Dynamic MVC Model Server side validation

Question

I have the following view:

@model dynamic


    @Html.AntiForgeryToken()


    
        

        
    

    
        
            
                @{
                    foreach (var obj in Model)
                    {
                        var kvpObj = (KeyValuePair)obj;
                        var entityProp = (EntityAttributeProperties)kvpObj.Value;
                        
                            @if (entityProp.IsHiddenField)
                            {
                                
                            }
                            else if (entityProp.IsFormField)
                            {
                                var isReadOnly = entityProp.IsReadonly ? "readonly" : "";
                                IHtmlString validationRules = Html.Raw(string.Empty);
                                if (entityProp.ValidationRules != null)
                                {
                                    validationRules = entityProp.ValidationRules;
                                }

                                @Html.Label(entityProp.Name, new { @class = labelClass })
                                
                                    @switch (@entityProp.Type)
                                    {
                                        //... many cases


                                        default:
                                            
                                            break;
                                    }
                                
                            }
                        
                    }
                }
            
        
    





@section Scripts {
    
}

And in the controller I get my values using FormCollection:

public ActionResult SaveItem(FormCollection form)
        {
         ...
         newValue = typeConverter.ConvertFromString(form[entityAttribute.Name]);
         ...                                                   
         }    
   }

My question is the following:

How can I establish Server-side validation on such dynamic model? Can I use FormCollection somehow? Possibly build dynamic view model somehow? If anyone has experience in this please consider giving a suggestion(answer).

Update: Making Detail page with ViewModel insted of dynamic model

So, After much refactoring I appear to be again stuck with server-side validation:

So now I have this ViewModel:

public class DynamicItemViewModel
{
    public Guid Id { get; set; }
    public List Properties { get; set; }
}

this detail page:

@model ExactDistillation.Models.DynamicItem.DynamicItemViewModel

    
        @using (Html.BeginForm("SaveItem", "DynamicItem", FormMethod.Post, new { @class = "form-horizontal", @id = "formDynamicItem" }))
        {
            @Html.AntiForgeryToken()

            @Html.HiddenFor(x => x.Id)
            
                

                
            

            
                
                    
                        Item
                    
                    
                        @{
                            for (int i = 0; i < Model.Properties.Count; i++)
                            {
                                @Html.EditorFor(m => Model.Properties[i], "EntityAttributeProperties", "Properties[" + i + "]")
                            }
                        }
                    
                
            
          }

And this is how I define EntityAttributeProperties page:

@model EntityAttributeProperties


    @if (Model.IsHiddenField)
    {
        @Html.HiddenFor(x => x.Value)
    }
    else if (Model.IsFormField)
    {
        @Html.Label(Model.Name, new { @class = "col-sm-5 col-md-4 col-lg-3" })

        
            @switch (Model.Type)
            {
                --- Many cases

                default:
                    @Html.DynamicTextBoxFor(m => m.Value, null, Model.IsReadonly, Model.ValidationRules)
                    break;

            }
        
    }

EntityAttributesProperties looks the following way:

public class EntityAttributeProperties
{
    public string Name { get; set; }
    public string DisplayName { get; set; }
    public object Value { get; set; }
    public EntityAttributeDataTypeEnum Type { get; set; }
    public short Order { get; set; }
    public bool IsFormField { get; set; }
    public bool IsReadonly { get; set; }
    public bool IsHiddenField { get; set; }
    public Dictionary ValidationRules { get; set; }
}

So, I am trying to make server-side validation for Model, but I am stuck, because I don't find any elegant solution to my problem, just solutions in which I have to do a lot of hardcoding (which I don't like).

Here is how I receive the form Submit:

 public ActionResult SaveItem(DynamicItemViewModel model)
        {
            List entityAttributes = GetItemEntityAttributes();
            DataObject dataObject = _dbContext.DataObjectCollection.FirstOrDefault(x => x.Id == model.Id);

            if (dataObject != null)
            {
                JObject json = JObject.Parse(dataObject.Value);
                dynamic dynJson = JsonConvert.DeserializeObject(dataObject.Value);

                // Possibly loop through all entity attributes and separately make a custom validation ?
                // Or somehow create custom Model State for validation ?

            }
            return View("Detail", model);


        }

I will appreciate any suggestion on how to approach the problem with server side validation.

Thanks.

thmshd · Accepted Answer

I'm adding another Answer because the Question changed heavily.

A good approach is to use the IValidatableObject Interface. So you add this Interface to your EntityAttributeProperties class and have to override the Method Validate. for simple validation like required fields, you use so called validation Attributes.

Your EntityAttributeProperties class would be decorated like this:

public class EntityAttributeProperties : IValidatableObject
{
    public string Name { get; set; }

    [Required]
    public object Value { get; set; }

    ...

    public IEnumerable Validate(ValidationContext validationContext)
    {
        var results = new List();
        if (... /* some condition, e.g. specific EntityAttributeDataTypeEnum */)
        {
            // Do some validation

            // some other random test
            if (.../* something not right... */)
            {
                results.Add(new ValidationResult("your input was not valid!"));
            }
        }

        return results;
    }
}

You might need to also make your DynamicItemViewModel and IValidatableObject and loop through the Items, but sometimes MVC is smart enough to validate sub-items automatically, so you might need this:

 public class DynamicItemViewModel : IValidatableObject
{
    ...

    public IEnumerable Validate(ValidationContext validationContext)
    {
        return Items.SelectMany(x => x.Validate(validationContext));
    }
}

OK now in your Controller, you basically need to check your ModelState. The automatically generated ModelState Property contains all errors.

Dynamic MVC Model Server side validation

Answers (2)

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