嵌套属性的 SetModifiedProperty

Question

如何为嵌套属性设置 SetModifiedProperty？换句话说，我有一个实体作者，其实体有一个书籍集合，我只需要更改一个书名。

    var existingAuthor = authors.FirstOrDefault(x => x.Id.Equals(authorId));
    var bestSellerBook = existingAuthor.Books.FirstOrDefault(x=> x.Id.Equals(bookId));
    existingAuthor.Name = "xxxxxxx";
    bestSellerBook.Name = "xxxxxxxxxxx";
    context.Authors.Attach(existingAuthor);  
    context.ObjectStateManager.GetObjectStateEntry(existingAuthor).SetModifiedProperty("Name");
    context.SaveChanges();

有什么建议吗？

Answer 1

您必须获取持有已更改属性的实体的对象状态条目=在您的情况下它必须是书：

var existingAuthor = authors.FirstOrDefault(x => x.Id.Equals(authorId));
var bestSellerBook = existingAuthor.Books.FirstOrDefault(x=> x.Id.Equals(bookId));
bestSellerBook.Name = "xxxxxxxxxxx";
context.Authors.Attach(existingAuthor);  
context.ObjectStateManager.GetObjectStateEntry(bestSellerBook).SetModifiedProperty("Name");
context.SaveChanges();