- Update-database in PMC (does nothing but creates Migration Entry) Remove comments in the Initial method You've now essentially reset the schema to the latest version.
- once the commented out migration has been executed on the desired database, uncomment the migration code
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