Linq用另一个值替换空/空值 [英] Linq replace null/empty value with another value

问题描述

在sql server中，我创建了一些视图，可以在其中检查空值，如果需要，可以将其替换为默认值(即ISNULL(PrimaryPhone，'No Primary#')AS PrimaryPhone.我在asp中使用了很多视图.网络表单应用程序，但是我现在正在学习MVC 4，并希望从头开始.

In sql server I create views where I can check for null values and replace them with a default if I want (i.e. ISNULL(PrimaryPhone, 'No Primary #') AS PrimaryPhone. I used a lot of views in my asp.net web forms application, but I am now learning MVC 4 and want to start out right.

我为我的客户表设置了模型，控制器和视图.我希望能够将null/empty值替换为("Not Entered")或类似的值. 我相信这需要在控制器中进行，如果我错了，请纠正我.

I have a model, controller and view set up for my client table. I would like to be able to replace null/empty values with ("Not Entered") or something like that. I believe this needs to go in the controller, please correct me if I'm wrong.

我看到了一个使用hasvalue的示例，但无法通过智能感知使用.

I saw an example that uses hasvalue, but it is not available through intellisense.

如何在模型中不使用DefaultValue的情况下替换空/空值?

How would I replace empty/null values without using DefaultValue in my model?

谢谢

var result = db.Clients.Select(x => new
        {
            CustomerID = x.CustomerID,
            UserID = x.UserID,
            FullName = x.FullName,
            EmailAdd = x.emailadd.DefaultIfEmpty("No Email"),....

推荐答案

您可以使用

You can use the ?? operator to set a default value when something is null:

var result = db.Clients.Select(x => new
        {
            CustomerID = x.CustomerID,
            UserID = x.UserID,
            FullName = x.FullName,
            EmailAdd = x.emailadd ?? "No Email", ...

如果您需要更多控制，例如检查null和empty，还可以使用

If you need more control, for example checking for both null and empty, you can also use the ?: operator (also known as the "conditional operator" or "ternary operator"):

var result = db.Clients.Select(x => new
        {
            CustomerID = x.CustomerID,
            UserID = x.UserID,
            FullName = x.FullName,
            EmailAdd = string.IsNullOrEmpty(x.emailadd) ? "No Email" : x.emailadd, ...

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