Im trying to write a method which will allow me to search different DataTables, over different columns.
So far i have the following:
string selectedValue;
string searchColumn;
string targetColumn;
var results = (from a in dt.AsEnumerable()
where a.Field<string>(searchColumn) == selectedValue
select new
{
targetColumn = a.Field<string>(targetColumn)
}).Distinct();
Which kind of gets the job done, but I'm left with the column name as targetColumn rather than the actual column name I want.
Is there any way to resolve this?
Thanks in advance
CM
I make a LINQ to Datatables
public List<DataRow> Where(this DataTable dt, Func<DataRow, bool> pred)
{
List<DataRow> res = new List<DataRow>();
try {
if (dt != null && dt.Rows.Count > 0) {
for (i = 0; i <= dt.Rows.Count - 1; i++) {
if (pred(dt(i))) {
res.Add(dt(i));
}
}
}
} catch (Exception ex) {
PromptMsg(ex);
}
return res;
}
Usage :
var RowsList = dt.Where(f => f("SomeField").toString() == "SomeValue" ||
f("OtherField") > 5);
Related
I have a list view that list the activities. I have a way to get the selected values. What I don't know is how can I check if the user doesn't select any items from the list. How can I do this?
This is how I populate my list this will return at least 5-20 activities:
public void Get_Activities()
{
try
{
var db = DependencyService.Get<ISQLiteDB>();
var conn = db.GetConnection();
var getActivity = conn.QueryAsync<ActivityTable>("SELECT * FROM tblActivity WHERE Deleted != '1' ORDER BY ActivityDescription");
var resultCount = getActivity.Result.Count;
if (resultCount > 0)
{
var result = getActivity.Result;
lstActivity.ItemsSource = result;
lstActivity.IsVisible = true;
}
else
{
lstActivity.IsVisible = false;
}
}
catch (Exception ex)
{
//Crashes.TrackError(ex);
}
}
And this is how I get the values of the selected items on my list:
foreach(var x in result)
{
if (x.Selected)
{
// do something with the selected items
}
}
My question is like this
if(list.selecteditemcount == 0){
DisplayAlert("Error","Please select atleast 1 item","Ok");
}
In xamarin projects you can use Linq (using System.Linq). With Linq it's really easy to filter your list like that:
if(!list.Any(x => x.Selected == true))
{
// DisplayAlert...
}
This basically checks if any of your items has the value Selected='true'
Or without Linq you can do something like this:
if(list.FindAll(x => x.Selected).Count() == 0)
{
//DisplayAlert...
}
Use this
if (result.Any(x => x.Selected))
{
}
else
{
await DisplayAlert("Application Error", "Please choose at least one(1) activity", "Ok");
}
In my C# application i am using linq. I need a help what is the syntax for if-elseif- using linq in single line. Data, RangeDate are the inputs. Here is the code:
var Date1 = RangeData.ToList();
int record =0;
foreach (var tr in Date1)
{
int id =0;
if (tr.Item1 != null && tr.Item1.port != null)
{
id = tr.Item1.port.id;
}
else if (tr.Item2 != null && tr.Item2.port != null)
{
id = tr.Item2.port.id;
}
if (id >0)
{
if(Data.Trygetvalue(id, out cdat)
{
// Do some operation. (var cdata = SumData(id, tr.item2.port.Date)
record ++;
}
}
}
I think your code example is false, your record variable is initialized to 0 on each loop so increment it is useless .
I suppose that you want to count records in your list which have an id, you can achieve this with one single Count() :
var record = Date1.Count(o => (o.Item1?.port?.id ?? o.Item2?.port?.id) > 0);
You can use following code:
var count = RangeData.Select(x => new { Id = x.Item1?.port?.id ?? x.Item2?.port?.id ?? 0, Item = x })
.Count(x =>
{
int? cdate = null; // change int to your desired type over here
if (x.Id > 0 && Data.Trygetvalue(x.Id, out cdat))
{
// Do some operation. (var cdata = SumData(x.Id, x.Item.Item2.port.Date)
return true;
}
return false;
});
Edit:
#D Stanley is completely right, LINQ is wrong tool over here. You can refactor few bits of your code though:
var Date1 = RangeData.ToList();
int record =0;
foreach (var tr in Date1)
{
int? cdat = null; // change int to your desired type over here
int id = tr.Item1?.port?.id ?? tr.Item2?.port?.id ?? 0;
if (id >0 && Data.Trygetvalue(id, out cdat))
{
// Do some operation. (var cdata = SumData(id, tr.Item2.port.Date)
record ++;
}
}
Linq is not the right tool here. Linq is for converting or querying a collection. You are looping over a collection and "doing some operation". Depending on what that operation is, trying to shoehorn it into a Linq statement will be harder to understand to an outside reader, difficult to debug, and hard to maintain.
There is absolutely nothing wrong with the loop that you have. As you can tell from the other answers, it's difficult to wedge all of the information you have into a "single-line" statement just to use Linq.
I want to data in gridview for a particular mail_id. but wheneven i add this where condition its not showing anything. please help
if (!IsPostBack)
{
var mail = lblmail.Text;
var result = from test in je.jobposting orderby test.post_date where test.c_j_email==mail select test;
foreach (var items in result)
{
gvjob.DataSource = result;
gvjob.DataBind();
}
}
Is this better?
{
var mail = lblmail.Text;
// here, I assume jobposting is a DataTable
if (0 < je.jobposting.Rows.Count) {
var result = from test in je.jobposting orderby test.post_date where test.c_j_email==mail select test;
if (result.Any()) {
gvjob.DataSource = result;
gvjob.DataBind();
} else {
Response.WriteLine("No Match for c_j_email=" + mail + ".");
}
} else {
Response.WriteLine("<b>No Data in jobposting DataTable!</b>");
}
}
I'm a newbie in asp.net so I'm hoping you could give me some help on my dropdownlist bound to a table.
Here's the scenario:
I have a table Account with fields UserId, UserName and Type. The Type field contains 3 items: 'S', 'A', and 'U'. Each user has his own Type. I have a dropdownlist named 'ddlType' which is already
bound on the Account table. However, I want the options of the dropdownlist to be displayed as 'Stakeholder', 'Approver', and 'User' instead of displaying letters/initials only. Since I do not prefer making any changes in the database, how can I change those options through code behind?
Here's my code:
public void BindControls(int selectedUserId)
{
DataTable dtAccount = null;
try
{
dtAccount = LogBAL.GetAccountDetails(selectedUserId);
if (dtAccount.Rows.Count > 0)
{
lblUserId.Text = dtAccount.Rows[0]["UserId"].ToString();
txtUserName.Text = dtAccount.Rows[0]["UserName"].ToString();
ddlType.SelectedValue = dtAccount.Rows[0]["Type"].ToString();
}
}
catch (Exception ex)
{
throw ex;
}
finally
{
dtAccount.Dispose();
}
}
Any help from you guys will be appreciated. Thanks in advanced! :D
You can bind Dropdownlist in codebehind.
Get your data "Type" into array. Make array two dimentional and assign values to it.
After having data your array will looks like this,
string[,] Types = { { "Stakeholder", "S" }, { "Approver", "A" }, { "User", "U" } };
Now assign values to Dropdown,
int rows = Types.GetUpperBound(0);
int columns = Types.GetUpperBound(1);
ddlType.Items.Clear();
for (int currentRow = 0; currentRow <= rows; currentRow++)
{
ListItem li = new ListItem();
for (int currentColumn = 0; currentColumn <= columns; currentColumn++)
{
if (currentColumn == 0)
{
li.Text = Types[currentRow, currentColumn];
}
else
{
li.Value = Types[currentRow, currentColumn];
}
}
ddlType.Items.Add(li);
}
I haven't tested it but hopefully it will work.
I have a gridview in my user layer that uses a business layer method as its datasource, and I want the gridview to support paging and sorting. When I returned an Ienumerable from the method, it will bring back all of the data. If I use Take/Skip to bring back only a page's worth, the gridview doesn't realize that there are many pages of data.
When I change the Ienumerable to an IQueryable, the DataBind() fails because the data has already been disposed of. I think this problem has something to do with when the query actually executes and it may have to do with the filters I am applying to the query (see below).
User Layer Code:
grdSelectedQuestionaires.DataSource = assessment.FilteredAssessmentList(filter);
grdSelectedQuestionaires.DataBind(); <-- Fails - "Cannot access a disposed object"
Business Layer Code:
public IQueryable<Assessment> FilteredAssessmentList(AssessmentSearchFilter filter)
{
using (PAQcDataLayerDataContext dc = new PAQcDataLayerDataContext())
{
var rows = (
from a in dc.vPAQSummaries
select new Assessment()
{
PAQNumber = a.PAQNumber.Trim(),
CustomerID = (int)a.CustomerID,
Department = a.Department.Trim(),
CustomerName = a.CustomerName.Trim(),
DOTNumber = a.DOTNumber.Trim(),
OrgName = a.OrgName.Trim(),
DateEntered = a.DateEntered,
GroupNumber = a.GroupNumber.Trim(),
JobTitle = a.JobTitle.Trim(),
FileNames = a.FileNames.Trim(),
AnalystType = a.AnalystType.ToString(),
Incumbents = a.Incumbents,
});
// Filter by Customer ID
if (filter.CustomerID > 0)
{
rows = rows.Where(r => r.CustomerID == filter.CustomerID);
}
else
{
rows = rows.Where(r => r.CustomerID != null);
}
// Filter by DOT Number
if (!string.IsNullOrEmpty(filter.DOTNumberFrom))
{
if (string.IsNullOrEmpty(filter.DOTNumberTo))
{
rows = rows.Where(r => r.DOTNumber == filter.DOTNumberFrom);
}
else
{
rows = rows.Where(r => r.DOTNumber.CompareTo(filter.DOTNumberFrom) >= 0
&& r.DOTNumber.CompareTo(filter.DOTNumberTo) <= 0);
}
}
// Filter by OrgName
if (!string.IsNullOrEmpty(filter.OrgName))
{
rows = rows.Where(r => r.OrgName.StartsWith(filter.OrgName));
}
// Filter by Group
if (!string.IsNullOrEmpty(filter.GroupNumberFrom))
{
if (!string.IsNullOrEmpty(filter.GroupNumberTo))
{
rows = rows.Where(r => r.GroupNumber == filter.GroupNumberFrom);
}
else
{
rows = rows.Where(r => r.GroupNumber.CompareTo(filter.GroupNumberFrom) >= 0
&& r.GroupNumber.CompareTo(filter.GroupNumberTo) <= 0);
}
}
if (filter.Skip > 0)
{
rows = rows.Skip(filter.Skip);
}
if (filter.Take > 0)
{
rows = rows.Take(filter.Take);
}
else
{
rows = rows.Take(100);
}
return rows.Distinct();
}
}
}
The paging problem was caused by the Using statement. Changing this:
using (PAQcDataLayerDataContext dc = new PAQcDataLayerDataContext())
{
...
}
to this:
PAQcDataLayerDataContext dc = new PAQcDataLayerDataContext();
Made paging work. Now I have to figure out how sorting works.