CRUD Operations with DetailsView and EntityDataSource in Custom Server Control - asp.net

I am not a big fan of ASPX pages, drag-and-drop and so on. I'm building a portal with a single Default.aspx and every other thing is custom web part controls or server controls that other developers can build in compiled dll and users can upload to the portal themselves to add features to the portal. I've been battling with DetailsView crud operations with entitydatasource. I did a test.aspx page with drag and drop and everything worked fine but with 100% code behind, nothing is. No error is displayed but data are not being persisted to database. I tried catching the onUpdating event of the detailsview and yes the event was fired and I could enumerate the data submitted but why is it not persisted to database? Hope someone can help with this.
Here's my code (trying to create everything from codebehind and add them to placeholders on the page just for testing purpose before I move everything to web part):
public partial class Test : System.Web.UI.Page
{
private EntityDataSource eds = new EntityDataSource();
public DetailsView dtlview = new DetailsView();
protected void Page_Load(object sender, EventArgs e)
{
//Initialize Datasource
eds.ConnectionString = "name=DBEntities";
eds.DefaultContainerName = "DBEntities";
eds.EnableDelete = true;
eds.EnableFlattening = false;
eds.EnableInsert = true;
eds.EnableUpdate = true;
eds.EntitySetName = "EmailAccounts";
Controls.Add(eds);//I don't know if this is necessary
//Create DetailsView and configure for inserting on default
dtlview.DataSource = eds;
dtlview.AutoGenerateInsertButton = true;
dtlview.AutoGenerateDeleteButton = true;
dtlview.AutoGenerateEditButton = true;
dtlview.AutoGenerateRows = false;
dtlview.DefaultMode = DetailsViewMode.Insert;
dtlview.AllowPaging = true;
dtlview.DataKeyNames = new string[] { "ID" };
dtlview.AllowPaging = true;
//Create fields since autogeneraterows is false
BoundField bfID = new BoundField();
bfID.DataField = "ID";
bfID.HeaderText = "ID:";
BoundField bfUserID = new BoundField();
bfUserID.DataField = "UserID";
bfUserID.HeaderText = "User ID:";
BoundField bfDisplayName = new BoundField();
bfDisplayName.DataField = "DisplayName";
bfDisplayName.HeaderText = "Display Name:";
BoundField bfEmailAddress = new BoundField();
bfEmailAddress.DataField = "EmailAddress";
bfEmailAddress.HeaderText = "Email:";
BoundField bfPassword = new BoundField();
bfPassword.DataField = "Password";
bfPassword.HeaderText = "Password:";
BoundField bfOutgoingServer = new BoundField();
bfOutgoingServer.DataField = "OutgoingServer";
bfOutgoingServer.HeaderText = "Outgoing server:";
BoundField bfIncomingServer = new BoundField();
bfIncomingServer.DataField = "IncomingServer";
bfIncomingServer.HeaderText = "Incoming Server:";
CheckBoxField chkfIsDefault = new CheckBoxField();
chkfIsDefault.DataField = "IsDefault";
chkfIsDefault.HeaderText = "Is Default?";
dtlview.Fields.Add(bfID);
dtlview.Fields.Add(bfUserID);
dtlview.Fields.Add(bfDisplayName);
dtlview.Fields.Add(bfEmailAddress);
dtlview.Fields.Add(bfPassword);
dtlview.Fields.Add(bfOutgoingServer);
dtlview.Fields.Add(bfIncomingServer);
dtlview.Fields.Add(chkfIsDefault);
dtlview.DataBind();
//Events handling for detailsview
dtlview.ItemInserting += dtlview_ItemInserting;
dtlview.ItemInserted += dtlview_ItemInserted;
dtlview.ModeChanging += dtlview_ModeChanging;
//Add controls to place holder
PlaceHolder2.Controls.Add(dtlview);
}
protected void dtlview_ItemInserting(object sender, DetailsViewInsertEventArgs e)
{
e.Values["UserID"] = GetCurrentUserID();
}
protected void dtlview_ItemInserted(object sender, DetailsViewInsertedEventArgs e)
{
}
protected void dtlview_ModeChanging(object sender, DetailsViewModeEventArgs e)
{
dtlview.ChangeMode(e.NewMode);
if (e.NewMode != DetailsViewMode.Insert)
{
dtlview.DataSource = eds;
dtlview.DataBind();
}
}
}

I think what you have to do is add :
OnContextCreating="XXXXDatasource_OnContextCreating"
OnContextDisposing="XXXXDatasource_OnContextDisposing"
To your EntityDataSource.
Then in you code :
protected void XXXXDatasource_OnContextCreating(object sender, EntityDataSourceContextCreatingEventArgs e)
{
e.Context = DBEntities.Entities;
}
protected void XXXXDatasource_OnContextDisposing(object sender, EntityDataSourceContextDisposingEventArgs e)
{
e.Cancel = true;
}
That way, your ObjectContext is correctly set to the EntityDataSource used by your DetailsView.
At least that's what I read as best practice (also look up one object context per page request)

Related

unable to persist data on postback in dotnetnuke7

I have my website running on dotnetnuke 7.4, i have a checklistbox which i bind on the page load, and after selecting items from it, user clicks on the submit button, the selected items should save in database, however when i click on the submit button, checklistbox gets blank, i tried to enable ViewState at :
Web.config level
Page Level
Control Level
But all in vain, it still unbinds checklistbox because of which everything disappears, i tried the same in plain .net and it works like a charm.
Is there any specific settings in dotnetnuke to support viewstate, or is there any other better option to achieve this.
Here's my code:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
Entities objEntities = new Entities();
List<Entities> obj = objEntities.GetList(2);
chkBox.DataSource = obj;
chkBox.DataTextField = "Name";
chkBox.DataValueField = "ID";
chkBox.DataBind();
}
}
protected void btnSubmit_Click(object sender, EventArgs e)
{
foreach (ListItem item in chkBox.Items)
Response.Write(item.Text + "<br />");
}
There's the issue. Remove that (!IsPostBack) check in your page_load event. Have your code to be like below. Else, only at first page load you are binding the datasource to control which gets lost in postback.
protected void Page_Load(object sender, EventArgs e)
{
Entities objEntities = new Entities();
List<Entities> obj = objEntities.GetList(2);
chkBox.DataSource = obj;
chkBox.DataTextField = "Name";
chkBox.DataValueField = "ID";
chkBox.DataBind();
}
OR, to be more efficient; refactor your code to a method like below and store the data object in Session variable like
private void GetDataSource()
{
List<Entities> obj = null;
if(Session["data"] != null)
{
obj = Session["data"] as List<Entities>;
}
else
{
Entities objEntities = new Entities();
obj = objEntities.GetList(2);
}
chkBox.DataSource = obj;
chkBox.DataTextField = "Name";
chkBox.DataValueField = "ID";
chkBox.DataBind();
Session["data"] = obj;
}
Call the method in your Page_Load event like
protected void Page_Load(object sender, EventArgs e)
{
GetDataSource();
}

Can't dynamically add controlvalidation to textbox

After several searches on the Internet finally decided to drop a question.
At runtime I want the following to happen.
If you push a button a textbox will be added to the controls and a custom validator must be attached to the textbox and fire.
It does not fire. Why?
Here is my code
Thank you for looking into this.
public partial class WebUserControl1 : System.Web.UI.UserControl
{
CustomValidator rv2 = new CustomValidator();
protected void Page_Init(object sender, EventArgs e)
{
if (!IsPostBack)
{
rv2.ID = "rev2";
rv2.ErrorMessage = "Not numeric input";
rv2.ClientValidationFunction = "";
rv2.ServerValidate += new ServerValidateEventHandler(GetalValidator);
Controls.Add(rv2);
}
}
protected void ButtonClick(object sender, EventArgs args)
{
TextBox tb1 = new TextBox();
tb1.ID = "tb2";
tb1.Visible = true;
tb1.Width = 30;
this.Controls.Add(tb1);`enter code here`
rv2.EnableClientScript = false;
rv2.ControlToValidate = "tb2";
}
private bool IsNumber(string someText)
{
int number;
bool result = Int32.TryParse(someText, out number);
return result;
}
protected void GetalValidator(object source, ServerValidateEventArgs args)
{
args.IsValid = IsNumber(args.Value);
}
}
here is part of code thorugh which you can add validation on your dynamically created control.
TextBox tb1 = new TextBox();
tb1.ID = "tb2";
tb1.Visible = true;
tb1.Width = 30;
RequiredFieldValidator regfv = new RequiredFieldValidator();
regfv.ID = "regfv";
regfv.ControlToValidate = tb1.ID;
regfv.ErrorMessage = "My Error";
this.Controls.Add(tb1);
this.Controls.Add(regfv);

gridview data is null in when passing gridview to another method

I bind the gridview in the following event:(subjectdropdown_SelectedIndexChanged)
I send the gridview in the following event as a parameter to another method:Button1_click event.
protected void subjectdropdown_SelectedIndexChanged(object sender, EventArgs e)
{
DataTable getmarkfdb = inter.getmarksfromdatabaseothers(comp);
if (getmarkfdb.Rows.Count > 0)
{
TemplateField lable1 = new TemplateField();
lable1.ShowHeader = true;
lable1.HeaderText = "AdmissionNumber";
lable1.ItemTemplate = new gridviewtemplate(DataControlRowType.DataRow, "AdmissionNumber", "AdmissionNumber", "Label");
studmarkgrid.Columns.Add(lable1);
TemplateField label2 = new TemplateField();
label2.ShowHeader = true;
label2.HeaderText = "RollNumber";
label2.ItemTemplate = new gridviewtemplate(DataControlRowType.DataRow, "RollNumber", "RollNumber", "Label");
studmarkgrid.Columns.Add(label2);
TemplateField label3 = new TemplateField();
label3.ShowHeader = true;
label3.HeaderText = "Name";
label3.ItemTemplate = new gridviewtemplate(DataControlRowType.DataRow, "Name", "Name", "Label");
studmarkgrid.Columns.Add(label3);
TemplateField extmep = new TemplateField();
extmep.ShowHeader = true;
extmep.HeaderText = "ExternalMark";
extmep.ItemTemplate = new gridviewtemplate(DataControlRowType.DataRow, "ExternalMark", "ExternalMark", "TextBox");
studmarkgrid.Columns.Add(extmep);
studmarkgrid.DataSource = getmarkfdb;
studmarkgrid.DataBind();
}
}
In the TextBoxTemplate column of the gridview I fill the Mark for student and in the following event i send the gridview to insertstumark method for read data from gridview and save into database. but in the insertstumark method gridview rows data are null.
protected void Button1_Click(object sender, EventArgs e)
{
comp.ACADAMICYEAR = acyeardropdown.SelectedItem.Text;
comp.MEDIUM = mediumdropdown.SelectedItem.Text;
string clas = classdropdown.SelectedItem.Text;
string[] cs = clas.Split('-');
comp.CLASSNAME = cs[0].ToString();
comp.SECTIONNAME =Convert.ToChar(cs[1].Trim().ToString());
comp.EXAMNAMES = examnamedropdown.SelectedItem.Text;
comp.SUBJECTID = subjectdropdown.SelectedValue.ToString();
// studmarkgrid.DataBind();
// System.Web.UI.WebControls.GridView grid = studmarkgrid;
// System.Web.UI.WebControls.GridView grid = ViewState["stdmarkgrid"] as System.Web.UI.WebControls.GridView;
DataTable studtable = null;
// System.Web.UI.WebControls.GridView grid = (System.Web.UI.WebControls.GridView)ViewState["stdmarkgrid"];
bool studm = inter.inserstumark(comp,stumarkgrid);
}
What is the problem. I tried to stored the gridview in viewstate. but in the following line it through the error. How to solve this problem?
System.Web.UI.WebControls.GridView grid = ViewState["stdmarkgrid"] as System.Web.UI.WebControls.GridView;
A lot of times, if the data is bound to the GridView too late in the Page Lifecycle, the GridView is rendered, and the data forgotten, so at the next PostBack, you won't have access to the GridView's underlying data source.
That looks like what's happening here. Just save the result of getmarksfromdatabaseothers to ViewState so you can access it again as necessary.

how to retain the value of global string variable even after page load in asp.net

I am having problems in retaining the string variable which I defined on the top of my scoop, everytime when page loads the string value becomes null. below is the snippet of the code:
public partial class Caravan_For_Sale : System.Web.UI.Page
{
string check;
PagedDataSource pds = new PagedDataSource(); //paging
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
BindGrid();
}
}
private void BindGrid()
{
DataTable dt = null;
switch (check)
{
case "0-1500":
break;
case "1500-2000":
dt = caravans.GetFilterbyPrice1();
break;
case "2000+":
break;
default:
dt = caravans.GetAllCaravans();
break;
}
// DataTable dt = caravans.GetAllCaravans();
pds.DataSource = dt.DefaultView;
pds.AllowPaging = true;
pds.PageSize = 3;//add the page index when item exceeds 12 //Convert.ToInt16(ddlPageSize.SelectedValue);
pds.CurrentPageIndex = CurrentPage;
DataList1.RepeatColumns = 3; // 4 items per line
DataList1.RepeatDirection = RepeatDirection.Horizontal;
DataList1.DataSource = pds;
DataList1.DataBind();
lnkbtnNext.Enabled = !pds.IsLastPage;
lnkbtnPrevious.Enabled = !pds.IsFirstPage;
doPaging();
}
protected void lnkPrice2_Click(object sender, EventArgs e)
{
LinkButton _sender = (LinkButton)sender;
check = _sender.CommandArgument;
// items["test"] = test;
DataTable dt = caravans.GetFilterbyPrice2();
if (dt.Rows.Count < 3)
{
lnkbtnNext.Enabled = false;
lnkbtnPrevious.Enabled = false;
}
CurrentPage = 0;
BindGrid();
}
protected void dlPaging_ItemCommand(object source, DataListCommandEventArgs e)
{
if (e.CommandName.Equals("lnkbtnPaging"))
{
CurrentPage = Convert.ToInt16(e.CommandArgument.ToString());
BindGrid();
}
}
The string check becomes null everytime when the dlPaging_ItemCommand becomes active(page loads). Any help or suggestions will be appreciated
As far as I know, you have two options:
1) Load it again.
Not sure if it's possible in your case. This is usually done when dealing with database queries.
2) Put it in the ViewState just like this:
ViewState["check"] = check;
And load it after with this:
string check = Convert.ToString(ViewState["check"]);
Your class is instantiated on every load so it will not have a global variable from page view to page view. You will need to store it somehow. Like in the querystring or a session. You can also use the viewstate.
For example
ViewState("Variable") = "Your string"
Viewstate is the way to go, as the other people have answered. Whatever you do, please don't stuff it in the session.

asp.net listbox vs winforms listbox

The following code is for winforms:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
listBox1.DataSource = Fruit.Get();
listBox1.DisplayMember = "Name";
listBox1.ValueMember = "ID";
}
private void listBox1_Click(object sender, EventArgs e)
{
object li = listBox1.SelectedItem;
Fruit fr = (Fruit) li;
label1.Text = fr.Name;
}
}
Is it possible to use the same technique in asp.net?
If no, then what is the alternative?
No, it's not possible in ASP.NET.
As an alternative, you can store your fruit items in Dictionary<string, Fruit> collection and you can get your selected Fruit like that :
// Assume that your datasource is Dictionary<string, Fruit> myFruits
Fruit fr = myFruits[listBox1.SelectedValue];
I don't think you can do it exactly like that, as I'm quite rusty in winforms, but here's how i'd try it in asp.net
1.) Bind your listbox in Page_PreRender()
listBox1.DataSource = Fruit.Get();
listBox1.DataTextField = "Name";
listBox1.DataValueField = "ID";
listBox1.DataBind();
2.) I'm not sure what the equivalent "OnClick" event would be, but you could hook into the SelectedIndexChanged event like so (triggered by another button):
var li = listBox1.SelectedItem;
label1.Text = li.Text;

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