Develop Reference

Filtering from list of C# or LINQ

I am trying to filter from attachList the taxheaderID, it comes from my database which is structured as such.
public int attachmentID { get; set; }
public int headerID { get; set; }
public string uploadedfilename { get; set; }
public string originalfilename { get; set; }
public string foldername { get; set; }
Here is the code that gets data from the database:
public JsonResult GetAllAttach()
{
using (car_monitoringEntities contextObj = new car_monitoringEntities())
{
var attachList = contextObj.car_taxcomputationattachment.ToList();
return Json(attachList, JsonRequestBehavior.AllowGet);
}
}
These are my attempts:
attachList
.Select(x => x.headerID)
.Where(x => x == x)
.Take(1);
and:
attachList = attachList
.Where(al => attachList
.Any(alx => al.taxheaderID == alx.headerID
&& al.headerID == alx.headerID));
The problem is I want to parse multiple attach on a single headerID or filter them base on headerID. For example:
Problem to fix:
This is the table
Desired output:
Combined
data table:
data table
data table 2
Here is the actual solution that was made to get the output, but my coworker told me that it is not a good practice that's why I'm trying to filter it in the function itself. apologies for the trouble, thanks!
<div ng-repeat="att in attach|filter:{headerID:header.headerID}:true">
{{att.uploadedfilename}} <br />
</div>

To get attachments by Id
public JsonResult GetAllAttach(int headerId)
{
using (car_monitoringEntities contextObj = new car_monitoringEntities())
{
var attachList = contextObj.car_taxcomputationattachment
.Where(x => x.headerID == headerId)
.ToList();
return Json(attachList, JsonRequestBehavior.AllowGet);
}
}
If you want to have all data in one JSON result, then you need to create a nested view model.

Assuming you have the header id on which you want to filter in a local variable, you are almost correct
int headerIdToFind = 19;
// think of x as a local variable inside a foreach loop which
// iterates over each item in the attachList (it does not exist
// outside the where method)
// this is what you got wrong when you compared the item to itself
var filteredAttach = attachList.Where(x => x.headerId = headerIdToFind);
// if you want to select only some properties based on header id
// you can use select to project those properties
var filteredAttach = attachList.Where(x => x.headerId = headerIdToFind).
Select(x => new {x.attachmentId, x.folderName});
// based on last image, you only want to select (project) header id and the
// filename. so you do not need where (filter) at all
// you can put all the properties you need in the select clause
var filteredAttach = attachList.Select(x => new {x.headerId, x.attachmentId});
// you can enumerate the filtered attach list of convert it into a list
var filteredAttach = filteredAttach.ToList();

C# MongoDB LINQ: Cannot query nested list

I'm trying to query a MongoDB collection using official C# driver. Here's the object structure I've created:
IMongoDatabase db = mongoClient.GetDatabase("appdb");
IMongoCollection<MusicFile> musicfiles = db.GetCollection<MusicFile>("files");
public class MusicFile
{
public ObjectId Id { get; set; }
public string Name { get; set; }
public IList<Comment> Comments { get; set; }
}
public class Comment
{
public string Text { get; set; }
}
This is the query I'm trying to get any MusicFile objects that contains a Comment object with property Text = "Comment1":
musicfiles.AsQueryable().Where(f => f.Comments != null && f.Comments.Any(c => c.Text == "Comment1")).ToList();
I can't get this query to work, it always returns an empty list. I also tried this, which too didn't work:
musicfiles.Find(f => f.Comments.Any(c => c.Text == "Comment1")).ToList()
But, if I get the complete collection is memory, the query works:
musicfiles.Find(FilterDefinition<MusicFile>.Empty).ToList().Where(f => f.Comments != null && f.Comments.Any(c => c.Text == "Comment1")).ToList();
This seems like a very inefficient way to query. Any suggestions?

OK. I'm back at home. Try this:
var musicFilter = Builders<MusicFile>.Filter;
var commentFilter = Builders<Comment>.Filter;
var files = musicfiles
.Find(
musicFilter.NE(m => m.Comments, null)
& musicFilter.ElemMatch(m => m.Comments, commentFilter.Eq(c => c.Text, "Comment1"))
)
.ToEnumerable()
.ToList();
Note I call .ToList() because, otherwise, if you iterate through files multiple times, you'll get multiple calls to the database for the same objects.

Issue displaying LINQ query results in a grid in C#

I received some help here with the following LINQ query, but am still struggling with it. The result I'm trying to obtain is to display some attributes and their values from an xml file in a DataGridView control. I'm calling my method from a button click and am trying to pass back the list for display in the grid. Here is an example of the row:
<z:row CenterCode="JAX" CenterName="Jacksonville" Version="1.0" NextExport="66742" NextImport="29756" LastImportTime="2015-06-10T14:48:33" FtpProxyServer="" FtpUserName="" FtpPassword="" ResetImportID="False"/>
Here is the method:
public static List<string[]> MonitorCounts(string upperLimit)
{
// Load xml
XDocument xmldoc = XDocument.Load(#"c:\XML\Configuration.xml");
XNamespace z = "#RowsetSchema";
Int32 limit = Convert.ToInt32(upperLimit);
var elementQuery = xmldoc.Descendants(z + "row").Where(e => (long?)e.Attribute("NextExport") > limit | (long?)e.Attribute("NextImport") > limit);
var attributes = elementQuery.Select(e => e.Attributes().Select(a => new KeyValuePair<string, string>(a.Name.LocalName, (string)a)).ToList()).ToList();
return attributes;
}
My questions are how to select only specific attributes and values in attributes. If I do something like this:
var attributes = elementQuery.Select(e => e.Attributes("CenterName").Select(a => new KeyValuePair<string, string>(a.Name.LocalName, (string)a)).ToList()).ToList();
then this is returned:
[0] = {[CenterName, Jacksonville]}
I need to select this and 4 others. I'm also getting a convrsion error - Cannot implicitly convert type 'System.Collections.Generic.List<System.Collections.Generic.List<System.Collections.Generic.KeyValuePair<string,string>>>' to 'System.Collections.Generic.List<string[]>. Appreciate any pointers to help me along.

You can use an anonymous type:
var attributes =
elementQuery.Select(e => new
{
CenterName = (string)e.Attribute["CenterName"],
Version = (string)e.Attribute["Version"],
// more attributes
}).ToList();
You can't however return this from the method in a useful way. So if you really need both the attribute name and the attribute value as strings, try this approach instead:
var attributes =
elementQuery.Select(e => new []
{
Tuple.Create("CenterName", (string)e.Attribute["CenterName"]),
Tuple.Create("Version", (string)e.Attribute["Version"]),
// more attributes
}).SelectMany(x => x).ToList();
The return type of your method now has to be List<Tuple<string, string>>.
And finally, if you actually need a List<string[]> as the return type, use this code:
var attributes =
elementQuery.Select(e => new []
{
new [] { "CenterName", (string)e.Attribute["CenterName"] },
new [] { "Version", (string)e.Attribute["Version"] },
// more attributes
}).SelectMany(x => x).ToList();

I solved my own problem. Here is what I did:
Created a class for the attributes needed:
public class dataRow
{
public string CenterName { get; set; }
public string CenterCode { get; set; }
public string NextImport { get; set; }
public string NextExport { get; set; }
public string LastImportTime { get; set; }
}
Selected the results into it:
List<dataRow> dataRows = elementQuery.Select( e => new dataRow
{ CenterName = (string)e.Attribute("CenterName"),
CenterCode = (string)e.Attribute("CenterCode"),
NextImport = (string)e.Attribute("NextImport"),
NextExport = (string)e.Attribute("NextExport"),
LastImportTime = (string)e.Attribute("LastImportTime") }).ToList();
Changed my method to return the correct object:
public static List<dataRow> MonitorCounts(string upperLimit)
Set my grids datasource to the method return:
dataGridView1.DataSource = xmlProcessing.MonitorCounts(tbxUpperLimit.Text.ToString());
return dataRows;

Building XML using Linq from a List<CustomClass>

I'm just trying to understand Linq and I am trying to do something that seems very simple, but I can't get it to output the way I would like. I have been stuck on this for days trying various different methods I just can't get it right.
So I have a class EarObs, it has members: eventID, icaoId, frm, sta, db.
I'm trying to build an XML document from a List. I want the XML document to look like so:
<EarObs EventId = "123456789">
<icao icaoID = "0001">
<frm frm = "01">
<sta sta = "00">
<db>87</db>
<hz>99</hz>
</sta>
<sta station = "01">
<db>79</db>
<hz>99</hz>
</sta>
</frm>
<frm frm = "02">
................
</frm>
</icao>
</EarObs>
And this would continue all the way down keeping the same order if there was more than one frame or more than one code etc.
So this is what I have been trying most recently but it still does not output they way I would like, Obs get repeated and I do not know where I am going wrong.
string eventGUID = "eventGUID";
List<EarObs> frameObsList = new List<EarObs>();
for (int frm = 2; frm > 0; frm--)
{
for (int sta = 5; sta > 0; sta--)
{
frameObsList.Add(new EarObs("KAPF", eventGUID, frm, sta, 85 + sta, 99 + sta));
cnt++;
}
}
String eventID = obsList.First().EventGUID;
List<EarObs> distinctApts =
obsList
.GroupBy(p => p.IcaoId)
.Select(g => g.First())
.ToList();
XElement xElement = new XElement("EarObs", new XAttribute("eventID", eventID),
from ea in distinctApts
orderby ea.IcaoId
select new XElement("icao", new XAttribute("code", ea.IcaoId),
from eb in obsList
where ea.IcaoId == eb.IcaoId
orderby eb.Frm
select new XElement("frm", new XAttribute("frm", eb.Frm),
from ec in obsList
where eb.Frm == ec.Frm
orderby ec.Sta
select new XElement("sta", new XAttribute("sta", ec.Sta),
new XElement("db", ec.Db),
new XElement("hz", ec.Hz)))));
Using this code I get an xml document that repeats the frame once for each station. This is not correct. I feel like this is easily done sequentially, but I'm trying to learn and this seems just so simple that I should be able to do it in Linq. I need each element in the List to only be represented in the XML document once. How do I go about this?
I would also like to expand it so that it can handle multiple eventId's as well, but that is not as important as getting the XML structure right. Any help would be much appreciated, I haven't been able to find too many example of creating an XML including the filtering of the elements using linq, most examples seem to have the List all ready structured before they create the XML.

Since you have a custom class, EarObs why not define Xml attributes to your object and serialize the object using the XmlSerlizer class? This way, you can continue use Linq on your objects, and also output your objects.
e.g. Below is a team, with players on it.
[XmlRoot("root")]
public class Team
{
private List<Player> players = new List<Player>();
[XmlElement("player")]
public List<Player> Players { get { return this.players; } set { this.players = value; } }
// serializer requires a parameterless constructor class
public Team() { }
}
public class Player
{
private List<int> verticalLeaps = new List<int>();
[XmlElement]
public string FirstName { get; set; }
[XmlElement]
public string LastName { get; set; }
[XmlElement]
public List<int> vertLeap { get { return this.verticalLeaps; } set { this.verticalLeaps = value; } }
// serializer requires a parameterless constructor class
public Player() { }
}
Once I create a team, with some players on it, I just have to do:
Team myTeamData = new Team();
// add some players on it.
XmlSerializer deserializer = new XmlSerializer(typeof(Team));
using (TextReader textReader = new StreamReader(#"C:\temp\temp.txt"))
{
myTeamData = (Team)deserializer.Deserialize(textReader);
textReader.Close();
}
The output will look like this:
<?xml version="1.0" encoding="utf-8"?>
<root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<player>
<FirstName>dwight</FirstName>
<LastName>howard</LastName>
<vertLeap>1</vertLeap>
<vertLeap>2</vertLeap>
<vertLeap>3</vertLeap>
</player>
<player>
<FirstName>dwight</FirstName>
<LastName>howard</LastName>
<vertLeap>1</vertLeap>
</player>
</root>

The easiest way is to create a set of classes to handle the serialization like so;
public class sta
{
public int db { get; set; }
public int hz { get; set; }
[XmlAttribute()]
public string station { get; set; }
}
public class frm
{
[XmlAttribute("frm")]
public string frmID { get; set; }
[XmlElement("sta")]
public List<sta> stas { get; set; }
}
public class icao
{
[XmlAttribute]
public string icaoID { get; set; }
[XmlElement("frm")]
public List<frm> frms { get; set; }
}
public class EarObs
{
[XmlAttribute]
public string EventId { get; set; }
[XmlElement("icao")]
public List<icao> icaos { get; set; }
}
and you can use the xml serializer to serialize/deserialize. The following serializes to the structure identical to what you have;
XmlSerializer serializer = new XmlSerializer(typeof(EarObs));
EarObs obs = new EarObs() { EventId = "123456789" };
obs.icaos = new List<icao>();
obs.icaos.Add(new icao() { icaoID = "0001" });
obs.icaos[0].frms = new List<frm>();
obs.icaos[0].frms.Add(new frm() { frmID = "01" });
obs.icaos[0].frms[0].stas = new List<sta>();
obs.icaos[0].frms[0].stas.Add(new sta() { station = "00", db = 87, hz = 99 });
obs.icaos[0].frms[0].stas.Add(new sta() { station = "01", db = 79, hz = 99 });
obs.icaos[0].frms.Add(new frm() { frmID = "02" });
using (StringWriter s = new StringWriter())
{
serializer.Serialize(s, obs);
string test = s.ToString();
}
Outputs;
<?xml version="1.0" encoding="utf-16"?>
<EarObs xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" EventId="123456789">
<icao icaoID="0001">
<frm frm="01">
<sta station="00">
<db>87</db>
<hz>99</hz>
</sta>
<sta station="01">
<db>79</db>
<hz>99</hz>
</sta>
</frm>
<frm frm="02" />
</icao>
</EarObs>
Now, while this seems like a lot of trouble to go to, it's possible to use the xsd.exe tool (comes with the framework I believe), to automatically create a set of classes that match any given xml file, although it does use an intermediary xsd file (painless though). You can find out how here; How to generate .NET 4.0 classes from xsd?

C# Linq to XML - Parse Nested Object List

I currently have a XML file format that goes something like this (whitespace and ellipses added for readability):
<root>
<Module> //Start with list of Modules
<ModuleParams>
</ModuleParams>
</Module>
...
<DetectLine> //Now a list of DetectLines
<DetectLineParams>
</DetectLineParams>
<Channels> //List of Channels embedded in each DetectLine
<Channel>
<ChannelParams>
</ChannelParams>
</Channel>
...
</Channels>
</DetectLine>
...
</root>
Classes structured as follows:
public class Module
{
public ModuleParams { get; set; }
}
public class DetectLine
{
public DetectLineParams { get; set; }
public List<Channel> Channels { get; set; }
}
public class Channel
{
public ChannelParams { get; set; }
}
The list of Modules and DetectLines are easy to parse with Linq to XML. However, parsing the Channel list for each DetectLine is not as apparent to me. Can this even be done with Linq to XML? I would prefer not having to restructure things to work with a XMLSerializer.
Initial Code (openXML is a OpenFileDialog. Already checked for good filename):
List<Module> myModules;
List<DetectLine> myDetectLines;
XDocument config = XDocument.Load(openXML.FileName);
myModules =
(from myElements in config.Descendants("Module")
select new Module()
{
ModuleParam1 = (string)myElements.Element("ModuleParam1"),
ModuleParam2 = (string)myElements.Element("ModuleParam2"),
...
}).ToList<Module>();
myDetectLines =
(from myElements in config.Descendants("DetectLine")
select new DetectLine()
{
DetectLineParam1 = (string)myElements.Element("ModuleParam1"),
DetectLineParam2 = (string)myElements.Element("ModuleParam2"),
...
// ?? Add Channels list here somehow...
}).ToList<DetectLine>();

With
XElement detectLine = XElement.Parse(#"<DetectLine>
<DetectLineParams>
</DetectLineParams>
<Channels>
<Channel>
<ChannelParams>
</ChannelParams>
</Channel>
...
</Channels>
</DetectLine>
");
you can do e.g.
DetectLine dl1 = new DetectLine() {
DetectLineParams = ...,
Channels = (from channel in detectLine.Element("Channels").Element("Channel")
select new Channel() {
ChannelParams = new ChannelParams() { ... = channel.Element("ChannelParams").Value }
}).ToList();
We really need to see more of the concrete C# class code to spell out how to set up the complete query.
[edit]
To fit in with the code you have now posted:
myDetectLines =
(from myElements in config.Descendants("DetectLine")
select new DetectLine()
{
DetectLineParam1 = (string)myElements.Element("ModuleParam1"),
DetectLineParam2 = (string)myElements.Element("ModuleParam2"),
...
Channels = (from channel in myElements.Element("Channels").Element("Channel")
select new Channel() {
ChannelParams = new ChannelParams() { ... = channel.Element("ChannelParams").Value }
}).ToList();
}).ToList<DetectLine>();