I followed this post:DataTable using Server Side Processing.
Inside default.aspx, I am calling .ashx using:
<script type="text/javascript">
$(function () {
$('#example').dataTable({
'bProcessing': true,
'bServerSide': true,
'sAjaxSource': '/data.ashx'
});
});
On Page_Load event of defaut.aspx:
Employee emp=new Employee();
emp.name="abc";
emp.addr="pqr";
emp.phone="123";
Where Employee is the name of Class.
How can I pass the Employee Object to Data.ashx?
I tried using HttpContext.Current.Session but is shows Session object as null.
Please Help.
To Access the session Inside I used IRequiresSessionState interface as below:
public class Data : IHttpHandler, System.Web.SessionState.IRequiresSessionState
{
public void ProcessRequest(HttpContext context)
{
// get Employee object from session here
Employee emp =(Employee)HttpContext.Current.Session["employee"];
}
}
Ofcourse to set an Employee object in session, on Page_Load event of defaut.aspx:
Employee emp=new Employee();
emp.name="abc";
emp.addr="pqr";
emp.phone="123";
HttpContext.Current.Session["employee"]=emp;
NOTE:
There are two interfaces present to make access available to HttpSession in Generic Handler:
IRequiresSessionState
Using this interface we can read and write the session variables.
IReadOnlySessionState
Using this interface we can only read and cannot write or edit the session variables.
For more information check this link: IRequiresSessionState vs IReadOnlySessionState
Related
Situation
We have a controller where users can submit any number of E-Mail addresses to invite other (potential) members as friends. If an address is not found in the database, we send an E-Mail message to that user. Since the user does not has to wait for this process to complete in order to continue working this is done asynchronously.
Sending E-Mails can take a long time if servers respond slowly, are down or overloaded. The E-Mail sender should update the database according to the status received from the E-Mail server, so for example setting the friend request into "Error" state, when a permanent failure occurs, for example if the address does not exists. For this purpose, the E-Mail component implements the function SendImmediateAsync(From,To,Subject,Content,Callback,UserArg). After the message has been delivered (or it failed), the Callback is called with certain arguments about the Delivery state.
When it eventually calls the delegate, the DbContext object has already been disposed (since the controller has been too) and I cannot manually create a new one using new ApplicationDbContext() because there is no constructor that accepts a connection string.
Question
How can I write to the database long after the controller has been disposed? I have not yet figured out how to manually create a DbContext object for myself. An object of type ApplicationDbContext is passed to the constructor of the Controller and I hoped I could instantiate one for myself, but the Constructor has no arguments I can supply (for example connection string). I want to avoid to manually create an SQL Connection and assemble INSERT statements manually and would prefer to work with the entity model we have already set up.
Code
The code shows the affected segment only without any error checking for readability.
[Authorize]
public class MembersController : Controller
{
private ApplicationDbContext _context;
public MembersController(ApplicationDbContext context)
{
_context = context;
}
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult Friends()
{
MailHandler.SendImmediateAsync(FROM,TO,SUBJECT,CONTENT,
delegate (Guid G, object any)
{
//THIS IS NOT WORKING BECAUSE _context IS DISPOSED
var ctx = _context;
Guid Result = (Guid)any; //user supplied argument
if (G != Guid.Empty)
{
ctx.MailConfirmation.Add(new MailConfirmation()
{
EntryId = Result,
For = EntryFor.FriendRequest,
Id = G
});
if (G == MailHandler.ErrorGuid)
{
var frq = _context.FriendRequest.SingleOrDefault(m => m.Id == Result);
frq.Status = FriendStatus.Error;
ctx.Update(frq);
}
ctx.SaveChanges();
}
}, req.Id);
//rendering view
}
}
First of all, when you are using EF Core with ASP.NET Core's dependency injection, each DbContext instance is scoped per-request, unless you have specified otherwise in ".AddDbContext". This means you should not attempt to re-use an instance of DbContext after that HTTP request has completed. See https://docs.asp.net/en/latest/fundamentals/dependency-injection.html#service-lifetimes-and-registration-options
DbContextOptions, on the other hand, are singletons and can be re-used across requests.
If you need to close the HTTP request and perform an action afterwards, you'll need to create a new DbContext scope an manage it's lifetime.
Second of all, you can overload DbContext's base constructor and pass in DbContextOptions directly. See https://docs.efproject.net/en/latest/miscellaneous/configuring-dbcontext.html
Together, this is what a solution might look like.
public class MembersController : Controller
{
private DbContextOptions<ApplicationDbContext> _options;
public MembersController(DbContextOptions<ApplicationDbContext> options)
{
_options = options;
}
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult Friends()
{
MailHandler.SendImmediateAsync(FROM,TO,SUBJECT,CONTENT, CreateDelegate(_options) req.Id);
}
private static Action<Guid, object> CreateDelegate(DbContextOptions<ApplicationDbContext> options)
{
return (G, any) =>
{
using (var context = new ApplicationDbContext(options))
{
//do work
context.SaveChanges();
}
};
}
}
public class ApplicationDbContext : DbContext
{
public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base (options) { }
// the rest of your stuff
}
This assumes, of course, that your "MailHandler" class is properly using concurrency to run the delegate so it doesn't block the thread processing the HTTP request.
Why not just pass the dbContext as the userArgs to your SendImmediateAsync? Then the dbContext will not get disposed and can be passed back when you do the callback. I'm pretty sure that should work.
Scenario is when new users add or signup an object of that user must be created in 'userPrivileges' class with some default values,
I am using below code for that
Parse.Cloud.beforeSave(Parse.User, function(request, response)
{
if(request.object.isNew())
{
var userPrivilege = Parse.Object.extend("userPrivileges");
var userPriv = new userPrivilege();
userPriv.set("userType","Normal");
userPriv.set("userID",request.object.id);
userPriv.set("submitQus",true);
userPriv.save();
response.success();
}
else
{
response.success();
}
});
The issue is object added to userPrivileges but doest not get User's objectId which I am assigning to 'userPrivileges' userID.. where I am wrong?
It is not possible to get objectID in beforeSave hook if the object isNew() because the object is not in the database yet, ergo doesn't have an id. You should use afterSave hook and existed() instead.
I have a component for editing db entity. It has #CommitAfter on onSuccess(). When it is on the separate page it works fine. I click update button, it saves data and redirects to view page.
Now I want to reuse it on the list page. By clicking on item it should appear. After editing and clicking update button on the component it should save item to db and hide itself.
To achieve this I modified component so I can set zone id for its form. Put component inside zone on the list page, added links for each item with event onSelectItem, which sets zone id for component and returns body of the zone.
It did show component and I could edit fields and hit update button. It updated item but redirected whole page to view page. I tried to return null in onSuccess() – but in this case it didn’t save data to db and zone also wasn’t refreshed. I also tried call page class from a component by using #InjectPage and return page.zone.getBody() – this does reload zone but still doesn’t save data though all methods passed w/o exception. Also it too bad to call page specific code inside a component. My other custom ajax calls do save data to db in methods with #CommitAfter.
So my question what is the correct way of doing this in Tapestry?
ContactsList.tml
<html t:type="layout" xmlns:t="http://tapestry.apache.org/schema/tapestry_5_3.xsd" xmlns:p="tapestry:parameter">
<t:form>
... list of contacts linked to onSelectContact()
</t:form>
<t:zone id="editContact" t:id="editContactZone">
<t:if test="selectedContact">
<t:contactform t:id="contactForm" />
</t:if>
</t:zone>
</html>
ListPage.java
public class ContactsList{
#InjectComponent
private Zone editContactZone;
#InjectComponent("contactForm")
private ContactForm contactForm;
#Property
private Contact selectedContact;
public Object onSelectContact(#RequestParameter(value = "id", allowBlank = false) Integer id) {
selectedContact = getContactById(id);
if (selectedContact != null) {
contactForm.setContact(selectedContact);
contactForm.setFormZone(editContactZone.getClientId());
}
return editContactZone.getBody();
}
}
ContactForm.tml
<div xmlns:t="http://tapestry.apache.org/schema/tapestry_5_1_0.xsd" xmlns:p="tapestry:parameter">
<t:form t:id="editContactForm" zone="prop:zone">
.... contact fields
</t:form>
</div>
ContactForm.java
public class ContactForm{
#InjectComponent("editContactForm")
private Form editContactForm;
#Property
private String zone;
#InjectPage
private ContactList listPage;
#InjectPage
private ViewContact viewContact;
#Property
protected Contact contact;
public void setContact(Contact contact) {
this.contact = contact;
}
public void setFormZone(String zone){
this.zone = zone;
}
#CommitAfter
public Object onSuccess() {
parseContact();
storeContact(); // calls DAO.store(contact)
return zone == null ? viewContact : listPage.onSelectContact(0); //don't like this in component code but at least it returns zone's body
}
}
You could pass a Block component parameter to the ContactForm containing the markup to render after #OnSuccess.
Or perhaps a better separation of concerns is to fire an event in the ContactForm which bubbles up to the page? Eg:
ContactForm.java
#Inject ComponentResources resources;
#CommitAfter
public void onSuccess() {
storeContact();
resources.triggerEvent("contactSaved", new Object[] { contact }, null);
}
ContactsList.java
#Inject AjaxResponseRenderer ajaxRenderer;
#Inject Zone someZone;
#Property Contact contact;
public void onContactSaved(Contact contact) {
this.contact = contact;
ajaxRenderer.addRender(someZone);
}
Also, why are you using #RequestParameter? Why not use event context?
ContactsList.tml
<t:loop source="contacts" item="contact">
<t:eventlink event="selectContact" context="contact">Edit ${contact.name}</t:eventlink>
</t:loop>
ContactList.java
Block onSelectContact(Contact contact) {
// doStuff
}
I am using code first with an existing database, EF5, Web API and Breeze and I havent used any of these techs before. I am writing my own pocos.
I am trying to expose a read only property that requires several table joins to obtain the data. If we were using Web API only, we could just run some sql, populate the property and send some JSON back to the client.
Because we are using EF and breeze this obviously changes quite alot.
For example:
public class Employee
{
[Key]
public int EmployeeID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
[NotMapped]
public string FooBar
{
get { return getFooBar(); }
}
}
private string getFooBar()
{
// Do stuff here
}
This will send FooBar back to the client in the JSON result but because it is not mapped, and consequently not in the Metadata, I dont seem to be able to use it within Breeze.
I have read articles that say I can do this when using designer based methods (ie edit the edmx file) but how can it be done using code first?
I am aware that I can extend a Breeze entity on the client side but Im not really sure how I would get this value which hasnt been mapped, after Breeze has created all of the entities.
What I really want is to extend my code first entity. I also vaguely understand that this might not be in line with EF ideals but I also struggle with the idea that I dont have the freedom to define what is and what isnt a property of my employee.
I dont need to track changes. I dont need to save. I dont seem to be able the use the EF context provider to join the (many) tables and get the data because the entities for each table dont share a primary key and dont inherit from the same class.
I think this SO post here suggests something similar but once again its for generated classes. Is there a way to do this? Thanks.
Edit
In reply to Wards suggestion I tried a few tests.
My client side constructor:
function Employee() {
this.DisplayName = ""; // unmapped property
};
My Controller:
function TestController($scope, $routeParams) {
var manager = new breeze.EntityManager('breeze/employees');
var metadataStore = manager.metadataStore;
metadataStore.registerEntityTypeCtor("Employee", Employee);
var query = new breeze.EntityQuery()
.from("Employees")
.orderBy("FirstName");
manager.executeQuery(query).then(function (data) {
// Check unmapped property name
var employeeType = metadataStore.getEntityType("Employee");
var unmapped = employeeType.unmappedProperties;
alert(unmapped[0].name) // Returns 'DisplayName'
alert(employeeType.dataProperties[3].name) // Returns 'DisplayName'
var prop = manager.metadataStore.getEntityType('Employee').getProperty('DisplayName');
alert(prop.name) // Returns 'DisplayName'
var first = data.results[0]
var fullName = first.DisplayName
alert(fullName) // Returns empty string
$scope.employees = data.results;
$scope.$apply();
}).fail(function (e) {
alert(e);
});
};
My Angular:
<div>
<ul>
<li data-ng-repeat="employee in employees">
{{employee.DisplayName}}
</li>
</ul>
</div>
So the property seems to be setup correctly as an unmapped property, but it only returns the empty string. If I change
this.DisplayName = ""; // unmapped property
to
this.DisplayName = "Foo"; // unmapped property
then DisplayName always contains "Foo". The values from the payload are not being applied to DisplayName.
Am I missing something?
It's pretty easy on the Breeze client as explained in the Extending Entities documentation topic: you define an unmapped property in a custom constructor and register that constructor.
var metadataStore = myEntityManager.metadataStore;
metadataStore .registerEntityTypeCtor("Employee", Employee);
function Employee ()
this.FooBar = ""; // unmapped property
};
Now the Breeze metadata includes a definition of the FooBar unmapped property. The server will send a value for FooBar to the client and Breeze will populate that client Employee entity (unmapped) property when it materializes Employee entities from a query.
How you obtain that FooBar property value on the server is up to you. I don't know enough about your app. What you've shown us is a perfectly valid Code First entity definition.
Maybe you're asking an Entity Framework question rather than a Breeze question.
One way to get this working has been discussed in this SO answer from CassidyK. Here is the code snippet.
proto.initializeFrom = function (rawEntity) {
// HACK:
// copy unmapped properties from newly created client entity to the rawEntity.
// This is so that we don't lose them when we update from the rawEntity to the target.
// Something that will occur immediately after this method completes.
var that = this;
this.entityType.unmappedProperties.forEach(function(prop) {
var propName = prop.name;
that[propName] = rawEntity[propName]; // CassidyK
//rawEntity[propName] = that[propName]; // Breeze
});
if (!this._backingStore) {
this._backingStore = { };
}
};
I dont know what the side effects of this are. Perhaps one of the Breeze devs can better explain.
It seems this is only a problem when Breeze is configured for Angular.
IE
breeze.config.initializeAdapterInstance("modelLibrary", "backingStore", true);
I am newbie to MVC and Play framework (Java). Instead of using Groovy for dynamic HTML, I made our own page with static HTML, I mean we haven't any Groovy expressions. Here, I have a controller "Customer", generates JSON object which has to be sent to an ajax call in view. I tried with render() method, seems I haven't used correctly. can you give me some idea to forward from here. thanks.
public static void customer(){
WordAPI objWordAPI=new WordAPI();
List<WordInfo> listObjWord= objWordAPI.MakeAPIObject(nSurveyId);
JSONSerializer modelSerializer=new JSONSerializer().exclude("NSpontanity","NWordRepresentativity","NWordValue","NWordFrequency","class").rootName("Words");
render("Application/wordcloud.html",modelSerializer.serialize(listObjWord));
}
and ajax call in view "wordcloud.html"
$.ajax({
url: "/customer",
dataType : 'json',
success: function (data) {
alert(data);
}
})
I believe this should work:
public static void customer(){
WordAPI objWordAPI=new WordAPI();
List<WordInfo> listObjWord= objWordAPI.MakeAPIObject(nSurveyId);
JSONSerializer modelSerializer=new JSONSerializer().exclude("NSpontanity","NWordRepresentativity","NWordValue","NWordFrequency","class").rootName("Words");
renderJSON(modelSerializer.serialize(listObjWord));
}
I've never used rootName before, I usually just do something more like this:
public static void refreshNotifications()
{
JSONSerializer notifySerializer = new JSONSerializer().include("message","notifyId","class").exclude("*");
List<Notification> notificationList = user.getNotifications();
renderJSON(notifySerializer.serialize(notificationList));
}
Side Note: With refreshNotifications I have a Security method I run before which verifies and populates the user object.