我用这个:

实体:

public class Thing 
{
    [Key]
    public int Id { get; set; }
    public string Info { get; set; }
    public string OtherStuff { get; set; }
}

数据库上下文：

public class MyDataContext : DbContext
{
    public DbSet<Thing > Things { get; set; }
}

访问器代码:

MyDataContext ctx = new MyDataContext();

// FIRST create a blank object
Thing thing = ctx.Things.Create();

// SECOND set the ID
thing.Id = id;

// THIRD attach the thing (id is not marked as modified)
db.Things.Attach(thing); 

// FOURTH set the fields you want updated.
thing.OtherStuff = "only want this field updated.";

// FIFTH save that thing
db.SaveChanges();

结合几项建议，我提出如下:

    async Task<bool> UpdateDbEntryAsync<T>(T entity, params Expression<Func<T, object>>[] properties) where T : class
    {
        try
        {
            var entry = db.Entry(entity);
            db.Set<T>().Attach(entity);
            foreach (var property in properties)
                entry.Property(property).IsModified = true;
            await db.SaveChangesAsync();
            return true;
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine("UpdateDbEntryAsync exception: " + ex.Message);
            return false;
        } 
    }

被

UpdateDbEntryAsync(dbc, d => d.Property1);//, d => d.Property2, d => d.Property3, etc. etc.);

或通过

await UpdateDbEntryAsync(dbc, d => d.Property1);

或通过

bool b = UpdateDbEntryAsync(dbc, d => d.Property1).Result;

我用这个:

实体:

public class Thing 
{
    [Key]
    public int Id { get; set; }
    public string Info { get; set; }
    public string OtherStuff { get; set; }
}

数据库上下文：

public class MyDataContext : DbContext
{
    public DbSet<Thing > Things { get; set; }
}

访问器代码:

MyDataContext ctx = new MyDataContext();

// FIRST create a blank object
Thing thing = ctx.Things.Create();

// SECOND set the ID
thing.Id = id;

// THIRD attach the thing (id is not marked as modified)
db.Things.Attach(thing); 

// FOURTH set the fields you want updated.
thing.OtherStuff = "only want this field updated.";

// FIFTH save that thing
db.SaveChanges();

Ladislav的答案更新为使用DbContext(在EF 4.1中引入):

public void ChangePassword(int userId, string password)
{
    var user = new User() { Id = userId, Password = password };
    using (var db = new MyEfContextName())
    {
        db.Users.Attach(user);
        db.Entry(user).Property(x => x.Password).IsModified = true;
        db.SaveChanges();
    }
}

我使用valueinjector nuget注入绑定模型到数据库实体使用如下:

public async Task<IHttpActionResult> Add(CustomBindingModel model)
{
   var entity= await db.MyEntities.FindAsync(model.Id);
   if (entity== null) return NotFound();

   entity.InjectFrom<NoNullsInjection>(model);

   await db.SaveChangesAsync();
   return Ok();
}

注意使用自定义约定，如果属性在服务器上为空，则不更新属性。

ValueInjecter v3 +

public class NoNullsInjection : LoopInjection
{
    protected override void SetValue(object source, object target, PropertyInfo sp, PropertyInfo tp)
    {
        if (sp.GetValue(source) == null) return;
        base.SetValue(source, target, sp, tp);
    }
}

用法:

target.InjectFrom<NoNullsInjection>(source);

值注入器V2

查找这个答案

警告

您将不知道该属性是被故意清除为null还是它只是没有任何值。换句话说，属性值只能被替换为另一个值，而不能被清除。

I know this is an old thread but I was also looking for a similar solution and decided to go with the solution @Doku-so provided. I'm commenting to answer the question asked by @Imran Rizvi , I followed @Doku-so link that shows a similar implementation. @Imran Rizvi's question was that he was getting an error using the provided solution 'Cannot convert Lambda expression to Type 'Expression> [] ' because it is not a delegate type'. I wanted to offer a small modification I made to @Doku-so's solution that fixes this error in case anyone else comes across this post and decides to use @Doku-so's solution.

问题是Update方法中的第二个参数，

public int Update(T entity, Expression<Func<T, object>>[] properties). 

使用提供的语法调用此方法…

Update(Model, d=>d.Name, d=>d.SecondProperty, d=>d.AndSoOn); 

你必须在第二个参数前面加上'params'关键字。

public int Update(T entity, params Expression<Func<T, object>>[] properties)

或者如果你不想改变方法签名，那么要调用Update方法，你需要添加'new'关键字，指定数组的大小，然后最后使用集合对象初始化语法来更新每个属性，如下所示。

Update(Model, new Expression<Func<T, object>>[3] { d=>d.Name }, { d=>d.SecondProperty }, { d=>d.AndSoOn });

在@Doku-so的例子中，他指定了一个表达式数组，所以你必须在数组中传递属性来更新，因为数组你还必须指定数组的大小。为了避免这种情况，您还可以更改表达式参数，使用IEnumerable而不是数组。

下面是@Doku-so解决方案的实现。

public int Update<TEntity>(LcmsEntities dataContext, DbEntityEntry<TEntity> entityEntry, params Expression<Func<TEntity, object>>[] properties)
     where TEntity: class
    {
        entityEntry.State = System.Data.Entity.EntityState.Unchanged;

        properties.ToList()
            .ForEach((property) =>
            {
                var propertyName = string.Empty;
                var bodyExpression = property.Body;
                if (bodyExpression.NodeType == ExpressionType.Convert
                    && bodyExpression is UnaryExpression)
                {
                    Expression operand = ((UnaryExpression)property.Body).Operand;
                    propertyName = ((MemberExpression)operand).Member.Name;
                }
                else
                {
                    propertyName = System.Web.Mvc.ExpressionHelper.GetExpressionText(property);
                }

                entityEntry.Property(propertyName).IsModified = true;
            });

        dataContext.Configuration.ValidateOnSaveEnabled = false;

        return dataContext.SaveChanges();
    }

用法:

this.Update<Contact>(context, context.Entry(modifiedContact), c => c.Active, c => c.ContactTypeId);

@Doku-so提供了一种使用泛型的很酷的方法，我用这个概念来解决我的问题，但你不能使用@Doku-so的解决方案，在这篇文章和链接的帖子中，都没有人回答使用错误的问题。