I have 2 webforms with 1 ListBox Control on each of them.
How do I access the Listbox that's located on webformA from webformB?
For example I wish to declare something like this string name = ListBoxWebformA.SelectedValue.ToString(); on WebFormB, so that I can work with that value in the code of WebFormB.
The ListBox on WebFormA lists several names.
When I select a name from the listbox and press the OK button I call Response.Redirect("~/WebFormB.aspx");
So from WebFormB I wish to access this "name" by putting the selected value into a string.
Based on your edit, the easiest (possibly best) way to go about doing this will not be to try to maintain a stateful instance of webformA during the request to webformB. Once the user is redirected, assume that webformA is gone.
Instead, when you're about to perform the Response.Redirect() to webformB, include in some way the value from webformA that you wish to pass along. The easiest way to do this will be on the query string. Something like:
Response.Redirect(string.Format("~/WebFormB.aspx?name={0}", HttpUtility.UrlEncode(ListBoxWebformA.SelectedValue.ToString())));
Then, in webformB you can access the value:
string name = Request.QueryString["name"];
Note that you'll want to do some error checking, etc. Make sure the value is actually selected before appending it to the redirect URL on webformA, make sure Request.QueryString["name"] contains a value before using it in webformB, etc.
But the idea in general is to pass that value along, by query string or POST value or Session value or some other more stateful means, when redirecting from one form to the other.
I guess you have to resort to either passing the value from A to B in the query string or storing the value in Session and reading afterwards.
So would be a
Response.Redirect(string.Format("~/WebFormB.aspx?YourVariable={0}",HttpUtility.UrlEncode(ListBoxWebformA.SelectedValue));
and you can read it in Form B like
Request.QueryString["YourVariable"]
If the values are not sensitive this approach above would be the best.
If they are... To store in Session:
Session["YourVariable"] = ListBoxWebformA.SelectedValue
And to read...
if (Session["YourVariable"] != null) {
var listAValue = Session["YourVariable"].ToString()
}
Related
Im trying working on a web app project and trying to figure out how to display my answer on the second web page.
I have put a a text box on my first webpage and have corrected the coding of my application as I have received the correct answers in the textbox after I have debugged it.
Ideally I want to remove this textbox and want my answers which I managed to display on my textbox displayed on a label in the next webpage. Here is the calculation part of my code;
var cost = ((int)duration.TotalMinutes) * 0.35m;
txtCost.Text = cost.ToString("c");
I'd like to make my answer appear in my second webpage and not have it displayed in the first. I have tried using Session["Cost"] = cost; on the button click event handler of the first webpage double cost = (double)(Session["Cost"]);
lblDisplay.Text = cost.ToString("c");
and this on the second webpage but every time I Debug it and run I always get $0.00 displayed on my label. Can someone help me fix this?
Sharing value between two views in MVC application, try following
// To save into the Cache
System.Web.HttpContext.Current.Cache["CostKey"] = cost;
// To retrieve Cache Value
var cachedValue = System.Web.HttpContext.Current.Cache["CostKey"] as double;
For Session State, have a look at this link
In ASP.NET WebForms application, you can pass data around in various ways:
Cache
See the Learning Curve answer for examples.
However, the object put in the cache is not guaranteed to be found again if the server experiences memory shortage or alike. The ASP.NET manages the cache and evicts objects on its own to maintain memory availability. This is in contrast with ApplicationState and SessionState where the objects are kept until they are removed manually, or the Application ends or Session expires.
Session and Application states
You can put any object in the SessionState object and retrieve it elsewhere in your code. However, you need to cast it appropriately as the SessionState accepts object-s. E.g. if you store a number, when you retrieving it, you must do the casting yourself, just as you already did it.
The reason it doesn't work, is perhaps you're trying to retrieve it from within another user's SessionState. Yes, the SessionState is a per-user structure. If you need to add the value as from one device and use it on another, use ApplicationState:
Application["cost"] = cost;
Redirecting Response
Using this technique, you could force the browser to request another page from the server and specify the full query string, including the variables you need. E.g. :
var destination = Server.UrlEncode("/someOtherPage.aspx?cost=34.65");
Response.Redirect(destination);
As an alternative, you can use Server.Transfer("someOtherPage.aspx") to save the roundtrip. However, in that case, the browser doesn't change the address in the address bar so the user is misled that she browses one page, but in fact, it is the someOtherPage.aspx.
I have a drop down list which retrieves values from a session I declare as follows.
var autoData = autoRetriever.GetAutoDataByUserId(user.Id);
Session["AutoData"] = autoData;
I then use autoData to populate my drop down list with a “Name” and a int “Value” as indexed in the database. Name and value are both part of my table in the database.
What I am trying to do now is once a user selects from the drop down I am passing the value (e.g 0,1,2,3,n) the id on the db table to a method. OnSelected changed I want to use this value and retrieve another column “Path” from my session (autoData). Namely the path that is associated with the id. Once I have the correct “Path” associated with this value I can move forward with it.
With my OnSelectedIndexChanged method I then have the following. This string selectedAuto contains my value (0,1,2,3,n)
string selectedAuto = AutoDropDown.SelectedValue;
Does anyone have any advice on how I could move forward with this? If I have not explained enough please let me know and I will delve deeper into it.
As #David mentioned yes correct i am trying to use that value to identify that record. That is the part i am finding tricky. How can i retrieve that "Path" based on the value i select.
In a C# MVC3 solution I'm passing the request.form as a string to a webservice (I understand it would be much better to break it down and populate a model but it's compromised with old code and mainly with time) and at a step the string is huge due to many options and failed in the service.
Actually I won't need all of this options, which are basically several dropdownlists from which I just need one of them, so I'm trying to figure out how to change the request.form in order to remove the redundant ones and just keep the one selected.
To put this into context, this should be part of the string (just a middle chunk of it)
NG2BEF01-16344-181-E-16344-0-SHW_SHR*16344*MAT*1*2500*1600=0&NG2BEF01-16344-181-E-16344-0-SHW_SHR*16344*MAT*2*5500*6200=0&NG2BEF01-16344-181-E-16344-0-SHW_39S*16344*EVE*1*1500*0=2
And I would like to remove all of the options appart from (in this portion) the last one wich =2. This 0's and the 2 come from a dropdown list which name is all the rest of the parameter (ie NG2BEF01-16344-181-E-16344-0-SHW_39S*16344*EVE*1*1500*0) although it may be completely different, not always follow this pattern.
Is there any way I can get rid of the dropdown lists I leave to 0 in the request.form before submitting (or even in the controller would be acceptable)?
You could filter out values that you don't want to keep:
var values = HttpUtility.ParseQueryString("NG2BEF01-16344-181-E-16344-0-SHW_SHR*16344*MAT*1*2500*1600=0&NG2BEF01-16344-181-E-16344-0-SHW_SHR*16344*MAT*2*5500*6200=0&NG2BEF01-16344-181-E-16344-0-SHW_39S*16344*EVE*1*1500*0=2");
string result = string.Join("&", values.Cast<string>().Where(key => values[key] == "2").Select(key => string.Format("{0}={1}", key, HttpUtility.UrlEncode(values[key]))));
// The result variable will contain only kvps where the value equals 2
Is there a way to pass a parameter to a controller without putting it on the URL?
For example,
http://www.winepassionate.com/p/19/wine-chianti-docg-la-moto
has the value 19 on the URL. If you actually change that value to another, the page displays a different record even it the page name remains the same.
So I would like to NOT pass the ID on the URL but still be able to pass that to the Controller.
What's the recommended way to do so?
You can do a post and send it as a form parameter. I do not recommend this. Posts should be for requests that modify data. In this case you're most likely looking just to get that data. The fact that the id is in the URL is a good thing (see the Stack Overflow URLs for reference). If you really don't want the user to be able to modify it (I hope it's not because you think this makes it more secure, because it doesn't), you could do some simple encryption on it to make it more difficult to guess/produce a valid ID.
Using TempData, as some other suggest, is not a robust solution. It won't work for links on a page, just a GET after POST, and then only once since TempData is deleted after the next request.
Well, you have a couple of options:
Is this a form post? If so, then you can simply add a specific key value pair to your form when you submit it and then data will be passed along.
Is the URL unique to that resource? i.e. Does "Wine-chianti-docg-la-moto" exist as a unique representation of the number 19 in a database somewhere? If so, then you can simply do a lookup of that route component in your database to retrieve the value you need (or push that logic all the way down to the database).
Is that a value that is not expected to change a bunch? You can set that value in Session or in a cookie that would be persisted across pages and then pull it from the respective collection.
Are you redirecting to this page from another request on your server? If so, then you can use TempData to store this temporary value. However, I would recommend against this approach, as it is very transient and not good practice imo.
Lastly, you can obscure the value on the URL if you dont want it to be easily user editable. Encrypt it with some algorithm, and then decrypt it on the destination page. The user will be unlikely to be able to alter the ID by typing in a different value in the URL.
If the page is a GET, and you are following the PRG like you should be (Post-Redirect-Get) then you can use TempData["dataName"] = value; in your [HttpPost] controller and then consume it in your [HttpGet] method. It really depends on how the page is being called.
However, there is nothing wrong in letting the user change that number if it is not security related, and is common practice to show non-vital information in the url like that.
You should use TempData in this case. A good read on this can be found on this blog.
TempData allows you to store a value temporarily between requests and is, by default, erased after being accessed.
// TempData samplepublic ActionResult Featured(){ var featuredProduct = new Product { Name = "Assorted Cupcakes", Description = "Delectable vanilla and chocolate cupcakes", CreationDate = DateTime.Today, ExpirationDate = DateTime.Today.AddDays(7), ImageName = "cupcakes.jpg", Price = 5.99M, QtyOnHand = 12 };
I'm creating a database where users can enter some Error Reports and we can view them. I'm making these database with C# in the ASP MVC 3 .NET framework (as the tags imply). Each Error Report has a unique ID, dubbed ReportId, thus none of them are stored under the same Id. However, whenever a User creates a new Error, I pass their User Name and store it in with the rest of the report (I use User.Identity.Name.ToString() to get their name and store it as a string). I know how to get a single item from the data using a lambda expression, like so:
db.DBSetName.Single(g => g.Name == genre)
The above code is based on an MVC 3 tutorial (The Movie Store one) provided by ASP. This was how they taught me how to do it.
My major question is: is there a member function like the .Single one that will parse through the whole database and only output database entries whose stored User Name matches that of the currently logged in user's? Then, I can use this to restrict User's to being only able to edit their own entries, since only their entries would be passed to the User's View.
What would be the best way to implement this? Since the ReportId will not be changed, a new data structure can be created to store the user's Errors and passed through to the Index (or Home) View of that particular controller. From there they should be able to click any edit link, which will pass the stored ReportId back to the Edit Action of this particular controller, which can then search the entire database for it. Am I right in assuming this would work? And would this be ideal, given that the other items in the database are NOT passed through to the Index in this method, meaning the User does not have access to the other items' ReportId's, which the user needs to pass into the Edit Action for it to work? If this is ideal, this is the method that requires me to know how to parse through a database and grab every element that fits a particular description (stored User Name matches User's current User Name).
Or would a better approach be to pass the whole database to the Index View and only output the database entries that have User Name values that match the current logged in user's? I guess this could be done in a foreach loop with a nested if loop, like so:
#foreach(var item in db.Reports)
{
if(item.UserName == User.Identity.Name.ToString())
{
...code to output table...
}
}
But this passes the whole database which gives the user a lot more info than they need. It also gives them potential access to info I don't want them to have. However, I don't have to make a new data structure or database, which should lower server memory usage and fetch time, right? Or are databases passed by copy? If so, this method seems kinda dumb. However, I don't know if the first method would fracture the database potentially, this one certainly would not. Also don't remember if I NEED an else statement in C#, I'm more familiar with C++, where you don't need one and you also don't need {}'s for single line if's, if I need one: please don't judge me too harshly on it!
Small note: I am using CRUD Controllers made with the Entity First Framework in order to edit my database. As such, all creation, reading, updating, and deletion code has been provided for me. I have chosen not to add such basic, common code. If it is needed, I can add it. I will add what the Edit Action looks like:
public ActionResult Edit(string id)
{
Report report = db.Reports.Find(id);
return View(report);
}
It accepts a string as an id, ReportId is the id used and it IS a string. It is a randomly generated GUID string made with the GUID.NewGuid().ToString() function. I will also be doing the comparison of names with:
Model.UserName == User.Identity.Name.ToString()
Which was shown earlier. Sorry if this is too much text, I wanted to provide as much info as possible and not make anyone mad. If more info is needed, it can certainly be provided. So at the end of the post, the major question actually comes down to: which of the above two methods is best? And, if it's the first one, how do I implement something like that?
Thanks for your help!
Unless I'm completely misunderstanding you, you just want .Where()
Like this:
var reports = db.Reports.Where(r => r.genre == inputGenre);
This would get you an IEnumerable of Report, which you could then use however you wish.