How Can I valid parent from child and child from parent?

Hello, First of all sorry for my poor english.

I want when RequiredDependentChild is different from null the RequiredDependentParent is required and when RequiredDependentParent is different from null the RequiredDependentChild is required.

This work with RequiredDependentParent different from null, so my RequiredDependentChild is required , thats ok

But I do not know how to do the inverse way.

I don’t want to put the RequiredDependentParent in ClassParent because in the real case there are many Properties.

How I can do that, would you help me please?

Thanks, this plugins is so good

My Models:

public class ClassParent
{       
    [Key]
    public int Id { get; set; }

    [Required]
    public string AlwaysRequired { get; set; }

    [RequiredIf("Child.RequiredDependentParent != null", ErrorMessage = "I am parent, You need fill me")]    
    public string RequiredDependentChild { get; set; }
          
    public ClassChild Child { get; set; }
}

public class ClassChild
{     
    [Key]
    public int Id { get; set; }
       
    [RequiredIf("")] //I don't know what to do here...
    public string RequiredDependentParent { get; set; }     
}

My fields

<div class="form-group">
            @Html.LabelFor(model => model.AlwaysRequired, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.AlwaysRequired, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.AlwaysRequired, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.RequiredDependentChild, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.RequiredDependentChild, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.RequiredDependentChild, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Child.RequiredDependentParent, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Child.RequiredDependentParent, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Child.RequiredDependentParent, "", new { @class = "text-danger" })
            </div>
        </div>

[jwaliszko]

Thank you for the sample.

Unfortunately out-of-the-box client-side support of back-references to the container (parent model) is not implemented. EA at client-side is pretty straightforward and designed to handle nested properties when explicitly provided to the view, without abilities to infer the context.

It’s a tricky stuff to achieve what you want. When using HTML helpers at the client-side, the more nested property, the more prefixed name. When reference to container is used in expression, what client-side script actually does, is looking for such a property within current context. It has no idea that it is a reference to a container.

In your case, the RequiredDependentChild property in the expression "Parent.RequiredDependentChild != null" makes client-side EA to be looking for the analogic input field within current model scope, i.e. Child.Parent.RequiredDependentChild. Child prefix corresponds with what HTML helper renders for nested property of your Child object.

The thing you could, do is providing the field EA is expecting to find, i.e.:

@Html.HiddenFor(m => m.Child.Parent.RequiredDependentChild) // hidden mock

Next, make the mocked field clone the behavior of the original (parent) one:

<script type="text/javascript">

    function Mimic(src, dest) {
        $(src).on(ea.settings.dependencyTriggers,
            function(e) {
                $(dest).val($(this).val());
                $(dest).trigger(e.type); // trigger the change for dependency validation
            });
    }

    $(document).ready(function () {
        Mimic('input[name="@Html.NameFor(m => m.RequiredDependentChild)"]',
              'input[name="@Html.NameFor(m => m.Child.Parent.RequiredDependentChild)"]');
    });

</script>

Please be aware that this a workaround for such specific cases like yours, when back-reference needs to be understood and properly handled by client-side EA logic.

[mauricioferrazs]

I did not understand 100% of its explanation because my English rsrs, but the code about Mimic I understood and worked perfectly, tomorrow I will test in my real scenario and after that I give you a feed back.

Is it possible in the future to make this change to a new release without the need for this javascript code?

Thank you very much for your effort in helping me, I appreciated it. : D