在ASP.NET MVC中存储跨页面的公共日期

Question

Im using a base controller & OnActionExecuting to get 'common' site data that I want to show & keep accross most page's (name, ID etc... not more than 4/5 fields)

The Method in OnActionExecuting reads the database & saves to ViewBag which Ipick up in my Views but I cant help thinking this is a waste as it needs a DB call for every OnActionExecuting.

How can consolodate these DB calls and slim down the DB access?

Answer 1

缓存存储库层中的公共数据值。

Answer 2

What I have done on a recent project is during Login I get the 'common' data which in this case was UserID, FirstName and an ImageName, I saved it in the Auth Ticket like this :

UserData = pModel.PartyId.ToString() + "|" + pModel.BusinessName + "|" + pModel.FirstName + "|" + pModel.LastName + "|" + pModel.ImageUrl + "|" + UsersRole + "|" + IsAct;//PID, BusName, FirstName, LastName, imgUrl, Role, IsAct

// Create the cookie that contains the forms authentication ticket
HttpCookie authCookie = FormsAuthentication.GetAuthCookie(UN, true);
FormsAuthenticationTicket ticket = FormsAuthentication.Decrypt(authCookie.Value);
FormsAuthenticationTicket newTicket = new FormsAuthenticationTicket(ticket.Version, ticket.Name, ticket.IssueDate, ticket.Expiration, ticket.IsPersistent, UserData);
authCookie.Value = FormsAuthentication.Encrypt(newTicket);
System.Web.HttpContext.Current.Response.Cookies.Add(authCookie);

I then retreive this Cookie when the data is needed and get the data out of it like this :

var cookie = context.Request.Cookies[FormsAuthentication.FormsCookieName];
dynamic UN = FormsAuthentication.Decrypt(cookie.Value);
string UserData = UN.UserData;//PID, BusName, FirstName, LastName, imgUrl, Role, IsAct
string[] pFields = UserData.Split('|');
string[] MyRoles = { pFields[5] };

Please Note : This is only good for static data that you know wont change during the login session & be careful what you post in this Cookie.

Don't bloat the cookie either keep the fields to a minimum, max is 4K but I aim for 500-1000 bytes.

Answer 3

Inheriting from a base controller does not mean that you have shared state across requests. Each request will result in a new controller instance.

You need to store this data in some state (cache, session, application) if you don't want to retrieve it every time. Then you can make whatever mechanism you store it in accessible from your base controller.

Then there's the disclaimer...are these trips to the database expensive? Are you going to trade minimal latency problems for memory management issues?

UPDATE:

If it is just 4-5 fields (which appear to be user specific, and like they are not going to change during a user's session), then I'd just store them in session state.

Personal preference here, but I like to have strongly typed accessors in base controllers/pages for things like this:

    protected string Name
    {
        get
        {
            if (Session["Name"] == null)
            {
                var results = GoLoadFields();                    
                return Session["Name"].ToString();
            }

            return Session["Name"].ToString();
        }

        set
        {
            Session["Name"] = value;
        }
    }

Then in all of your controllers that inherit from your base controller can just reference these properties:

myAwesomeViewModel.Name = this.Name;

The memory management disclaimer is meant to have you avoid querying the database, getting the same large result set, and shoving it in the session for each user. Before you keep anything around in memory, just make sure you're only keeping what you need and for how long you need it.

Answer 4

You can use System.Runtime.Caching.MemoryCache for this purpose.

Some examples:

• http://stevescodingblog.co.uk/net4-caching-with-mvc/
• http://msprogrammer.serviciipeweb.ro/tag/memorycache/

The cache will persist across requests until the expiration for each cache item is reached.