C# - How To Restrict A Data Annotation's Usage To A Particular Property's Data Type
Mar 31, 2011
I have a validation attribute that inherits from ValidationAttribute. However, the particular usage of this attribute applies to lists only (IEnumerable really). How can I specify the usage of this property to only be used with items that inherit from IEnumerabe?
Is there a way to enforce a class only to be used in ASP.NET ? So that it can't be referenced in a WinForm app or throw exception when instantiated. Is there some kind of .NET class attribute for this purpose?
I'm trying to understand when to use the type property and when to use the dbtype property. I looked online but couldn't find a good article that said when and why.
I've just installed MVC 3 and have the following problem. Even if I try to run the sample project, that is included in MVC 3 installation, when I go to the Register form, only the Required attribute causes validation. The Email Format attribute doesn't work,which means I can enter non-email string into the email field and it submits the form without any error messages.
i have a field username which i want to have as a label in the edit.aspx and as a typical textbox in create.aspx . i have applied datannotation class . how would i do that. in the edit mode it is always going model.isvalid ==false . so what i did had a textbox there with the label and hid it . it is working fine now . but is there any clean way this is done in dataannotation
Technically I have the Data Annoations working with Linq to SQL classes - the problem is when validation passes. When UpdateModel() tries to do its thing i can an error:The model of type 'MyProject.Models.Employee' could not be updated.What i did was i created a partial class for Employee (that is generated by linq to sql), then stuck a Meta Data class on top of it for the validation
Wanting to create custom data annotation validation. Are there any useful guides / samples on how to create them?
Firstly: StringLength with minimum and maximum length. I'm aware .NET 4 can do this, but want to do the same in .NET 3.5, if possible being able to define minimum length only (at least x chars), maximum length only (up to x chars), or both (between x and y chars).
Secondly: Validation using modulus arithmetic - if the number is a valid length, I wish to validate using the Modulus 11 algorithm (I have already implemented it in JavaScript, so I guess it would just be a simple porting?)
Update: Solved second problem, was just a case of copying over the JavaScript implementation and making a few tweaks, so don't need a solution for that.
I am using a model but as I want to have clean views I use the viewmodel approach which is like a downsized model which I map in my controller actions before sending to the view or getting it back in a HttpPost attributed action.
My question is: where to put the data annotation attributes. On the viewmodel classes or on the model? If I get it clearly the viewmodel annotations are used for the client side generation of validation right?
Do does that mean I have to put data annotations everywhere on both model and viewmodel?
I have custom class level validation attribute, inheriting from ValidationAttribute, on my model.
How come it doesn't register a key in the ModelState when its IsValid is false? I can see the the error message in the ModelState.Values collection, but the ModelState.Keys collection only shows an empty string "". Can I provide a key for it - presumably this is because its not assigned to a property?
I wanna be able to use ModelState.Remove in my controller to remove this error upon a certain condition, but I have no Key!
Something is wrong in ASP.NET MVC 2 on client side validation. If I have form for create records in database and all fields are required, validation is triggered only then when I write something in field and delete it. If I go to field, stay this field empty and press Tab key validation isn't triggered.
Here somebody else write about the same problem: [URL]
I have found hints that MVC 2 recognises the 'buddy class' type of property metadata, where data annotation attributes are applied to a 'buddy' metadata class, and the MetadataType on the actual entity class points to that buddy class, as below. However, as below, it seems the only attribute that makes any difference to the rendered UI is DisplayName. Why are the other attributes like DataType, Required, and ReadOnly not working? I.e. why can I enter text in a read only field? Why do I not get an error when a required field is empty? Why does the DataType attribute have no apparent effect? Why does EditorForModel not include validation messages?
[MetadataType(typeof(CustomerMetadata))] public partial class Customer { public class CustomerMetadata { [ScaffoldColumn(false)] public object CustomerId { get; set; } [DisplayName("CustomerNo.")] [ReadOnly(true)] [Required(AllowEmptyStrings = false, ErrorMessage = "Customer No. is required.")] public object CustomerNo { get; set; } } }
I find behaviour the same whether I use an explicit LabelFor and TextBoxFor for each model property, or a single EditorForModel for the whole model.
So I've eagerly added the System.ComponentModel.DataAnnotations namespace to my model.
I've added things such as:
[Required] [DisplayName("First Name")] public string first_name {get;set;}
I really like these attributes because they save me from having to write custom T4 and/or modify views heavily. This way, I can regenerate a view confident that it will add the display names I want, etc.
The problem comes in when I started building a DataGrid helper inspired by the one in ASP.NET MVC2 unleashed. In this helper, Stephen uses reflection to get at the column headings.
var value=typeOf(T).GetProperty(columnName).GetValue(item,null) ?? String.Empty;
Well, the trouble is I don't want to retrieve the property name. I want to retrieve the value for the DisplayName attribute.
My first attempt at this was to look inside the Attributes property of the PropertyInfo class. Unfortunately, none of the data annotations show up as an attribute.
Is there a way to retrieve the data annotations using reflection?
I am a MVC newbie & am lost in various ways validation can be implemented in my application.
I created a custom model-level data annotation validator attribute, but am unable to display its error message in the view. Basically, I have let's say 5 properties in the Entity class Job (model-level custom attribute called UniqueKeywords defined on it):
1) LoginID: value comes in the URL
2) Title: Required property level attribute defined on it
3) CatID1, CatID2, CatID3 - 3 categoryIDs - these are dropdowns in the view with same list of keywords in all 3.
I want to mandate that the values picked by the user in all 3 category dropdowns should be different.
With reference to the code pasted below, here is the explanation of what happens:
When I submit the form without specifying a title or picking anything from any of the 3 category dropdowns, the validation occurs for the property level Required attribute as well as model level uniquekeywords attribute, but the error is displayed only next to the required field "Title". I can confirm that the custom validation also works by filling in some text in the Title field & then re-posting the form...this re-displays the view, but the error message "Category cannot be duplicated" is not displayed.
I have generated entity framework designer classes . After Generating the designer what is the most nicest and cleanest way to apply data annotation to the properties there . I have 3 classes there
When I click submit, It does the validation on the server side, I kinda like it to validate on the Client instead of taking a trip to the server right away.
I'm trying to follow the demo from this link to add a jqGrid to an MVC app.
I have a table named Companies that I'm trying to display in a grid. A Company simply contains an ID and a Name.
I'm running into an error in my controller function:
public JsonResult DynamicGridData(string sortIndex, string sortOrder, int page, int rows) { int pageIndex = Convert.ToInt32(page) - 1; int pageSize = rows; var companies = companiesRepository.Companies.OrderBy(sortIndex + " " + sortOrder).Skip(pageIndex * pageSize).Take(pageSize); //Error here ... }
I'm getting an error on the line that is calling OrderBy():
The type arguments for method 'System.Linq.Enumerable.OrderBy(System.Collections.Generic.IEnumerable, System.Func)' cannot be inferred from the usage. Try specifying the type arguments explicitly.
I really have no idea what the error means, and I haven't been able to find an explanation. I'm not sure what is causing this error on a simple OrderBy function.
i am using file upload, i wanted to restrict the files showing in the dialog box to images only. That is 'Files of Type' in the dialog box should be .jpg,.jpeg,.gif,.bmp,.png
I am retrieving list of projects and project IDs using autocompleteextender. Is it possible to restrict the user to type further if the input doesn't retrieve any value from database. Though, I have found a solution by calling function through OnClientPopulated. But this function calls back the webservice "GetCompletionList" method. I don't want to recall one method two times. is there any other way?