Cannot implicitly convert type 'bool? ' To 'bool'. An explicit conversion exists (are you missing a cast? ) In MVC?

Question

1.00/5 (2 votes)

See more:

Hello,

cannot implicitly convert type 'bool?' to 'bool'. An explicit conversion exists (are you missing a cast?) in MVC.

I am trying checkbox in my mvc application but its getting error.

@Html.CheckBoxFor(x => x.IsSelected) error in "IsSelected".

Please help me.

Thanks in Advance.

Ankit Agarwal
Software Engineer

What I have tried:

C#

[HttpPost]
        public string Index(IEnumerable<City> cities)
        {
            if (cities.Count(x => x.IsSelected) == 0)
            {
                return "You didn't select any city";
            }
            else
            {
                StringBuilder sb = new StringBuilder();
                sb.Append("You selected -");
                foreach (City city in cities)
                {
                    if (city.IsSelected)
                    {
                        sb.Append(city.Name + ",");
                    }
                }
                sb.Remove(sb.ToString().LastIndexOf(","), 1);
                return sb.ToString();
            }
        }

@Html.CheckBoxFor(x => x.IsSelected)

Posted 14-Dec-16 20:20pm

Agarwal1984

Updated 15-Dec-16 17:02pm

Add a Solution

Comments

F-ES Sitecore 15-Dec-16 4:19am

If IsSelected is a model designed to be mapped to a checkbox then it should be defined as "bool" and not "bool?" as a checkbox only has two states, not three. If possible change the definition of IsSelected.

4 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

#realJSOP · Answer 1 · 2016-12-15T02:24:00

Solution 3

Do this:

C#

if (cities.Count(x => x.IsSelected == true) == 0)

Posted 15-Dec-16 2:24am

#realJSOP

Comments

Richard Deeming 15-Dec-16 12:43pm

You're getting too far ahead - you've answered his next question! :D

And the one after that will probably be about the if (city.IsSelected) line.

#realJSOP 15-Dec-16 13:01pm

I try to answer as many questions as possible with one answer.

Mohamed Rafiq K · Answer 2 · 2016-12-14T22:10:00

Solution 1

Try with this

C#

@Html.CheckBoxFor(x => x.IsSelected.GetValueOrDefault())

Posted 14-Dec-16 22:10pm

Mohamed Rafiq K

Updated 15-Dec-16 1:04am

v2

Comments

Richard Deeming 15-Dec-16 13:05pm

This will result in an InvalidOperationException with the message "Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions".

Richard Deeming · Answer 3 · 2016-12-15T07:13:00

If you can't change the model property from bool? to bool, then you're going to have to use the CheckBox and LabelFor methods, rather than the CheckBoxFor method:

@Html.CheckBox(nameof(Model.IsSelected), Model.IsSelected ?? false)
@Html.LabelFor(m => m.IsSelected)

Alternatively, you could use EditorFor with a custom editor, as described in this StackOverflow answer[^].

Or, you could add a non-nullable wrapper property to your viewmodel, and use that with the CheckBoxFor method:

C#

public bool IsSelectedNotNull
{
    get { return IsSelected ?? false; }
    set { IsSelected = value; }
}

@Html.CheckBoxFor(m => m.IsSelectedNotNull)

Philippe Mori · Answer 4 · 2016-12-15T17:02:00

Usually, I would modify the view model and if the view model only purpose is to be a model for that view, you can always modify it.

Alternatively, if I would have many cases where I prefer to have a bool ? for a property and still have a check box, I would probably write an extension method that would handle that case.

Doing that however require to have a good understanding of C# as expression trees are somewhat unusual...

Cannot implicitly convert type 'bool? ' To 'bool'. An explicit conversion exists (are you missing a cast? ) In MVC?

4 solutions

Solution 3

Solution 1

Solution 4

Solution 5

Add your solution here

Preview 0