Custom type mapping about efcorepowertools HOT 17 CLOSED

Create a proper, surrogate primary key?

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Anything goes, and the tool is open source and welcomes contributions!

Could you show an example of what a class with a Enum would look like before and after this?

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From @mbeckenbach on February 4, 2018 7:57

Hi @ErikEJ, good to hear that.

A typical example for my use case would be like this. You have a custom enum in some folder/namespace and a generated class like the ones below.

namespace EFCoreTest.Enums
{
    public enum Categories
    {
        SomeCategory = 0,
        AnotherCategory = 1,
        MoreCategories = 2
    }
}

namespace EFCoreTest.Models
{
    public partial class Post
    {
        public int Id { get; set; }
        public string Text { get; set; }
        public int Category { get; set; }
    }
}

After transformation the class would simply look like this:

public partial class Post
    {
        public int Id { get; set; }
        public string Text { get; set; }
        public Enums.Categories Category { get; set; }
    }

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OK. since I just get the generated files, maybe it would be better with

 "TypeMappings": [
    { "Class:"Post", "Property":"Category", "Type": "Enums.Categories" }
  ]

Do a PR, perhaps?

https://github.com/ErikEJ/SqlCeToolbox/blob/master/src/GUI/ReverseEngineer20/EFCoreReverseEngineer.cs#L130

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From @mbeckenbach on February 6, 2018 6:54

I have never edited a vs extension. But i'll try at weekend. :-)
Thanks for the hint on the line.

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Great, let me know if you hit any stumbling blocks! (It is a bit more involved than a standard Nuget library)

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My Handlebars library handles this scenario now. See the project ReadMe for an example of adding an enum transformation and mapping it with a partial method.

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@tonysneed Thanks. I assume that this will require changes to the users product code, and does not apply to EF Core Power Tools??

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There are many options to do this, while preserving the modifications when reverse engineering is run a second time:

For the Enum, create at MyTypeEnum property in the partial entity class.

For special translations, use the OnModelCreating partial method to modify the model with Value Conversions https://docs.microsoft.com/en-us/ef/core/modeling/value-conversions

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Thank you for creating this tool. I was looking for Enum mapping as well and came across this post.

I tried adding the following to efpt.renaming.json but it didn't have any effect:
"TypeMappings": [
{ "Class:"Post", "Property":"Category", "Type": "Enums.Categories" }
]

Could you please clarify what's the recommended way of mapping Enums with EF Core Power Tools? Thanks!

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@AlexVPerl create a NonMapped enum property in a partial class

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@ErikEJ thank you for prompt reply. Do you mean an Enum wrapper property that would set/get persisted numeric value?

If so, I was trying to avoid that since then EF will do in memory filtering when Enum is mentioned in the LINQ query.

Above, there is a mention of using OnModelCreating partial method with Value Conversions - this would be ideal. But it doesn't seem possible since all columns will be mapped in the auto generated class, and EF won't allow mapping 2 properties to single column. Having a way to ignore a column when using Rev. Eng. auto generation would make it possible to manually do Value Conversions for it. Or is there another way?

Thanks.

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At the moment this is not supported. Happy to receive ideas or a PR for implementation.

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@ErikEJ thank you for prompt reply. Do you mean an Enum wrapper property that would set/get persisted numeric value?

If so, I was trying to avoid that since then EF will do in memory filtering when Enum is mentioned in the LINQ query.

Above, there is a mention of using OnModelCreating partial method with Value Conversions - this would be ideal. But it doesn't seem possible since all columns will be mapped in the auto generated class, and EF won't allow mapping 2 properties to single column. Having a way to ignore a column when using Rev. Eng. auto generation would make it possible to manually do Value Conversions for it. Or is there another way?

Thanks.

@AlexVPerl , @ErikEJ - I am also looking for a way to Map an enum value to a string. If I understand correctly, the one thing blocking @AlexVPerl's suggested solution was the ability to ignore a column. Well, it seems that this feature was recently added via a pull request: #572

I'm going to give that a go, but leaving this train of thought here for others to help save them some time. I'll make another note if I have anything interesting to report

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I'm going to give that a go, but leaving this train of thought here for others to help save them some time. I'll make another note if I have anything interesting to report

• Well, for me, good news and bad news... it looks like ignoring a column is new baked right into the UI! (Nice feature@ErikEJ)
• In my case, it seems I can not ignore the column I want to transform into an Enum because it part of the primary key... so, I will find a different approach

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Custom enum mapping is now available with EF Core 7 and T4 templates

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