如何防止EF Core 3.1中的列更新？ [英] How to prevent a column update in EF Core 3.1?

问题描述

我已从.Net Core 2.2升级到3.1，并且不赞成使用此功能

I upgraded from .Net Core 2.2 to 3.1 and this functionality has been deprecated

modelBuilder
.Entity<Order>()
.Property(e => e.CreationTime)
.ValueGeneratedOnAddOrUpdate()
.Metadata.IsStoreGeneratedAlways = true;

我需要EF来执行插入操作，但阻止更新。

I need EF to do the Insert but block the update.

谢谢！

推荐答案

根据废弃的属性实现：

public virtual bool IsStoreGeneratedAlways
{
    get => AfterSaveBehavior == PropertySaveBehavior.Ignore || BeforeSaveBehavior == PropertySaveBehavior.Ignore;
    set
    {
        if (value)
        {
            BeforeSaveBehavior = PropertySaveBehavior.Ignore;
            AfterSaveBehavior = PropertySaveBehavior.Ignore;
        }
        else
        {
            BeforeSaveBehavior = PropertySaveBehavior.Save;
            AfterSaveBehavior = PropertySaveBehavior.Save;
        }
    }
}

等效代码应设置 BeforeSaveBehavior 和 AfterSaveBehavior 到忽略。

自 BeforeSaveBehavior 和 AfterSaveBehavior 属性也被替换为获取 / Set 方法对，则需要引入一个临时变量来保存属性元数据。

Also since BeforeSaveBehavior and AfterSaveBehavior properties have been replaced with Get / Set method pairs, it would require introducing a temporary variable to hold the property metadata.

类似这样的东西：

var creationTime = modelBuilder
    .Entity<Order>()
    .Property(e => e.CreationTime)
    .ValueGeneratedOnAddOrUpdate()
    .Metadata;
creationTime.SetBeforeSaveBehavior(PropertySaveBehavior.Ignore);
creationTime.SetAfterSaveBehavior(PropertySaveBehavior.Ignore);

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