In web.config, why can't we have duplicate connection strings and handlers but on the other hand, we can have duplicates <appSettings> child elements with the same key name at the same level or down the inheritance hierarchy?
I don't this will complete answer to your question or not but I have some information that I would like to share.
If you look
ConfigurationManager.AppSettings
then it is NameValueCollection and If you give two key with same name default implementation will return latest value ( Last value in order for that key) but if you want to support multiple key support and you want it return all value for that key than you can replace appSettings default behavior with custom implementation.
http://www.codeproject.com/Articles/4302/How-to-make-AppSettings-work-with-multiple-values
But In case of connection string it is sealed class ConnectionStringSettingsCollection.
It is implement to support only one key with same name present and at web.config level it allow duplicate value for name but when you try to access it will throw error. It make sense in connection string case as well otherwise it get confused which to choose.
As per my point it is just implementing different way to support and reduce confusion.
Related
I am new to using hash table, and I want to know how to change the value of a specific existing key in a hash table. I tried to search but all that came up involved hash map, which I am not familiar with, and which I am not planning to use.
I am not sure whether hash tables only enables inserting and removing values, or whether it enables making a change to an existing key.
Also, please explain to me how to do so. (i.e. .put() means insert. what do I do to change?)
thanks.
Edited because, on reflection, the wording of the question seemed ambiguous, and might have assumed the wrong meaning initially.
You can't change the key, if that's what you meant. The key determines the position of an entry in the hash map/table (by definition), so if you change the key without changing the position, the map/table is now corrupt.
To change the key and change its position is simple: remove the entry under the old key, and add the same entry under the new key.
You can change the value associated with the key. There are several possible approaches. One is to just use put() with the same key to update the value; see the documentation for this. Another is to use entrySet() to get the set of key,value mappings, find the entry for your key, and use setValue() on that entry.
Of course, remove and re-add will also allow you to change the value.
I'm looking for a fast & elegant way of converting my object IDs with descriptive names, so that my autogenerated routes look like:
/products/oak-table-25x25-3-1
instead of
/products/5bd8c59c-fc37-40c3-bf79-dd30e79b55a5
In this sample:
uid = "5bd8c59c-fc37-40c3-bf79-dd30e79b55a5"
name = "Oak table (25x25) 3/1"
I don't even know how that feature could be named, so that I might google for it.
The problem that I see so far is the uniqueness of that "url-object-name", for example if I have two oak tables 25x35 in the db, and their names differ too little to be uniquely url-named but enough to fool the unique constraint in the db.
I'm thinking of writing that function for name-transform in SQL as an UDF, then adding a calculated field that returns it, then unique-constraining that field.
Is there some more mainstream way of achieving that?
One method is that employed by stackoverflow.com which in your case would be:
/products/5bd8c59c-fc37-40c3-bf79-dd30e79b55a5/oak-table-25x25-3-1
This ensures uniqueness, however the length of the UUID may be a deterrent. You may consider adding a sequential int or bigint identity value to the products table in addition to the uniqueidentifier field. This however would require an additional index on that column for lookup, though a similar index would be required for a Url having only a descritive string. Yet another method would be to use a hash value, seeded by date for instance, which you can compose with the descriptive name. It is simpler to rely on a sequential ID value generated by a database, but if you envision use NoSQL storage mechanisms in the future you may consider using an externally generated hash value to append.
Identity should have 2 properties: it should be unique and unchangable. If you can guarantee, that /products/oak-table-25x25-3-1 will never change to /products/oak-table-25x25-3-1-1 (remember, user can have bookmarks, that shouldn't return 404 statuscode)- you can use name as url parameter and get record by this parameter.
If you can't guarantee uniqueness or want to select record more faster - use next:
/products/123/oak-table-25x25-3-1 - get record by id (123)
/products/123/blablabla - should redirect to first, because blabla no exists or have anoher id
/products/123 - should redirect to first
And try to use more short identities - remember, that at web 2.0 url is a part of UI, and UI should be friendly.
MVC routing (actions) will handle spaces and slashes in a name. It will encode them as %20, and then decode them correctly.
Thus your URL would be /products/oak%20table%2025x25-3%2F1
I have done something very similar in an eCommerce platform I am working on.
The idea is that the URL without the unique ID is better for SEO but we didn't want the unique ID to be the product name that can change often.
The solution was to implement .NET MVC "URL slug only" functionality. The product manager creates "slugs" for every product that are unique and are assigned to products. These link to the product but the product ID and name can be changed whenever.
This allows:
domain.com/oak-table-25x25-3-1
to point to:
/products/5bd8c59c-fc37-40c3-bf79-dd30e79b55a5
(The same functionality can be used on categories too so domain.com/tables can point to domain.com/category/5b38c79c-f837-42c3-bh79-dd405479b15b5)
I have documented how I did this at:
http://makit.net/post/3380143142/dotnet-slug-only-urls
The MSDN documentation isn't precise on this point.
It says in one place: "Gets a collection of membership users where the user name contains the specified user name to match."
Later it says, "FindUsersByName returns a list of membership users where the user name matches the supplied usernameToMatch for the configured applicationName."
The SQLMembershipProvider supports wildcards, but the documentation doesn't say whether I must also do so with my custom membership provider.
Edit: I'm really asking more about the intent of the Membership Provider rather than what I should do in my specific situation.
The FindUsersByName function will do a match on the string you pass in.
If you want it to do a partial match then you need to add '%' on the end of the string you're searching for.
This sentence in the documentation explains it:
The SqlMembershipProvider performs its search using a LIKE clause against the usernameToMatch parameter. Any wildcards that are supported by SQL Server in LIKE clauses can be used in the usernameToMatch parameter value.
SO
"Gets a collection of membership users where the user name contains the specified user name to match."
is the accurate sentence if you do a search for "DAV*" you should get "Dave", "David, "Davis", etc.
Let's make it more restrictive (find exact match) to be sure that user 'joe' has no access to data of the user 'joel' :)
Anyway, do you really need to find a user given only part of it's name?
EDIT:
Now checked again the MSDN method you linked to, and it's name is FindUsersByName (users, not user) so the method is able to return more than one user. It this case I assume you should implement the code to return all matches.
If the method would be FindUserByName, then it is the opposite answer (you have the method GetUser for this)
I have an .aspx form with 20 fields that must be disable based on a users role and a status of a order record. Currently the application has 5 roles and 3 status, so I have 300 different possible conditions that I have to account for.
My first thought is to store each permutation in a table, then set the fields when the page loads by looping through the fields. Is there a better way? Please note, I am using .Net 2.0 and NOT MVC.
I'd probably store the details of each field, and then the roles and status that can edit them, and do it that way.
What are the rules for the system? Basically, are there really 300 possible conditions? Or is that really certain fields are only editable for certain status, and then only certain roles can edit those fields? Or is it that certain fields are available for certain roles as well?
If it's more of the former I'd probably have something like this:
Three primary tables (makes it easy to extend if you add a field, role or status):
Fields
Roles
Status
Then two link tables:
Field.Id and Role.Id
Field.Id and Status.Id
Then for any given order and user you can then find which Fields are editable for the order's current status, and the users role, and as you work through the fields set the access rights appropriately - however you set the controls - either dynamically generating them based on the collection you get back, or statically on the page.
If you have an issue where the Role can override the Status, you could also store a boolean in the Field/Role table, indicating whether the Field should be avaiable regardless of status.
Like another responder, we also use a Business Object framework called CSLA. CSLA implements field-level security checks by requiring class developers to do security checks in the property get/set calls. A typical property implementation looks like this:
Private mFirstName As String = ""
Public Property FirstName() As String
<System.Runtime.CompilerServices.MethodImpl(Runtime.CompilerServices.MethodImplOptions.NoInlining)> _
Get
CanReadProperty("FirstName", True)
Return mFirstName
End Get
<System.Runtime.CompilerServices.MethodImpl(Runtime.CompilerServices.MethodImplOptions.NoInlining)> _
Set(ByVal value As String)
CanWriteProperty("FirstName", True)
If value Is Nothing Then value = ""
If Not mFirstName.Equals(value) Then
mFirstName = value
PropertyHasChanged("FirstName")
End If
End Set
End Property
Notice the calls to CanReadProperty and CanWriteProperty. The second parameter specifies that the method should throw an exception if the user is not authorized to perform the specific read/write operation.
The implementation of the CanReadProperty and CanWriteProperty are provided by the framework's base class but should be reproducible without adopting the entire CSLA framework. The implementations check an AuthorizationRules data structure which defines who is allowed/denied Read/Write access based on roles. Often, the AuthorizationRules structure is populated during object creation.
Exposing the same CanReadProperty and CanWriteProperty methods to your presentation-tier allows you to enable/disable UI elements based on the current user's access rights. For example:
FirstNameTextBox.ReadOnly = Not CanWriteProperty("FirstName", false)
Hopefully this information will provide you with a good starting point for developing your own implementation. If you're interested in learning more about CSLA then check out Expert C# 2008 Business Objects.
I suggest to use third party framework to achieve this. We use CSLA framework in our projects. It allow us to set authorization at field level.
Using the Dynamics CRM I'm trying to create an instance of an entity. I would like to manually set the GUID, but if I had the attribute that is the primary key to the DynamicEntity, I get following error.
Service could not process request
I am building a DynamicEntity, and setting the [entityname]id attribute causes the request to fail. It's moving data between two CRM instances, so if anyone knows of a better way to copy records between CRMs, that'd work too. Otherwise, I'd like the GUID to match across instances... as that's the point of a GUID.
Happily, it IS possible to do this across two CRM instances! A co-worker knew the solution, so credit really belongs to him.
My mistake was creating a Property with type UniqueIdentifierProperty. The primary key attribute on an entity needs to be filled in with a KeyProperty. These two properties are nearly identical -- the Property types are, except that one holds a Key, the other a UniqueIdentifier. The Key/UniqueIdentifier both hold GUIDs. (Another day in the mind of Microsoft!)
Precisely, what I'm doing is creating a DynamicEntity, filling in the entity name, and filling in the majority of the attributes. The PK attribute (which you can determine from the metadata) can be filled in with a KeyProperty. I was filling it in with a UniqueIdentifierProperty, which CRM rejects and responds with a nondescript and unhelpful error message.
I apologize if I am over-simplifying the solution, but why not add a custom field in both instances that would be a mirror of the other instances guid?