Quite simply How can I pass from Partial to page on construction:
_SiteLayout.cshtml
#{PageData["phoneNumber"]="072342342343";}
Page.cshtml
please call us on #PageData["phoneNumber"]
Ive tried things like this. What obvious step am I missing?
Its bring up blanks.
try use Session for this:
Session["phoneNumber"]="072342342343"
#Session["phoneNumber"]
You can also use the HttpContext.Items collection. It works about the same as the Session, but the collection is only kept alive for the duration of the request. I'm not sure how to most easily access it using Razor though. Read more about HttpContext.Items here.
Related
I need to get some Json to the client side from the server and it's somewhat troublesome as almost all tutorials assume an Ajax call to a separate action to get the Json.
This led me to think that there must be some reason why it is done this way. In Asp.Net MVC we can pass a Model along with the view to get the information but we can't seem to easily pass a Json object. Instead you are supposed to make a separate call to get this information.
What if the Json info is known when the page is generated, why not generate it at the same time?
I'm sorry if I wasn't clear enough. While it's nice to hear of ways to get Json to the client, the question is actually whether there is a specific reason the Ajax call method is much more popular, like security or anything like that.
Can you put something like this into your view? (rough pseudo code, assuming using a Razor view)
< script >
var myJSON = { Field: #model.Field, Field2: #model.Field2 };
< /script >
Because you do not need both at the same time... on the first call will be to get html (the view of the data - represented by a view model), and any ajax calls will be to get the possibly updated data (json serialized view model).
No reason why you can't. You could use the javacript serializer to create a JSON string that drop on the page. You could also create an action that return the json string that you called from a script tag.
What you want if you're using KnockOut, would be the Mapping plugin that turns an ordinary JS object, like that generated above, into an observable ready for KnockOut to use. See here from info. http://knockoutjs.com/documentation/plugins-mapping.html
You can use content-negotiation by setting accept header. This is considered a best practice (and according to some RESTful).
This needs to be supported and implemented at server as well. ASP NET MVC does not make it easy to support content-negotiation and you have to implement it yourself by if-else or using ActionFilter and implementing action selector.
Is
System.Web.HttpContext.Current.Session
the same as
System.Web.UI.Page.Session
?
They do indeed refer to the same instance, but if you look at the methods in Reflector, you can see that they behave a bit differently (in ways that are not likely to matter in most applications):
The call to Page.Session uses a
cached HttpSessionState reference.
The Page method will throw if
session state is not enabled, while
HttpSessionState.Session just
returns whatever is in the
"AspSession" bucket of its Items
collection.
Yup; they refer to the same instance.
There is no difference between the two.
I have built my first MVC solution and used the repository pattern for retrieving/inserting/updating my database.
I am now in the process of refactoring and I've noticed that a lot of (in fact all) the methods within my repository are hitting the database everytime. This seems overkill and what I'd ideally like is to do is 'cache' the main data object e.g. 'GetAllAdverts' from the database and to then query against this cached object for things like 'FindAdvert(id), AddAdvert(), DeleteAdvert() etc..'
I'd also need to consider updating/deleting/adding records to this cache object and the database.
What is the best apporoach for something like this?
My knowledge of this type of things is minimal and really looking for advice/guidance/tutorial to point me in the right direction.
Thanks in advance.
This just hit my radar, and I assume you have already solved the issue by now. But if not, I would look into Pre-Compiled LINQ Queries. Something like this:
private static Func<SomeDataContext, int, PersonDto> _getPersonByIdQuery =
CompiledQuery.Compile<SomeDataContext, int, PersonDto>(
(dataContext, personId) =>
dataContext.PersonDtos.where(c => c.PersonId == personId).FirstOrDefault()
);
Put something like that inside of your datacontext, then add an internal method in there to call it call it. Your retriever/saver will then call the internal method. Does that make sense? I can post more code if necessary..
Best of luck,
Justin
We heard a lot about the vulnerabilities of using QueryStrings and the possible attacks.
Aside from that, yesterday, an error irritated me so much that i just decide to stop using QueryStrings, i was passing something like:
Dim url As String = "pageName.aspx?type=3&st=34&am=87&m=9"
I tried to
Response.Write(url)
in the redirecting page, it printed the "type" as 3, then i tried it in the target page, it printed 3,0....i know this can be easily dealt with, but why? i mean why should i pass 3 and have to check for 3.0 in the next page's load to take my action accordingly???
So what should we use? what is the safest way to pass variables, parameters...etc to the next page?
You could use Cross-Page Postbacks.
Check also this article:
How to: Pass Values Between ASP.NET Web Pages
There are many options you can use, most of them requires you to build a strategy to pass variables between pages.
In most projects I use this strategy, I create a formVariables class to hold currently active items. it has properties which you will need to pass by querystring. and I store this class at session. and in my base page I read it from session. so in every page I get values over this object. the only negative thing about this method is to clean up items when you finished your work on it..
hope this helps.
I would sugest you avoid using Session to pass variables between pages as this breaks the stateless model of the web.
if you have just stored some values in session that relate to a certain page then the user uses their browsers back button to go back to the same page whcih should have a different state then you are not going to know about it.
It leads to the possibility of reading session values that are not relevant to the page the user is currently viewing - Which is potentially very confusing for the end user.
You will also run into issues with session expiration if you rely on it too much.
I personally try to avoid using session where possible in preference of hidden form values + query strings that can be read on postback + navigation.
The best / most secure way to pass info between pages is to use the session.
// On page 1:
this.Session["type"] = 3;
// On Page 2:
int type = (int)this.Session["type"];
You can store any kind of object in the session and it is stored on the server side, so the user can't manipulate it like a query string, viewstate, or hidden field
You said:
it printed 3,0....i know this can be easily dealt with, but why? i mean why should i pass 3 and have to check for 3.0
There's a difference between "3,0" (three comma oh) and "3.0" (three point oh). You also said that you were "passing something like".
In a query string, if you pass multiple values in the same key, they will be seperated with commas.
As all values are passed as strings there's no way that an int "3" is going to magically become decimal "3.0" unless you parse it as such when you request it.
I'd go back and double check what you are passing into your URL, if it ends up as something like:
pageName.aspx?type=3&st=34&am=87&m=9&type=0
Then when you read back
Request.QueryString["type"]
You'll get "3,0" back as the comma seperated list of values in that key.
First, in asp .net you can use several strategys to pass values between pages. You have viewstate too, however the viewstate store the value and the use is in different scenarios , you can use it too. Sessions instead, and of course by post in a form.
If your problem is the security, I recommended you to create 2 users for accesing the data. One user with read only access, this for accessing the pages ( Sql Inyection prevent ) and validate the data throw the querystring. And One with write access for your private zone.
Sorry, for my unreadeable English.
I like to use query string as I like users to be able to bookmark things like common searches and the like. E.g. if a page can work stand-alone then I like to it to be able to work stand-alone.
Using session/cross-page postbacks is cool if you needed to come from another page for the page you're on to make sense, but otherwise I generally find querystrings to be the better solution.
Just remember that query strings are unvalidated input and treat them with the caution you would treat any unvalidated input.
If you do proper security checks on each page load then the querystring is fine and most flexible IMHO.
They provide the most flexibility as the entry poitn to a page is not dependant on the sender as in some other options. You can call a page from any point within your own app or externally if needed via querystrings. They can also be bookmarked and manually modified for testing or direct manipulation.
Again the key is adding proper security and validation to the querystring, and not processing it blindly. Keep in mind that the seucirty goes beyond having edit or read access, depending on the data and user, they may not have access to the data with thos paranters at all, in cases where data is owned and private to specific users.
We have tried various methods, in an attempt to hide the querystring but in the end have gone back to it, as it is easier to do, debug, and manage.
Here's a wierd one. I'm reusing a code base that unfortunately must not be updated. This code makes a call to HttpContext.Current.Request.QueryString. Ideally, I need to push a value into this collection with every request that is made. Is this possible - perhaps in an HTTP Module?
Without using reflection, the simplest way to do it would be to use the RewritePath function on the current HttpContext object in order to modify the querystring.
Using an IHttpModule, it might look something like:
context.RewritePath(context.Request.Path, context.Request.PathInfo, newQueryStringHere!);
Hope this helps!
Ditto Espo's answer and I would like to add that usually in medium trust (specific to many shared hostings) you will not have access to reflection so ... RewritePath will remain your probably only choice.