I m getting null in checking view state null condition but ViewState name is not null , I enabled ViewState property .This methods calling inside a for each loop .In some objects View state not null but majority getting null.I haven't set ViewState in any other places.
private void SetSelectedDates(string viewStateName, System.Web.UI.WebControls.Calendar calanderControl)
{
var variable = ViewState[viewStateName];
var dateTimeList = new List<DateTime>();
if (ViewState[viewStateName] != null)
{
dateTimeList = (List<DateTime>)ViewState[viewStateName];
}
else
{
}
}
Try this.Put double quotes in viewstatename
private void SetSelectedDates(string viewStateName, System.Web.UI.WebControls.Calendar calanderControl)
{
var variable = ViewState[viewStateName];
var dateTimeList = new List<DateTime>();
if (ViewState[viewStateName] != null)
{
dateTimeList = (List<DateTime>)ViewState["viewStateName"];
}
else
{
}
}
Use like this
ViewState["viewStateName"]
View state data is stored in one or more hidden fields as
base64-encoded strings. You can access view state information using
the page's ViewState property, which exposes a dictionary object.
Because the data in view state is stored as a string, only objects
that can be serialized can be stored.
Related
My stored procedure, instead of returning zero rows, returns one with most of the columns NULL. When my .Net code sees such data, I wish to force it to display the EmptyDataTemplate. How?
Thanks Win,
In the LinqDataSource Selecting event handler I check if the data source has a size of one and has a null value for one of the key fields and then I pass in this to the LinqDataSourceSelectEventArgs' Result:
using (var dataContext = new WebDataContext())
{
var report = from row in dataContext.GetReport()
select new Report()
{
AccountCode = row.AccountCode //,
//...
}
}
if (report.Count() == 1 && report.ToList()[0].AccountCode == null)
{
var emptyReport = report.ToList();
report.Clear();
e.Result = emptyReport;
}
else
{
//...
e.Result = matrixReport;
//...
}
Given is a Workflow Foundation 4 runtime that is working against a website ;)
We need to get the arguments of workflows to show the user an editor to enter the arguments. For that we need all arguments with names, types and - default values, as well as an indication whether an argument is required.
Workflows are stored as XAML files.
How to do that? The data seems to be in the Activity Metadata which seems to be not avaialble outside the Workflow. In addition, the Workflow Engine ModelService is for the Designer and has a lot of overhead.
Any easy way to retrieve this information?
I've already done something similar. Reflection might be your best (and only) option if you want a generic approach.
// Just an holder for InArgument informations
class InArgumentInfo
{
public string InArgumentName { get; set; }
public string InArgumentDescription { get; set; }
public bool InArgumentIsRequired { get; set; }
}
static ICollection<InArgumentInfo> GetInArgumentsInfos(Activity activity)
{
var properties = activity.GetType()
.GetProperties()
.Where(p => typeof(InArgument).IsAssignableFrom(p.PropertyType))
.ToList();
var argumentsCollection = new Collection<InArgumentInfo>();
foreach (var property in properties)
{
var descAttribute = property
.GetCustomAttributes(false)
.OfType<DescriptionAttribute>()
.FirstOrDefault();
string description = descAttribute != null && !string.IsNullOrEmpty(descAttribute.Description) ?
descAttribute.Description :
string.Empty;
bool isRequired = property
.GetCustomAttributes(false)
.OfType<RequiredArgumentAttribute>()
.Any();
argumentsCollection.Add(new InArgumentInfo
{
InArgumentName = property.Name,
InArgumentDescription = description,
InArgumentIsRequired = isRequired
});
}
return argumentsCollection;
}
This way you can not only retrieve the argument's name but also other information hold by the argument's attributes. For example I choose to give argument an user-friendly name through [Description] attribute (eg. instead of MyPropertyName user sees "My Property Name").
Note: if you can ensure that you activity is an ActivityBuilder or DynamicActivity they both have Properties property that you can use, but the principle is the same.
Load it as DynamicActivity and iterate over Properties property
var dynamicActivity = ActivityXamlServices.Load(foo) as DynamicActivity
foreach(DynamicActivityProperty prop in dynamicActivity.Properties)
{
// ...
}
UPDATE: Missed default value part
foreach (var prop in dynamicActivity .Properties)
{
object defaultValue;
if (prop.Value == null)
{
defaultValue = null;
}
else
{
Type genericTypeDefinition = prop.Type.GetGenericTypeDefinition();
if (genericTypeDefinition == typeof(InArgument<>) || genericTypeDefinition == typeof(InOutArgument<>))
{
var valueProp = prop.Value.GetType().GetProperty("Expression", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.DeclaredOnly);
var expression = valueProp.GetValue(prop.Value, null);
var expressionValueProp = expression.GetType().GetProperty("Value");
defaultValue = expressionValueProp.GetValue(expression, null);
}
}
}
Not totally guaranteed, there are some checks you have to do.
I've got data returned from my JavaScript client that just includes the data that has changed. That is, I may have an array with each row containing 10 columns of JSON downloaded, but on the Update, only the data that is returned to me is the data that got updated. On my update, I only want to update those columns that are changed (not all of them).
In other words, I have code like below but because I'm passing in an instance of the "President" class, I have no way of knowing what actually came in on the original JSON.
How can I just update what comes into my MVC3 update method and not all columns. That is, 8 of the columns may not come in and will be null in the "data" parameter passed in. I don't want to wipe out all my data because of that.
[HttpPost]
public JsonResult Update(President data)
{
bool success = false;
string message = "no record found";
if (data != null && data.Id > 0)
{
using (var db = new USPresidentsDb())
{
var rec = db.Presidents.FirstOrDefault(a => a.Id == data.Id);
rec.FirstName = data.FirstName;
db.SaveChanges();
success = true;
message = "Update method called successfully";
}
}
return Json(new
{
data,
success,
message
});
}
rec.FirstName = data.FirstName ?? rec.FirstName;
I would use reflection in this case because the code will be too messy like
if (data.FirstName != null)
rec.FirstName = data.FirstName
.
.
.
and so on for all the fields
Using reflection, it would be easier to do this. See this method
public static void CopyOnlyModifiedData<T>(T source, ref T destination)
{
foreach (var propertyInfo in source.GetType().GetProperties())
{
object value = propertyInfo.GetValue(source, null);
if (value!= null && !value.GetType().IsValueType)
{
destination.GetType().GetProperty(propertyInfo.Name, value.GetType()).SetValue(destination, value, null);
}
}
}
USAGE
CopyOnlyModifiedData<President>(data, ref rec);
Please mind that, this won't work for value type properties.
I am data binding to many FormView controls using EF entity instances, but I have to resort to this ridiculous kludge in order to achieve what I want without using EntityDataSource controls:
propertyHeaderSection.DataSource = new List<PropertyDetailsModel> { _propertyDetails };
I suspect I will have to derive my own control from FormView and enable it to accept an almost POCO as a data source. Where do I start?
This is my implementation, sort of the same idea as patmortech, but i also found out that the ValidateDataSource method on the BaseDataBoundControl is what throws the exception at run-time if your datasource isn't enumerable.
public class CustomFormView : System.Web.UI.WebControls.FormView
{
public override object DataSource
{
get
{
if (!(base.DataSource is IEnumerable))
return new[] {base.DataSource};
return base.DataSource;
}
set
{
base.DataSource = value;
}
}
// This method complains at run time, if the datasource is not
// IListSource, IDataSource or IEnumerbale
protected override void ValidateDataSource(object dataSource)
{
//base.ValidateDataSource(dataSource);
}
}
EDIT:
Considering the suggestion, i've made some changes to the way i check if the assigned DataSource is enumerable or not. I have also managed to create a sample app (VS 2010 Solution) to demo the changes. The app can be downloaded from http://raghurana.com/blog/wp-content/attachments/FormViewDataProblem.zip
In short this is what i am checking to ensure that the existing datasource can be enumerated already or not:
public static bool CanEnumerate( this object obj )
{
if (obj == null) return false;
Type t = obj.GetType();
return t.IsArray ||
t.Implements(typeof (IEnumerable).FullName) ||
t.Implements(typeof (IListSource).FullName) ||
t.Implements(typeof (IDataSource).FullName);
}
Please feel free to suggest more changes, if this isnt quite the desired functionality. Cheers.
Not sure it's the best idea in the world, but this is how you could derive from FormView to allow single object data source values. It basically does the same check that the ValidateDataSource does internally, and then creates a list wrapper for the item if it's not already a valid type.
public class SingleObjectFormView : System.Web.UI.WebControls.FormView
{
public override object DataSource
{
get
{
return base.DataSource;
}
set
{
//will check if it's an expected list type, and if not,
//will put it into a list
if (! (value == null || value is System.Collections.IEnumerable || value is System.ComponentModel.IListSource || value is System.Web.UI.IDataSource) )
{
value = new List<object> { value };
}
base.DataSource = value;
}
}
}
I am working on an ASP.Net MVC app and I want to show a confirmation page after the user edits some data. What I would like to show is a list of the pending changes that the user made to the model.
For example,
Are you sure you want to make the following changes:
FieldName:
Previous Value: XXX
New Value: YYY
I know I can read my stored value from the database and compare it with the POSTed object but I want this to work generally. What would be some good ways to approach this?
To clarify, I am looking for a general way to get a "diff" of the pending changes. I already know how to get the previous and pending changes. Kind of like how TryUpdateModel() can attempt to update any Model with posted values. I'd like a magical GetPendingModelChanges() method that can return a list of something like new PendingChange { Original = "XXX", NewValue = "YYY"} objects.
You might be doing this already but I wouldn't send my model to the view, create a viewmodel. In this case I would map the model data to the viewmodel twice, my viewmodel might contain OrderInput and OrderInputOrig. Then stick OrderInputOrig in hidden fields. On post back you can compare the values and then redirect, if something changed, to a display view with the original and the changes for confirmation.
Maybe something like this:
[HttpPost]
public ActionResult Edit(CustomerInput cutomerInput)
{
var changes = PublicInstancePropertiesEqual(cutomerInput.OriginalCustomer, cutomerInput.Customer);
if (changes != null)
{
cutomerInput.WhatChangeds = changes;
return View("ConfirmChanges", cutomerInput);
}
return View();
}
public ActionResult ConfirmChanges(CustomerInput customerInput)
{
return View(customerInput);
}
from: Comparing object properties in c#
public static Dictionary<string, WhatChanged> PublicInstancePropertiesEqual<T>(T self, T to, params string[] ignore) where T : class
{
Dictionary<string, WhatChanged> changes = null;
if (self != null && to != null)
{
var type = typeof(T);
var ignoreList = new List<string>(ignore);
foreach (System.Reflection.PropertyInfo pi in type.GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance))
{
if (!ignoreList.Contains(pi.Name))
{
var selfValue = type.GetProperty(pi.Name).GetValue(self, null);
var toValue = type.GetProperty(pi.Name).GetValue(to, null);
if (selfValue != toValue && (selfValue == null || !selfValue.Equals(toValue)))
{
if (changes == null)
changes = new Dictionary<string, WhatChanged>();
changes.Add(pi.Name, new WhatChanged
{
OldValue = selfValue,
NewValue=toValue
});
}
}
}
return changes;
}
return null;
}
Coming in very late here, but I created a library to do this on MVC models and providing "readable" diffs for humans using MVC ModelMetadata:
https://github.com/paultyng/ObjectDiff
It gives me output when I save a Model similar to:
Status: 'Live', was 'Inactive'
Phone: '123-456-7898', was '555-555-5555'
Etc.
use the TempData Dictionary.
TempData["previousValue"];
TempData["newValue"];