I have a view where I need to detect if a property is decorated with hidden input.
My property is defined as:
[HiddenInput(DisplayValue = false)]
public string UserName{ get; set; }
My attempt so far has been:
var column.Member = "UserName";
if (ViewData.ModelMetadata.HideSurroundingHtml == true &&
ViewData.Values.Contains(column.Member))
{
column.Visible = false;
}
I have read that I might be able to use "HideSurroundingHtml" to determine if the property should not be displayed.
Any ideas how to detect this?
You can use reflection to see if a specific property has an attribute.
Look at this question.
In the various answers a user also posted a snippet to create an extension method to check if a property has a specific attribute or not. Hope it helps
My solution to this problem is as follows:
I have created html helper that gives me array of names with properties that has been decorated with the "HiddenInput" attribute.
public static string[] GetListOfHiddenPropertiesFor<T>(this HtmlHelper htmlHelper)
{
Type t = typeof(T);
var propertyInfos = t.GetProperties()
.Where(x => Attribute.IsDefined(x, typeof(HiddenInputAttribute)))
.Select(x => x.Name).ToArray();
return propertyInfos;
}
this is all i needed
Related
How do I create the proper Linq expression for the following property with navigation: m.Model.Property1?
I have a model like this:
public class ViewModel
{
public object Model { get; set; } //=Model is acutally the EntityModel
}
public class EntityModel
{
public string Property1
}
I have now something like this but can't find the Property1.
For the 2 last lines below I can't find a proper solution to get this, so I can send it to the HtmlHelper
var parameter = Expression.Parameter(typeof(ViewModel), "m"); //=ViewModel
var baseType = Html.ViewData.Model.GetType(); //=typeof(ViewModel)
var navExpr = Expression.Convert(Expression.Property(parameter, "Model"), typeof(EntityModel));
var exprProp = Expression.Property(navExpr , "Property1"); //This should create {m.Model.Property1}
var navExpr2 = Expression.Convert(exprProp, typeof(object));
return Expression.Lambda<Func<EditViewModel, object>>(navExpr2, parameter);
You need to convert object to EntityModel. This can be achieved with Expression.Convert. Try changing your navExpr to this:
var navExpr = Expression.Convert(Expression.Property(parameter, "Model"), typeof(EntityModel));
In your code sample in question Property1 is actually a field, not a property (you can use Expression.PropertyOrField or Expression.Field if it is so).
I'm using ASP.NET MVC3 with Razor.
I have a boolean value in my model which I would like to render as a check box in my view. However, I would like the check box to indicate the reverse of the boolean state. In other words, selecting the check box should set the bound model object to false, not true, when the form is submitted. And vice versa.
I can do this to set the value attribute on the rendered check box input element:
#Html.CheckBoxFor(model => model.MyBoolean, new { value = "false" })
But the hidden input element that is automatically created still has a value of false. Thus they both have a value of false, which means the bound model object is always set to false.
So how can I force the HTML helper to set the hidden element to true and the check box element to false?
I know that (a) I could alter the model and the database, (b) I could alter the values with javascript just prior to submission, and (c) I could swap whatever value is received in the controller after submission. I may do one of these, but I'm not asking for possible solutions; I'm asking whether it is possible to make the HTML helper do as I wish. I have searched extensively and haven't seen this addressed anywhere in official or unofficial sources. It seems like they should have a "swap" option or something.
class ViewModel {
public bool MyBoolean {get;set;}
public bool DisplayValue {
get {
return ! MyBoolean ;
}
set {
MyBoolean = !value;
}
}
}
And bind to the DisplayValue as it's setter updates you MyBoolean property anyway.
EDIT:
After reading your question again:.
You could use HtmlHelper to do that - but instead of using a CheckBox you could use a dropdown. The dropdown will define the "oppisite" values and text.
myModelInstance.PossibleValues = new[] { new SelectListItem { Value = "false", Text = "Not false" }, new SelectListItem { Value = "true", Text = "Not true" } };
Notice how the description is the opposite meaning of what you want the model to be. So for eg. for true you may have text as "Hidden" and false you may have the text as "Visible", true for "Disabled" and false for "Enabled" etc.
Then in your View:
#Html.DropDownList(Model.MyBoolean.ToString(), Model.PossibleValues)
The model will be updated with the correct value without have to do boolean toggles before viewing or updating.
For future readers, in my own opinion, HtmlHelpers are designed to render Html (as the name suggests). My preference for creating different way to render items is to create EditFor and DisplayFor templates. To make sure this is highly reusable, I also create model designed specifically for these templates. With your design, my models and templates might look like:
/Models/Controller/ControllerActionViewModel.cs
public class ControllerActionViewModel
{
public ControllerActionViewModel()
{
this.CheckboxBoolTemplate = new CheckboxBoolTemplate(false, true);
}
[Display(Name = "My Boolean")]
public SelectBoolTemplate MyBoolean { get; set; }
}
/TemplateModels/ControllerActionViewModel.cs
public sealed class SelectBoolTemplate
{
private bool _valuesSwapped = false;
private bool? _value;
private bool _defaultValue = false;
public SelectBoolTemplate()
{
}
public SelectBoolTemplate(bool valuesSwapped)
{
this._valuesSwapped = valuesSwapped)
}
public SelectBoolTemplate(bool defaultValue, bool valuesSwapped)
{
this._defaultValue = defaultValue;
this._valuesSwapped = valuesSwapped)
}
public bool Value
{
get
{
if (this._value.HasValue)
{
return this._value.Value
}
return this._defaultValue;
}
set
{
this._value = value;
}
}
}
/Views/Shared/EditorTemplates/SelectBoolTemplate.cshtml
#model SelectBoolTemplate
#{
string propertyName = ViewContext.ViewData.ModelMetadata.PropertyName;
string fullPropertyName = ViewContext.ViewData.TemplateInfo.HtmlFieldPrefix;
string labelText = ViewContext.ViewData.ModelMetadata.DisplayName
?? ViewContext.ViewData.ModelMetadata.PropertyName;
}
#Html.LabelForModel()
#Html.Checkbox(fullPropertyName, Model.Value)
I know this is too late for the original query but for anyone reading in future there's an alternative way to handle checkboxes with reversed false/true for checked/unchecked which requires no changes to the model - create a checkbox for false and a hidden field for true
<input id="#Html.IdFor(model => model.BoolProperty)" name="#Html.NameFor(model => model.BoolProperty)" type="checkbox" value="false" #(Model.BoolProperty? "" : "checked=\"checked\"" ) />
<input name="#Html.NameFor(model => model.BoolProperty)" type="hidden" value="true" />
I am using the example at The Complete Guide To Validation In ASP.NET MVC 3 to create a RequiredIf validation attribute (it's about 1/3 down the page under the heading of "A more complex custom validator"). It all works fine with the exception of one scenario, and that is if I have the need to validate against a complex type. For example, I have the following model:
public class MemberDetailModel
{
public int MemberId { get; set; }
// Other model properties here
public MemberAddressModel HomeAddress { get; set; }
public MemberAddressModel WorkAddress { get; set; }
}
public class MemberAddressModel
{
public bool DontUse { get; set; }
// Other model properties here
[RequiredIf("DontUse", Comparison.IsEqualTo, false)]
public string StreetAddress1 { get; set; }
}
The problem is that when the attribute validation for the StreetAddress property is rendered, it get's decorated with the attribute of data-val-requiredif-other="DontUse". Unfortunately, since the address is a sub-type of the main model, it needs to be decorated with a name of HomeAddress_DontUse and not just DontUse.
Strangely enough, the validation works fine for server-side validation, but client-side unobtrusive validation fails with an JS error because JS can't find the object with a name of just "DontUse".
Therefore, I need to find a way to change the ModelClientValidationRequiredIfRule method to know that the property it is validating is a sub-type of a parent type, and if so, prepend the ParentType_ to the "otherProperty" field (e.g. otherProperty becomes HomeAddress_DontUse.
I have tried passing in typeof(MemberAddressModel) as a parameter of the attribute, but even when debugging the attribute creation, I can't seem to find any reference to the parent type of HomeAddress or WorkAddress from that type.
Based on the suggestion from The Flower Guy, I was able to come up with the following which seems to work. I simply modified the following in the customValidation.js file:
jQuery.validator.addMethod("requiredif", function (value, element, params) {
if ($(element).val() != '') return true;
var prefix = getModelPrefix(element.name); // NEW LINE
var $other = $('#' + prefix + params.other); // MODIFIED LINE
var otherVal = ($other.attr('type').toUpperCase() == "CHECKBOX") ? ($other.attr("checked") ? "true" : "false") : $other.val();
return params.comp == 'isequalto' ? (otherVal != params.value) : (otherVal == params.value);
});
I also added the following method to that file (within the JQuery block so as to be only privately accessible):
function getModelPrefix(fieldName) {
return fieldName.substr(0, fieldName.lastIndexOf(".") + 1).replace(".","_");
}
Cannot do it exactly right now, but the problem is in the client javascript function:
jQuery.validator.addMethod("requiredif" ...
The js is not sophisticated enough to cope with complex view models where there may be a model prefix. If you take a look at Microsoft's jquery.validate.unobstrusive.js (in the Scripts folder over every MVC3 application), you will find some useful methods including getModelPrefix and appendModelPrefix. You can take a similar approach and change the requiredIf validation method - take a look at the equalto method in jquery.validate.unobstrusive.js for a helping hand.
I want mt view to have the check box checked by default,
I tried something like this.
#Html.CheckBoxFor(model=>model.GenericsOK, new { id = ViewBag.GenericsOK, #checked = true })
and also
#Html.CheckBoxFor(model=>model.GenericsOK, new { id = ViewBag.GenericsOK, #checked = "checked"})
in both cased it give the below error.
String was not recognized as a valid Boolean.
My property is defined as this.
private bool _deafaultchecked = true;
[Display(Name = "Generics Ok")]
public bool GenericsOK
{
get { return _deafaultchecked; }
set { _deafaultchecked = value; }
}
any suggestions please?
Since i could not find a solution or this.
i got this done like this.
#Html.CheckBox("GenericsOK", true, new {id=ViewBag.GenericsOK, name="GenericsOK" })
this works for my requirement.
thanks for all who helped me.
In your controller's Create method (I presume), have you tried this?
public ActionResult Create()
{
return View(new YourModelClass { GenericsOk = true });
}
In the controller action where you create the model just set that field value to true.
For example
return View(new DriverCsvModel{SendEmails = true});
You should be using the state of the model, rather than forcing the UI into a checked state.
You will want to remove the #checked="checked" portion of the HTML attributes. If the viewmodel property is a boolean then it is unnecessary when you use the CheckBoxFor
In the default constructor for your model class, you can set the "GenericsOK" property to "True"
Here's a scenario:
I have an autocomplete plugin (custom) that keeps a hidden field of JSON objects (using a specific struct).
I've created an Html helper that helps me easily bind to a specific custom model (basically, it has a JSON property that is for two-way binding and a property that lets me deserialize the JSON into the appropriate struct):
public class AutoCompleteModel {
public string JSON { get; set; }
public IEnumerable<Person> People {
get {
return new JavaScriptSerializer().Deserialize<Person>(this.JSON);
}
set {
this.JSON = new JavaScriptSerializer().Serialize(value);
}
}
}
This works great and I can model bind using the default binder #Html.Autocomplete(viewModel => viewModel.AutoCompleteModelTest). The HTML helper generates HTML like:
<input type="text" id="AutoCompleteModelTest_ac" name="AutoCompleteModelTest_ac" value="" />
<input type="hidden" id="AutoCompleteModelTest_JSON" name="AutoCompleteModelTest.JSON" value="{JSON}" />
The problem is this is not the best way for consumers. They have to manually set the People property to an array of Person structs. In my data layer, my domain objects probably will not be storing the full struct, only the person's ID (a corporate ID). The autocomplete will take care of looking up the person itself if only given an ID.
The best scenario will be to call it like this:
#Html.Autocomplete(domainObject => domainObject.PersonID) or
#Html.Autocomplete(domainObject => domainObject.ListOfPersonIDs
I would like it to work against the string property AND against the custom AutoCompleteModel. The autocompleter only updates a single hidden field, and that field name is passed back on postback (the value looks like: [{ "Id":"12345", "FullName":"A Name"},{ "Id":"12347", "FullName":"Another Name" }]).
The problem is, of course, that those domain object properties only have an ID or array of IDs, not a full Person struct (so cannot be directly serialized into JSON). In the HTML helper, I can transform those property values into a struct, but I don't know how to transform it back into a simple type on POST. The solution I need would transform an ID into a new Person struct on page load, serializing it into the hidden field. On POST, it would deserialize the generated JSON back into a simple array of IDs.
Is a custom model binder the solution I need? How can I tell it to work both with a custom model AND simple types (because I don't want it applied to EVERY string property, just need it to deal with the values given by the HTML helper).
I figured it out, it's possible!
To clarify, I needed to: transform a string or string array (of IDs) into a JSON structure for my hidden field value, then on post back, deserialize the JSON in the hidden field and transform the struct back into a simple string or string array (of IDs) for my domain object's property.
Step 1: Create a HTML helper
I had done this already, but only for accepting my custom AutoCompleteModel type. I needed one for a string and an Enumerable of string type.
All I did was generate my Person struct(s) from the value of the property and serialize them into JSON for the hidden field the Autocompleter uses (this is an example of the string helper, I also have a nearly identical one for IEnumerable<string>):
public static MvcHtmlString AutoComplete<TModel>(
this HtmlHelper<TModel> htmlHelper,
Expression<Func<TModel, string>> idProp)
where TModel : class
{
TModel model = htmlHelper.ViewData.Model;
string id = idProp.Compile().Invoke(model);
string propertyName = idProp.GetPropertyName();
Person[] people = new Person[] {
new Person() { ID = id }
};
// Don't name the textbox the same name as the property,
// otherwise the value will be whatever the textbox is,
// if you care.
MvcHtmlString textBox = htmlHelper.TextBox(propertyName + "_ac", string.Empty);
// For me, the JSON is the value I want to postback
MvcHtmlString hidden = htmlHelper.Hidden(propertyName, new JavaScriptSerializer().Serialize(people));
return MvcHtmlString.Create(
"<span class=\"AutoComplete\">" +
textBox.ToHtmlString() +
hidden.ToHtmlString() +
"</span>");
}
Usage: #Html.AutoComplete(model => model.ID)
Step 2: Create a custom model binder
The crux of my issue was that I needed this binder to only apply to certain properties, and they were strings or string arrays.
I was inspired by this article because it used Generics. I decided, hey, we can just ask people what property they want to apply the binder for.
public class AutoCompleteBinder<T> : DefaultModelBinder
where T : class
{
private IEnumerable<string> PropertyNames { get; set; }
public AutoCompleteBinder(params Expression<Func<T, object>>[] idProperties)
{
this.PropertyNames = idProperties.Select(x => x.GetPropertyName());
}
protected override object GetPropertyValue(
ControllerContext controllerContext,
ModelBindingContext bindingContext,
PropertyDescriptor propertyDescriptor,
IModelBinder propertyBinder)
{
var submittedValue = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
if (submittedValue != null && this.PropertyNames.Contains(propertyDescriptor.Name))
{
string json = submittedValue.AttemptedValue;
Person[] people = new JavaScriptSerializer().Deserialize<Person[]>(json);
if (people != null && people.Any())
{
string[] IDs = people.Where(x => !string.IsNullOrEmpty(x.ID)).Select(x => x.ID).ToArray();
bool isArray = bindingContext.ModelType != typeof(string) &&
(bindingContext.ModelType == typeof(string[]) ||
bindingContext.ModelType.HasInterface<IEnumerable>());
if (IDs.Count() == 1 && !isArray)
return IDs.First(); // return string
else if (IDs.Count() > 0 && isArray)
return IDs.ToArray(); // return string[]
else
return null;
}
else
{
return null;
}
}
return base.GetPropertyValue(controllerContext, bindingContext, propertyDescriptor, propertyBinder);
}
}
GetPropertyName() (translate LINQ expression into a string, i.e. m => m.ID = ID) and HasInterface() are just two utility methods I have.
Step 3: Register
Register the binder on your domain objects and their properties in Application_Start:
ModelBinders.Binders.Add(typeof(Employee), new AutoCompleteBinder<Employee>(e => e.ID, e => e.TeamIDs));
It's only a little bit annoying to have to register the binder for specific properties, but it's not the end of the world and provides a nice, smooth experience working with my autocompleter.
Any comments are welcome.