My requirement is to create a custom data annotation attribute for my project. The requirement is to validate the min/ max length of a specific product from the database, which will be retrieved from the database using the ProductID. I have a dynamic page for each product where there are two fields called max length & min length. User inputs the values in these two fields which needs to be validated from the database. Product table contains all the products & one will be selected by passing a productId.
Please suggest some pointers to implement the above.
Thanks in advance.
This validation you can do only in the server side and not in client, so I see two options.
Remote Validation - You can use remote validation when you want to perform the validation and show the error message through ajax.
IValidatableObject - By implementing this interface in the class you can do both the validations at the same time and return all the validation error messages as a collection. By this way the validation will happen after the form is normally submitted.
Related
I am creating a new Joomla Component. I am able to create custom fields for the component backend forms - but I am not able to create Dynamic Custom Fields.
What I would like to do is have a field that is dynamical populated based on the value of a previous field. The easiest way to explain this is the simple country,state,city breakdown.
Field 1 = Country
Field 2 = State (Based on what the user selected as as Country in Field 1)
Field 3 = City (Based on what the user selected as State in Field 2)
The fields would of course need to be refreshed, reset as the user picks a different country etc.
The data to populate the fields would also all need to come from a database based on the previous fields value.
I am guessing this needs to be done via ajax or javascript or something? But wondering if there is an official way? Especially since there are database calls involved.
Please let me know if there is anything I can explain better..
David
I ended up just creating text fields but then validating the input to make sure the values added are correct.
My validation requirements for a the fields in a form are contained in an external table so that they can be updated without altering and rebuilding the code.
I have approximatley 100 fields with a mixture of validation requirements - range, required, regular expression and dependency on other fields. One example is date range validation. A date of birth field requires a date range which is between -10 years and -50 years of the current date.
I have read around the subject but have not identified a pattern for the complete solution.
I am using Visual Studio 2010 with MVC 3 and Entity Framework.
Any help with this would be gratefully received. Thanks in advance.
In a simple level I think you can still use the built-in Data-Annotations validation attributes to does the validation and for that you should map the validation rules stored in the table to the attributes.
I think all you have to do is create a custom model validation provider by inheriting the class ModelValidatorProvider. This class contains a single method called GetValidators that returns the collection validators for that model.
You have to implement the GetValidators method and in there you have to make a database call to get the validation rules for the model from the database (or from cache?) and convert them into ModelValidators. You could still use the built-in DataAnnotationsModelValidator to do the validations.
I would suggest you to look into the source code of DataAnnotationsModelValidatorProvider that will give you all the information. In that class what they are doing is basically iterating all the validation attributes applied to the model properties and converting them into ModelValidators through adapters and factories. In your case instead of attributes they are stored as records in tables and I don't think much work will be there.
I have page with spring form fields.
They're bind using command.
Couple of fields in form need to be update based on calculation from other fields.
Those fields can be modified by user.
How can I do that?
I think about trigger java calculation in model using onchanged in web page. But I don't know how access methods from model and how read fields from page.
I notice, that field are update by setter when page is submit. This is too late if I want calculate 'live' when depending fields are changing.
If you need these calculations to be done on server (java model)... I suggest to use input's onChange event as you said, send values with AJAX to server and calculate there, returning the result to client again for update UI in real-time.
With this approach, you will get the 'live thing' you are wondering for.
In Magento i've got a tab with a form in the Backend System > Configuration section with 2 input fields.
I'd like to manipulate the data from those two fields before their saved. Is that possible?
And if so, whats the cleanest way to do that.
Many thanks
These types of jobs are the purpose of "backend models". If a field has a backend_model configured, that backend model's _beforeSave() method will be invoked prior to the value being entered into the database.
See Mage/Paygate/etc/system.xml & search for <backend_model>
See Mage_Adminhtml_Model_System_Config_Backend_Encrypted::_beforeSave()
Suppose i have a 'View' for filling up form for renting a DVD , as per MVC architecture , either of 'Controller' or 'Model', who is supposed to validate the form data?
Thanks
You validation should be in Model section of MVC.
As models have various fields, only models can know what combination of inputs make that model valid. It's not just about whether a field is blank, or the input of that field matches some pattern, but sometimes this is a combination of field inputs, or the model's relationship to other models that determine the valid state.
All 3 are usually involved in the validation process if you follow the typical flow.
The model defines validation attributes such as the required or stringlength attributes. The controller checks the validation state of the model via ModelState.IsValid and makes decisions accordingly. The view may additional provide client-side validation for those same attributes. Don't rely solely on js to validate the form.
My suggestion would be to validate in the view with some form of validation binding, and then again in the model before persisting to any data store.