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Member Expression cannot convert an object with a null decimal number

I am working on an MVC project and would like to pass the property name to the Html.TextboxFor method. This is my view model.

public class RuleViewModel<T> where T : class, IValidatableObject
{
    private T _rule;
    public T RuleModel
    {
        get
        {
            return _rule
                ?? (_rule = Activator.CreateInstance<T>());
        }
    }

    public RuleMetadata Metadata { get; set; }

    public Expression<Func<RuleViewModel<T>, Object>> GetParameterByName(PropertyInfo pi)
    {
        var fieldName = Expression.Parameter(typeof(RuleViewModel<T>), "x");
        var fieldExpression = Expression.PropertyOrField(Expression.Property(fieldName, "RuleModel"), pi.Name);
        var exp = Expression.Lambda<Func<RuleViewModel<T>, Object>>(fieldExpression, fieldName);
        return exp;
    }

}

Then in the view I do it

  @foreach (var prop in Model.RuleModel.GetType().GetProperties())
    {
        var result = Model.Metadata.Columns.SingleOrDefault(m => m.ColumnName == prop.Name);
        if (result != null)
        {
            <td>
                @Html.TextBoxFor(Model.GetParameterByName(prop))
            </td>
        }
    }

The problem is that when the property is of type decimal ?, I get a, cannot convert the value with a zero number to an object error. I looked around and found that you can use Expression.Convert to fix this, but when I do this, I get an error in the view

Templates can only be used with access to a field, access to resources, an index of a one-dimensional array, or one-parameter expressions of a custom indexer.

. , , .

+3
1

, object TProperty TextBoxFor<TModel, TProperty>(). - Func<TModel, TProperty>, # , Func<TModel, decimal?> , Func<TModel, object>. Convert(), MVC , Convert.

, TextBoxFor<TModel, TProperty>() :

public Expression GetParameterByName(PropertyInfo pi)
{
    var fieldName = Expression.Parameter(typeof(RuleViewModel<T>), "x");
    var fieldExpression = Expression.PropertyOrField(
        Expression.Property(fieldName, "RuleModel"),
        pi.Name);
    var exp = Expression.Lambda(
        typeof(Func<,>).MakeGenericType(typeof(RuleViewModel<T>), fieldExpression.Type),
        fieldExpression,
        fieldName);
    return exp;
}

// ...

@InputExtensions.TextBoxFor(Html, (dynamic)Model.GetParameterByName(prop))
+2

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