IsReadOnly for a field is throwing exception

Question

Hello, I have a table where a few fields by certain users cannot be added during the create screen.  The first one I tried is a column called Status that has a choice list.  I set a default value in article_created() method.  As you can see in my last few lines of my code.  I used the status_isReadOnly if the user has the CanEditAllPermissions.  Yet when I go to my create screen, it throws an exception saying I cannot set value.  I have other fields which i need to do the same with, I am not sure why the code below is not working.  Would it be better to do a isvisible instead of isreadonly?  What would be the best way to not let certain users not able to add data to certain fields in the create screen.  Thanks

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.LightSwitch;
namespace LightSwitchApplication
{
    public partial class Article
    {
        partial void Article_Created()
        {
            //On Create screen when Open, show todays date in Entry Date field and Status = New
            this.EntryDate = System.DateTime.Today;
            this.Status = "New";
     
        }

        partial void Status_Changed()
        {
            //When Published Status is selected, the date published is set to Today
            if (this.Status.Equals("Published"))
            {
                this.DataPublished = System.DateTime.Today;
            }
        }

        partial void LinkAgents_Changed()
        {
            if (this.LinkAgents != null && this.Status == "New")
            {
                this.Status = "Assigned";
            }
        }

        partial void Status_IsReadOnly(ref bool result)
        {
            result = this.Application.User.HasPermission(Permissions.CanEditAll);
        }
   
        
    }
}

Answer 1

Hi Please try this

result = !this.Application.User.HasPermission(Permissions.CanEditAll);

Slight change of your code.

May this help you...

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Rashmi Ranjan Panigrahi

Answer 2

Rashmi, ok i did not get the exception if my user has the permission above.  However, the user that does not have the above permission, is when it throws the error of not being able to set the value, which is "new" based on my code above.  How can I fix it, since Status field has a default value in code.  Thanks for the help.

Answer 3

Change the Status_IsReadOnly method to return false in the case where a value has not been set yet. This way, the Article_Created method can set the value of Status and it will become immediately read-only afterwards:

partial void Status_IsReadOnly(ref bool result)
{
    // The property is read-only when the property has been set and the user does not have the edit permission
    result = !String.IsNullOrEmpty(this.Status) && !this.Application.User.HasPermission(Permissions.CanEditAll);
}

---

Justin Anderson, LightSwitch Development Team

Answer 4

Hi

As far i understand to your question, if you want to set dafault value in Status property when the property is read-only try the below code in your Article_Inserted method

partial void Article_Inserted(Article entity)
        {
            using (this.Application.User.AddPermissions(Permissions.CanEditAll)
            {
                entity.Status = "New";
            }
        }

May this will help you...

---

Rashmi Ranjan Panigrahi

Answer 5

The problem is client-side. In the scenario that the user does not have the permission, the this.Status = "New" line in the Article_Created method will throw an exception because the property is read-only (due to the user not having permission to change it). At this point in the scenario, server-side code (e.g. Article_Inserted) will not help.

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Justin Anderson, LightSwitch Development Team

Answer 6

Hi Justin

Thanks for your suggestion.

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Rashmi Ranjan Panigrahi

Answer 7

Justin, thanks for your help, as well as Rashmi.  I do have a question, what does the "!" in front of the query do, just make it True?

Thanks

Answer 8

The ! is the Boolean NOT operator; it turns true to false and false to true.

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Justin Anderson, LightSwitch Development Team