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How to add a hyperlink in Excel DNA with SetValue?

One of +60 columns I pass to Excel is a hyperlink
private object GetApplicationUrl(int id)
{
var environmentUri = _configurationManager.Default.AppSettings["EnvironmentUri"];
return $"=HYPERLINK(\"{environmentUri}://TradingObject={id}/\", \"{id}\");";
}
this resolves external protocol and opens particular deal in another application. This works, but initially, the hyperlink formula is unevaluated, forcing the users to evaluate it first. I use object array:
protected void SetRange(object[,] range, int rows, int columns, ExcelCell start = null)
{
start = start ?? GetCurrentCell();
ExcelAsyncUtil.QueueAsMacro(
() =>
{
var data = new ExcelReference(start.Row, start.Row + (rows - 1), start.Column, start.Column + (columns - 1));
data.SetValue(range);
});
}
How can I force the excel to evaluate it?
I tried several things, but they did not work. For example:
return XlCall.Excel(
XlCall.xlcCalculateNow,
$"HYPERLINK(\"{environmentUri}://TradingObject={id}/\", \"{id}\")");
maybe I am using an incorrect flag or missing something.

I found out several ways to fix it, but not all of them worked as I expected. In short, I came up with calling the cell formula value instead.
private void SetFormulaColumn(List<int> ids, ExcelCell cell)
{
var wSheet = ((Application)ExcelDnaUtil.Application).ActiveWorkbook.ActiveSheet;
for (var i = 0; i < ids.Count; i++)
{
wSheet.Cells(cell.Row + i, cell.Column).Formula = GetApplicationUrl(ids[i]);
}
}
It is probably slightly less performant but works well enough to be considered as a valid solution.

Reporting system on Aspose.Word / C#

I am currently in need of an idea, I'm developing a software solution and I have to create Words documents from BDD's information.
Everything is fine about informations's use but one point and it's the most important :
On my Word document, I use signets to repeat a table where information is written. One of the column refer to a cost, and since I'm using the signets's system, I don't know where my table end, it can take 1 page as it can take 2500's but I need to calculate at the end of EACH page a total of every row that was written on the current page, and then rewrite this total at the beginning of the next page. So it would be like :
Page 1
nameOfTheItem1 Cost1
nameOfTheItem2 Cost2
nameOfTheItem3 Cost3
nameOfTheItem4 Cost4
TOTAL PAGE 1 : TotalPage1
Page 2
TotalPage1
nameOfTheItem5 Cost5 nameOfTheItem6 Cost6 nameOfTheItem7
Cost7 nameOfTheItem8 Cost8 TOTAL PAGE 2 :
TotalPage2(+TotalPage1)
and this for each page existing for this document.
I'm still looking for a solution by myself, and every help would be great.

It can be done with the mail merge feature of Aspose.Words. The solution is particularly related to the nested mail merge.
You have to arrange the data in a DataSet, in order to make the report appear according to your requirements. For this scenario, arrange in 2 tables. One is "Page" and other is "Item"
Your template document (DOCX) should define the merge fields according the the image below. Note that there is a page break after the table.
The following code will help you to get started. It uses dummy data of course. You can populate with your own data to make it work for you.
MS Word template document that works with this code: Download Template
private void yourMethod()
{
string srcDoc = dataDir + "ItemsTemplate.docx";
string dstDoc = dataDir + "ItemsTemplate_Result.docx";
int totalRecords = 10;
int recordsPerPage = 4;
// Prepare some data
DataSet ds = getData(totalRecords, recordsPerPage);
// Prepare the document in Aspose
Aspose.Words.Document doc = new Aspose.Words.Document(srcDoc);
doc.MailMerge.ExecuteWithRegions(ds);
doc.MailMerge.CleanupOptions = Aspose.Words.Reporting.MailMergeCleanupOptions.RemoveEmptyParagraphs;
doc.Save(dstDoc);
Process.Start(dstDoc);
}
private DataSet getData(int totalRecords, int recordsPerPage)
{
DataSet ds = new DataSet("Dataset");
// Add the page table
System.Data.DataTable pageTable = new System.Data.DataTable("Page");
pageTable.Columns.Add("PageNumber");
pageTable.Columns.Add("PageTotal");
pageTable.Columns.Add("PreviousPageTotal");
// Add the item table
System.Data.DataTable itemTable = new System.Data.DataTable("Item");
itemTable.Columns.Add("ID");
itemTable.Columns.Add("Name");
itemTable.Columns.Add("Cost");
itemTable.Columns.Add("PageNumber");
// Add pages
int iRow = 1, iPage = 1;
while (iRow <= totalRecords )
{
DataRow pageRow = pageTable.NewRow();
pageRow["PageNumber"] = iPage;
pageRow["PageTotal"] = 0;
// Add the items in this page
int iRecordsPerPage = 1;
while (iRow <= totalRecords && iRecordsPerPage <= recordsPerPage)
{
DataRow itemRow = itemTable.NewRow();
itemRow["ID"] = iRow;
itemRow["Name"] = "Item " + iRow;
itemRow["Cost"] = iRow;
itemRow["PageNumber"] = iPage;
pageRow["PageTotal"] = int.Parse(pageRow["PageTotal"].ToString()) + int.Parse(itemRow["Cost"].ToString());
itemTable.Rows.Add(itemRow);
iRow++;
iRecordsPerPage++;
}
pageTable.Rows.Add(pageRow);
// Previous page total
if (iPage == 1)
pageRow["PreviousPageTotal"] = 0; // Always 0 for first page
else
pageRow["PreviousPageTotal"] = pageTable.Rows[iPage - 2]["PageTotal"]; // Get total of previous page
iPage++;
}
ds.Tables.Add(pageTable);
ds.Tables.Add(itemTable);
// We must have relationship for Aspose mail merge to work correctly
ds.Relations.Add(pageTable.Columns["PageNumber"], itemTable.Columns["PageNumber"]);
return ds;
}
Try changing the values of totalRecords and recordsPerPage variables and you will see the data arranged in pages accordingly. Just be sure to keep the recordsPerPage value low, so that it does not exceed single page.
I am a developer evangelist at Aspose.

I am exporting data to existing word template which is .dotx
But the final report does not show the table of contents even though i have added it in code.
My code is as follows
public void ExportToWordUsingTemplate()
{
Aspose.Words.Document doc1 = new Aspose.Words.Document(#"E:/excel/HOVEDMAL Prognoserapporter 2.dotx");
DocumentBuilder docBuilder1 = new DocumentBuilder(doc1);
SkinAPI.ReportAPISoapClient svc = new SkinAPI.ReportAPISoapClient();
SkinAPI.GetReportContextResult myReportContext = svc.GetReportContext(1);
docBuilder1.InsertHtml("<h1 align='left'>" + myReportContext[0].MainReportName + "</h1>");
docBuilder1.InsertTableOfContents("\\o \"1-3\" \\h \\z \\u");
//for (int i = 0; i < myReportContext.Count - 2; i++)
for (int i = 0; i < 5; i++)
{
SkinAPI.GetReportElementGraphDataResult myElementGraphData = svc.GetReportElementGraphData(myReportContext[i].ReportId, myReportContext[i].ElementId);
SkinAPI.GetReportElementDataResult myElementData = svc.GetReportElementData(myReportContext[i].ReportId, myReportContext[i].ElementId, 0, 0, 0); // Three last parameters set to 0, used when fetching drilldown data for tables that support it
docBuilder1.ParagraphFormat.StyleIdentifier = StyleIdentifier.Heading1;
docBuilder1.Writeln(myReportContext[i].ElementHeader);
docBuilder1.ParagraphFormat.StyleIdentifier = StyleIdentifier.BodyText;
// Is there a graph for this element, and has it a datasource other than the main data source as fetched above?
if (myReportContext[i].HasGraph && myReportContext[i].SeparateGraphDataSource)
{
// Is there a text part for this element
if (myReportContext[i].HasText)
{
// The returned string will contain a HTML text.
// Note that the text is connected to a TileId, not an ElementId, meening the text might have been fetched before.
string myElementHTMLDescription = svc.GetReportText(myReportContext[i].TileId);
docBuilder1.InsertHtml(myElementHTMLDescription);
}
}
docBuilder1.InsertBreak(BreakType.PageBreak);
}
doc1.Save(#"E:/excel/HOVEDMAL Prognoserapporter 2_Report.doc");
}

Fastest way to fill DataTable manually in C#

I want to know if someone of you know a faster way to fill a DataTable manually then I do.
Here is what I got, I have a List with about 1.7b entries.
I want to fill this entries as fast as possible into DataTable with one column.
An entry in my list looks like this here {"A2C","DDF","ER","SQ","8G"}
My code need about 7-8 seconds
for (int i = 0; i <= lists.Count; i++)
{
table_list.Rows.Add();
}
for (int a = 0; a < list.Count; a++)
{
table_list.Rows[a][0] = list[a][0] + list[a][1] +
list[a][2] + list[a][3] + list[a][4];
}
As I didn't find any similar question on the board (just questions about how to fill datatable by sql and fill method), I decided to post my question.
Any input is highly appreciated!

i add this DataTable into an sql server database (i do this by SqlBulkCopy)
This is a mistake; the DataTable is pure overhead here. What you should expose is an IDataReader over that data. This API is a bit tricky, but FastMember makes it easier. For example, it sounds like you have 1 column; so consider:
class Foo {
public string ColumnName {get;set;}
}
Now write an iterator block method that converts this from the original list per item:
IEnumerable<Foo> Convert(List<TheOldType> list) {
foreach(var row in list) {
yield return new Foo { ColumnName = /* TODO */ };
}
}
and now create an IDataReader via FastMember on top of that lazy sequence:
List<TheOldType> list
var data = Convert(list);
using(var bcp = new SqlBulkCopy(connection))
using(var reader = ObjectReader.Create(data, "ColumnName"))
{
bcp.DestinationTableName = "SomeTable";
bcp.WriteToServer(reader);
}
This works much better than populating a DataTable - in particular, it avoids populating a huge DataTable. Emphasis: the above is spooling - not buffered.

Why do you create an empty row first, then loop the table again to fill them?
I would use a simple foreach:
var table_list = new DataTable();
table_list.Columns.Add();
foreach(string[] fields in lists)
{
DataRow newRow = table_list.Rows.Add();
newRow.SetField(0, string.Join("", fields));
}
Why do you put all into one field?

Why not use the LoadDataRow method of the DataTable.
// turnoff notifications
table_list.BeginLoadData();
// load each row into the table
foreach(string[] fields in lists)
table_list.LoadDataRow(new object[] { string.Join("", fields) }, false);
// turn notifications back on
table_list.EndLoadData();
Also see: DataTable.LoadDataRow Method http://msdn.microsoft.com/en-us/library/kcy03ww2(v=vs.110).aspx

Export a large data query (60k+ rows) to Excel

I created a reporting tool as part of an internal web application. The report displays all results in a GridView, and I used JavaScript to read the contents of the GridView row-by-row into an Excel object. The JavaScript goes on to create a PivotTable on a different worksheet.
Unfortunately I didn't expect that the size of the GridView would cause overloading problems with the browser if more than a few days are returned. The application has a few thousand records per day, let's say 60k per month, and ideally I'd like to be able to return all results for up to a year. The number of rows is causing the browser to hang or crash.
We're using ASP.NET 3.5 on Visual Studio 2010 with SQL Server and the expected browser is IE8. The report consists of a gridview that gets data from one out of a handful of stored procedures depending on which population the user chooses. The gridview is in an UpdatePanel:
<asp:UpdatePanel ID="update_ResultSet" runat="server">
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btn_Submit" />
</Triggers>
<ContentTemplate>
<asp:Panel ID="pnl_ResultSet" runat="server" Visible="False">
<div runat="server" id="div_ResultSummary">
<p>This Summary Section is Automatically Completed from Code-Behind</p>
</div>
<asp:GridView ID="gv_Results" runat="server"
HeaderStyle-BackColor="LightSkyBlue"
AlternatingRowStyle-BackColor="LightCyan"
Width="100%">
</asp:GridView>
</div>
</asp:Panel>
</ContentTemplate>
</asp:UpdatePanel>
I was relatively new to my team, so I followed their typical practice of returning the sproc to a DataTable and using that as the DataSource in the code behind:
List<USP_Report_AreaResult> areaResults = new List<USP_Report_AreaResult>();
areaResults = db.USP_Report_Area(ddl_Line.Text, ddl_Unit.Text, ddl_Status.Text, ddl_Type.Text, ddl_Subject.Text, minDate, maxDate).ToList();
dtResults = Common.LINQToDataTable(areaResults);
if (dtResults.Rows.Count > 0)
{
PopulateSummary(ref dtResults);
gv_Results.DataSource = dtResults;
gv_Results.DataBind();
(I know what you're thinking! But yes, I have learned much more about parameterization since then.)
The LINQToDataTable function isn't anything special, just converts a list to a datatable.
With a few thousand records (up to a few days), this works fine. The GridView displays the results, and there's a button for the user to click which launches the JScript exporter. The external JavaScript function reads each row into an Excel sheet, and then uses that to create a PivotTable. The PivotTable is important!
function exportToExcel(sMyGridViewName, sTitleOfReport, sHiddenCols) {
//sMyGridViewName = the name of the grid view, supplied as a text
//sTitleOfReport = Will be used as the page header if the spreadsheet is printed
//sHiddenCols = The columns you want hidden when sent to Excel, separated by semicolon (i.e. 1;3;5).
// Supply an empty string if all columns are visible.
var oMyGridView = document.getElementById(sMyGridViewName);
//If no data is on the GridView, display alert.
if (oMyGridView == null)
alert('No data for report');
else {
var oHid = sHiddenCols.split(";"); //Contains an array of columns to hide, based on the sHiddenCols function parameter
var oExcel = new ActiveXObject("Excel.Application");
var oBook = oExcel.Workbooks.Add;
var oSheet = oBook.Worksheets(1);
var iRow = 0;
for (var y = 0; y < oMyGridView.rows.length; y++)
//Export all non-hidden rows of the HTML table to excel.
{
if (oMyGridView.rows[y].style.display == '') {
var iCol = 0;
for (var x = 0; x < oMyGridView.rows(y).cells.length; x++) {
var bHid = false;
for (iHidCol = 0; iHidCol < oHid.length; iHidCol++) {
if (oHid[iHidCol].length !=0 && oHid[iHidCol] == x) {
bHid = true;
break;
}
}
if (!bHid) {
oSheet.Cells(iRow + 1, iCol + 1) = oMyGridView.rows(y).cells(x).innerText;
iCol++;
}
}
iRow++;
}
}
What I'm trying to do: Create a solution (probably client-side) that can handle this data and process it into Excel. Someone might suggest using the HtmlTextWriter, but afaik that doesn't allow for automatically generating a PivotTable and creates an obnoxious pop-up warning....
What I've tried:
Populating a JSON object -- I still think this has potential but I haven't found a way of making it work.
Using a SQLDataSource -- I can't seem to use it to get any data back out.
Paginating and looping through the pages -- Mixed progress. Generally ugly though, and I still have the problem that the entire dataset is queried and returned for each page displayed.
Update:
I'm still very open to alternate solutions, but I've been pursuing the JSON theory. I have a working server-side method that generates the JSON object from a DataTable. I can't figure out how to pass that JSON into the (external) exportToExcel JavaScript function....
protected static string ConstructReportJSON(ref DataTable dtResults)
{
StringBuilder sb = new StringBuilder();
sb.Append("var sJSON = [");
for (int r = 0; r < dtResults.Rows.Count; r++)
{
sb.Append("{");
for (int c = 0; c < dtResults.Columns.Count; c++)
{
sb.AppendFormat("\"{0}\":\"{1}\",", dtResults.Columns[c].ColumnName, dtResults.Rows[r][c].ToString());
}
sb.Remove(sb.Length - 1, 1); //Truncate the trailing comma
sb.Append("},");
}
sb.Remove(sb.Length - 1, 1);
sb.Append("];");
return sb.ToString();
}
Can anybody show an example of how to carry this JSON object into an external JS function? Or any other solution for the export to Excel.

It's easy and efficient to write CSV files. However, if you need Excel, it can also be done in a reasonably efficient way, that can handle 60,000+ rows by using the Microsoft Open XML SDK's open XML Writer.
Install Microsoft Open SDK if you don't have it already (google "download microsoft open xml sdk")
Create a Console App
Add Reference to DocumentFormat.OpenXml
Add Reference to WindowsBase
Try running some test code like below (will need a few using's)
Just Check out Vincent Tan's solution at http://polymathprogrammer.com/2012/08/06/how-to-properly-use-openxmlwriter-to-write-large-excel-files/ ( Below, I cleaned up his example slightly to help new users. )
In my own use I found this pretty straight forward with regular data, but I did have to strip out "\0" characters from my real data.
using DocumentFormat.OpenXml;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Spreadsheet;
...
using (var workbook = SpreadsheetDocument.Create("SomeLargeFile.xlsx", SpreadsheetDocumentType.Workbook))
{
List<OpenXmlAttribute> attributeList;
OpenXmlWriter writer;
workbook.AddWorkbookPart();
WorksheetPart workSheetPart = workbook.WorkbookPart.AddNewPart<WorksheetPart>();
writer = OpenXmlWriter.Create(workSheetPart);
writer.WriteStartElement(new Worksheet());
writer.WriteStartElement(new SheetData());
for (int i = 1; i <= 50000; ++i)
{
attributeList = new List<OpenXmlAttribute>();
// this is the row index
attributeList.Add(new OpenXmlAttribute("r", null, i.ToString()));
writer.WriteStartElement(new Row(), attributeList);
for (int j = 1; j <= 100; ++j)
{
attributeList = new List<OpenXmlAttribute>();
// this is the data type ("t"), with CellValues.String ("str")
attributeList.Add(new OpenXmlAttribute("t", null, "str"));
// it's suggested you also have the cell reference, but
// you'll have to calculate the correct cell reference yourself.
// Here's an example:
//attributeList.Add(new OpenXmlAttribute("r", null, "A1"));
writer.WriteStartElement(new Cell(), attributeList);
writer.WriteElement(new CellValue(string.Format("R{0}C{1}", i, j)));
// this is for Cell
writer.WriteEndElement();
}
// this is for Row
writer.WriteEndElement();
}
// this is for SheetData
writer.WriteEndElement();
// this is for Worksheet
writer.WriteEndElement();
writer.Close();
writer = OpenXmlWriter.Create(workbook.WorkbookPart);
writer.WriteStartElement(new Workbook());
writer.WriteStartElement(new Sheets());
// you can use object initialisers like this only when the properties
// are actual properties. SDK classes sometimes have property-like properties
// but are actually classes. For example, the Cell class has the CellValue
// "property" but is actually a child class internally.
// If the properties correspond to actual XML attributes, then you're fine.
writer.WriteElement(new Sheet()
{
Name = "Sheet1",
SheetId = 1,
Id = workbook.WorkbookPart.GetIdOfPart(workSheetPart)
});
writer.WriteEndElement(); // Write end for WorkSheet Element
writer.WriteEndElement(); // Write end for WorkBook Element
writer.Close();
workbook.Close();
}
If you review that code you'll notice two major writes, first the Sheet, and then later the workbook that contains the sheet. The workbook part is the boring part at the end, the earlier sheet part contains all the rows and columns.
In your own adaptation, you could write real string values into the cells from your own data. Instead, above, we're just using the row and column numbering.
writer.WriteElement(new CellValue("SomeValue"));
Worth noting, the row numbering in Excel starts at 1 and not 0. Starting rows numbered from an index of zero will lead to "Corrupt file" error messages.
Lastly, if you're working with very large sets of data, never call ToList(). Use a data reader style methodology of streaming the data. For example, you could have an IQueryable and utilize it in a for each. You never really want to have to rely on having all the data in memory at the same time, or you'll hit an out of memory limitation and/or high memory utilization.

I would try to use displaytag to display the results. You could set it up display a certain number per page, which should solve your overloading issue. Then, you can set displaytag to allow for an Excel export.

We typically handle this with an "Export" command button which is wired up to a server side method to grab the dataset and convert it to CSV. Then we adjust the response headers and the browser will treat it as a download. I know this is a server side solution, but you may want to consider it since you'll continue having timeout and browser issues until you implement server side record paging.

Almost a week and a half since I began this problem, I've finally managed to get it all working to some extent. I'll wait temporarily from marking an answer to see if anybody else has a more efficient, better 'best practices' method.
By generating a JSON string, I've divorced the JavaScript from the GridView. The JSON is generated in code behind when the data is populated:
protected static string ConstructReportJSON(ref DataTable dtResults)
{
StringBuilder sb = new StringBuilder();
for (int r = 0; r < dtResults.Rows.Count; r++)
{
sb.Append("{");
for (int c = 0; c < dtResults.Columns.Count; c++)
{
sb.AppendFormat("\"{0}\":\"{1}\",", dtResults.Columns[c].ColumnName, dtResults.Rows[r][c].ToString());
}
sb.Remove(sb.Length - 1, 1); //Truncate the trailing comma
sb.Append("},");
}
sb.Remove(sb.Length - 1, 1);
return String.Format("[{0}]", sb.ToString());
}
Returns a string of data such as
[ {"Caller":"John Doe", "Office":"5555","Type":"Incoming", etc},
{"Caller":"Jane Doe", "Office":"7777", "Type":"Outgoing", etc}, {etc} ]
I've hidden this string by assigning the text to a Literal in the UpdatePanel using:
<div id="div_JSON" style="display: none;">
<asp:Literal id="lit_JSON" runat="server" />
</div>
And the JavaScript parses that output by reading the contents of the div:
function exportToExcel_Pivot(sMyJSON, sTitleOfReport, sReportPop) {
//sMyJSON = the name, supplied as a text, of the hidden element that houses the JSON array.
//sTitleOfReport = Will be used as the page header if the spreadsheet is printed.
//sReportPop = Determines which business logic to create a pivot table for.
var sJSON = document.getElementById(sMyJSON).innerHTML;
var oJSON = eval("(" + sJSON + ")");
// DEBUG Example Test Code
// for (x = 0; x < oJSON.length; x++) {
// for (y in oJSON[x])
// alert(oJSON[x][y]); //DEBUG, returns field value
// alert(y); //DEBUG, returns column name
// }
//If no data is in the JSON object array, display alert.
if (oJSON == null)
alert('No data for report');
else {
var oExcel = new ActiveXObject("Excel.Application");
var oBook = oExcel.Workbooks.Add;
var oSheet = oBook.Worksheets(1);
var oSheet2 = oBook.Worksheets(2);
var iRow = 0;
var iCol = 0;
//Take the column names of the JSON object and prepare them in Excel
for (header in oJSON[0])
{
oSheet.Cells(iRow + 1, iCol + 1) = header;
iCol++;
}
iRow++;
//Export all rows of the JSON object to excel
for (var r = 0; r < oJSON.length; r++)
{
iCol = 0;
for (c in oJSON[r])
{
oSheet.Cells(iRow + 1, iCol + 1) = oJSON[r][c];
iCol++;
} //End column loop
iRow++;
} //End row
The string output and the JavaScript 'eval' parsing both work surprisingly fast, but looping through the JSON object is a little slower than I'd like.
I believe that this method would be limited to around 1 billion characters of data -- maybe less depending how memory testing works out. (I've calculated that I'll probably be looking at a maximum of 1 million characters per day, so that should be fine, within one year of reporting.)

How to write this in better way?

Let's look at this code:
IList<IHouseAnnouncement> list = new List<IHouseAnnouncement>();
var table = adapter.GetData(); //get data from repository object -> DataTable
if (table.Rows.Count >= 1)
{
for (int i = 0; i < table.Rows.Count; i++)
{
var anno = new HouseAnnouncement();
anno.Area = float.Parse(table.Rows[i][table.areaColumn].ToString());
anno.City = table.Rows[i][table.cityColumn].ToString();
list.Add(anno);
}
}
return list;
Is it better way to write this in less code and better fashion (must be :-) )? Maybe using lambda (but let me know how)?
Thanks in advance!

Just FYI, you're never adding the new HouseAnnouncement to your list, and your loop will never execute for the last row, but I'm assuming those are errors in the example rather than in your actual code.
You could do something like this:
return adapter.GetData().Rows.Cast<DataRow>().Select(row =>
new HouseAnnouncement()
{
Area = Convert.ToSingle(row["powierzchnia"]),
City = (string)row["miasto"],
}).ToList();
I usually go for readability over brevity, but I feel like this is pretty readable.
Note that while you could still cache the DataTable and use table.powierzchniaColumn in the lambda, I eliminated that so that you didn't use a closure that wasn't really necessary (closures introduce substantial complexity to the internal implementation of the lambda, so I avoid them if possible).
If it's important to you to keep the column references as they are, then you can do it like this:
using (var table = adapter.GetData())
{
return table.Rows.Cast<DataRow>().Select(row =>
new HouseAnnouncement()
{
Area = Convert.ToSingle(row[table.powierzchniaColumn]),
City = (string)row[table.miastoColumn],
}).ToList();
}
This will add complexity to the actual IL that the compiler generates, but should do the trick for you.

You could do something like this in Linq:
var table = adapter.GetData();
var q = from row in table.Rows.Cast<DataRow>()
select new HouseAnnouncement()
{ Area = float.Parse(row[table.areaColumn].ToString()),
City = row[table.cityColumn].ToString()
};
return q.ToList();

Your "if statement" is not necessary. Your "for loop" already takes care of that case.
Also, your "for loop" will not execute when the number of your Table Rows is 1. This seems like a mistake, and not by design, but I could be wrong. If you want to fix this, just take out the "-1":
for (int i = 0; i < table.Rows.Count; i++)

Well, for one thing, you appear to have an off-by-one error:
for (int i = 0; i < table.Rows.Count - 1; i++)
{
}
If your table has three rows, this will run while i is less than 3 - 1, or 2, which means it'll run for rows 0 and 1 but not for row 2. This may not be what you intend.

Can't go much simpler that one for-loop and no if-statements:
var table = adapter.GetData(); //get data from repository object -> DataTable
IList<IHouseAnnouncement> list = new List<IHouseAnnouncement>(table.Rows.Count);
for (int i = 0; i < list.Length; i++)
{
list[i] = new HouseAnnouncement();
list[i].Area = float.Parse(table.Rows[i][table.areaColumn].ToString());
list[i].City = table.Rows[i][table.cityColumn].ToString();
}
return list;
It takes more characters than linq-version, but is parsed faster by programmer's brain. :)

Readability is, to me, preferable to being succinct with your code--as long as performance is not a victim. Also, I am sure that anyone who later has to maintain the code will appreciate it as well.
Even when I am maintaining my own code, I don't want to look at it, say a couple of months later, and think "what the hell was I trying to accomplish"

I might do something like this:
var table = adapter.GetData(); //get data from repository object -> DataTable
return table.Rows.Take(table.Rows.Count-1).Select(row => new HouseAnnouncement() {
Area = float.Parse(row[table.powierzchniaColumn].ToString()),
City = row[table.miastoColumn].ToString()
}).ToList();