Develop Reference

Use C# Linq Lambda to combine fields from two objects into one, preferably without anonymous objects

I have a class setup like this:
public class Summary
{
public Geometry geometry { get; set; }
public SummaryAttributes attributes { get; set; }
}
public class SummaryAttributes
{
public int SERIAL_NO { get; set; }
public string District { get; set; }
}
public class Geometry
{
public List<List<List<double>>> paths { get; set; }
}
and i take a json string of records for that object and cram them in there like this:
List<Summary> oFeatures = reportObject.layers[0].features.ToObject<List<Summary>>();
my end goal is to create a csv file so i need one flat List of records to send to the csv writer i have.
I can do this:
List<SummaryAttributes> oAtts = oFeatures.Select(x => x.attributes).ToList();
and i get a nice List of the attributes and send that off to csv. Easy peasy.
What i want though is to also pluck a field off of the Geometry object as well and include that in my final List to go to csv.
So the final List going to the csv writer would contain objects with all of the fields from SummaryAttributes plus the first and last double values from the paths field on the Geometry object (paths[0][0][first] and paths[0][0][last])
It's hard to explain. I want to graft two extra attributes onto the original SummaryAttributes object.
I would be ok with creating a new SummaryAttributesXY class with the two extra fields if that's what it takes.
But i'm trying to avoid creating a new anonymous object and having to delimit every field in the SummaryAttributes class as there are many more than i have listed in this sample.
Any suggestions?

You can select new anonymous object with required fields, but you should be completely sure that paths has at least one item in each level of lists:
var query = oFeatures.Select(s => new {
s.attributes.SERIAL_NO,
s.attributes.District,
First = s.geometry.paths[0][0].First(), // or [0][0][0]
Last = s.geometry.paths[0][0].Last()
}).ToList()

Got it figured out. I include the X and Y fields in the original class definition. When the json gets deserialized they will be null. Then i loop back and fill them in.
List<Summary> oFeatures = reportObject.layers[0].features.ToObject<List<Summary>>();
List<Summary> summary = oFeatures.Select(s =>
{
var t = new Summary
{
attributes = s.attributes
};
t.attributes.XY1 = string.Format("{0} , {1}", s.geometry.paths[0][0].First(), s.geometry.paths[0][1].First());
t.attributes.XY2 = string.Format("{0} , {1}", s.geometry.paths[0][0].Last(), s.geometry.paths[0][1].First());
return t;
}).ToList();
List<SummaryAttributes> oAtts = summary.Select(x => x.attributes).ToList();

C# Is it possible to model bind multiple options?

I have a dropdown on which you can select multiple options.
The code for this dropdown is:
How can i bind multiple 'devices' in C# so that when this dropdown is loaded
model binding will automatically select all options which are passed into the view?

For your case you should use another helper - #Html.ListBoxFor it should generate select element with multiple attribute.
//note that i use MaintanceDevices property
#Html.ListBoxFor(x => x.MaintanceDevices, new SelectList(Model.Devises, "ID", "Description"), new { #class = "multiselect form-control"})
Also, don't set id attribute in helper. It's better to create another property in your ViewModel:
public List<int> MaintanceDevices { get; set; }
Populate it in Controller and MVC automatically generate right markup for your select element bind in on form POST.

In this situations, i would do the following inside the viewmodel
public string Devices { get; set; }
List<int> innerList;
public List<int> List
{
get
{
if (this.innerList == null)
{
if (string.IsNullOrEmpty(this.Devices))
{
this.innerList = this.Devices.Split(',').Select(x => int.Parse(x)).ToList();
}
else
{
this.innerList = new List<int>();
}
}
return this.innerList;
}
}
Where Devices is the binded property with the dropdown, which it returns all items separated by ,.
When you try to access List it will separate the items and return it as a List<int>.
And i'm parsing it to int because normally i see int's as ID's
But i'm looking forward for a better option.
PS
I do this when working with Select2

Devices property in your model should be a list of Ids (where is a simple type like int or a string) and not a list of Device models (Since you are using new SelectList(Model.Devices, "ID", "Description") in the Helper it is i see that Model.Devices is a collection of complex object)
So your model should look like:
public List<Device> AvailableDevices { get;set; }
public List<string> Devices { get;set; }
and the Helper should be
#Html.ListBoxFor(m=>m.Devices,new SelectList(Model.AvailableDevices , "ID", "Description"))
or
#Html.DropDownListFor(m=>m.Devices,new SelectList(Model.AvailableDevices , "ID", "Description", new {multiple="multiple"})
post action should receive either a List<string> as an argument or a full model:
[HttpPost]
public ActionResult Submit(List<string> devices)
or
[HttpPost]
public ActionResult Submit(YourModel model)
//where YourModel model is the same type that you are using to render your view

MVC DropDownListfor() Basics

I have a Model which consist of Employees information. In my model there is a property called City which define the city of Employee in which he lives. The propery is shown below
public string City{get;set;}
Now I have a view which contains a form which will be filled by a employee to register. I want to use a dropdownlist for selecting cities. I think the below code will be used for dropdown as i discovered. My model name is Employee.
#Html.DropDownListFor(m=>m.City,new SelectList())
Please tell me that "is there any way to define the options for dropdownlist in SelectList() method directly Like ... in html?"
If not, where should i define the class for this drop down, where to call and where to render.I don't know where to define values? I am very confused because this is mvc and we have to seperate concern and i think we cannot define anything at anywhere?
Thanks in advance..

You have at least two options:
1.) Add a list, array, or any other collection type of cities to your model
2.) Add a SelectList property to your model
Option 1 can be something as simple as an array of strings, or can be, say, an IEnumerable of City objects. You would then need to transform this property to a collection of SelectListItem objects in the view as part of the DropDownList binding.
Option 2 has the advantage of being capable of direct binding to the DropDownList, but requires that you construct the list within the action method.
Then end result is the same, it's just a matter of how pedantic you want to be about SoC.
For example (assuming you add a property called Cities):
#Html.DropDownListFor(m=>m.City, Model.Cities.Select(city => new SelectListItem()
{
Text = city,
Value = city,
Selected = city == Model.City
})
EDIT:
To answer your comment, I have to make some assumptions. I will assume you have a model called EmployeeModel. This model has a property, City, that is a plain string. So, this is a partial of your model, as I assume it to be:
public class EmployeeModel
{
public string City { get; set; }
// ... other properties ...
}
So, if you need to add a property for binding to your dropdown, you would do one of the following:
public class EmployeeModel
{
public string City { get; set; }
public IEnumerable<string> Cities { get; set; }
// ... other properties ...
}
or
public class EmployeeModel
{
public string City { get; set; }
public SelectList Cities { get; set; }
// ... other properties ...
}
This new property will contain the list of cities that you allow your user(s) to pick from.
If you choose the first option, you load the IEnumerable from your datastore, and then use the first example above in your view, which uses LINQ to project each string in the Cities property into a new SelectListItem object.
If you go with the second option, you build a SelectList in the action prior to passing the model to the view. This isn't terribly difficult, as the class provides a constructor that takes an IEnumerable (your list of cities) and the "selected value," which will be the City property (see http://msdn.microsoft.com/en-us/library/dd460123%28v=vs.108%29.aspx). Your code would look something like:
model.Cities = new SelectList(GetCities(), model.City);
This, of course, assumes you have a helper method (GetCities()) to load your cities from wherever they are stored. Your view then would have something like this:
#Html.DropDownListFor(m=>m.City, model.Cities)
The view engine then uses these SelectListItems to build the <select> element and it's <option> elements.

You could have this in your model, it's quickly achieved, although I wouldn't recommend it:
public class Place
{
public string City{get;set;}
public SelectListItem[] Cities()
{
return new SelectListItem[2] { new SelectListItem() { Text = "London" }, new SelectListItem() { Text = "New York" } };
}
}
...and your view
#Html.DropDownListFor(m => m.City, Model.Cities())
I think the best place for something like this (but is a little more complicated) is your own htmlhelper and usage could look something like:
#html.CityDropDownFor(m => m.City)
You could cache the cities nicely and it keeps data and UI work out of your models.
If you want to learn more about creating your own helpers, I'd suggest a bit of a [read up].1

How construct a Type, To hold two 'types' of data , to be sent As a Single Parameter

I need to implement this approach - two kinds of data sent as one set of parameters in a single Type - so that one type will hold those two parameters. That way I will be able to pass that Type to be processed by some method.
the first data item is:
Columns to be displayed , named: displayed
the second data item:
A copy (or only a portion) of that Columns displayed, as it has the same source, only these columns will not be displayed... in other words, Columns to omit, so I've named it: omitted
both are of a type Columns that I named - SelectedColumns
public class SelectedcColoumns
{
public enum renederingMode
{
Displayed,
omitted
}
public class omitted
{
}
public class displayed
{
}
}
As the request for that SetOfColumns to be displayed is done by choosing table-name. So the Column class as data to be displayed varies based on the user choice the available source For SelectedColumns to choose from, is as shown below:
public class tableNames
{
public static readonly string tblCustomers = "tblCustomers";
public static readonly string tblProducts = "tblProducts";
}
public class TblColumns
{
public class tblCustomers
{
public const string custID = "custID",
Name = "Name",
Phone = "Phone";
Email = "Email";
}
public class tblProducts
{
public const string PrudctID = "PrudctID ",
PrudctName = "PrudctID",
PrudctCategory = "PrudctCategory";
}
...etc'
}
When the user selects a set of tables Columns ... from any table user could, in this example.. choose either Customers or Products columns (e.g. SelectedColumns - is tblCustomers Columns), I then need to have another list, of those that the user selected to omit (not to display) from all of available table Columns.
Say the user chose to have Table Customers as a table. He chose to omit tblCustomers.custID + tblCustomer.Email because he only needs the name and phone to be displayed.
The problem I've encountered is while having these parameters in my reach (table name + columns to omit), How could I send it to process (passing it as One Parameter)? So that is why I've created a dedicated class, to hold this Type as sent parameter: all columns + omitted Columns in one piece.
This is where I am currently stuck; I need to know how to use it to build / construct the parameter out of user selection.
public class SelectedColoumns
{
public enum renederingMode
{
Displayed,
omitted
}
public class omitted
{
List<string> omitCols_ListStr = new List<string>();
}
public class displayed
{
List<string> dispCols_ListStr = new List<string>();
}
}
In this part, I retrieve list of Columns through reflection as the supplier of data, via the following method:
Get any Nested Class-Fields, As List<string>, By a nested class-name and it's parent - Type.
public static List<string> anyNestedClassFiledsAsListByType<ClassToReturnOneOfitsNested_Fields>(string NetedClassName)
{
var RetNestedClassFildsListValues = typeof(ClassToReturnOneOFitsNested).GetNestedTypes()
.First(t => String.Compare(t.Name, NetedClassName, true) == 0).GetFields(BindingFlags.Public | BindingFlags.Static)
.Where(f => f.FieldType == typeof(string)).Select(f => (string)f.GetValue(null)).ToList();
return RetNestedClassFildsListValues;
}
so to produce this I could use the method above Like that
var TableColumns_ALL =
anyNestedClassFldsAsListByType<TblColumns>(tableNames.tblCustomers);
My question is related to the class that needs to send TableColumns_ALL + the selected Columns to omit to be then processed by renderSelectedTable() below.
So it's even more basic than the complexity of reflection, but still some how i do not know the popper way to construct, the SelectedColumns class, so it will accommodate and format the structure of this new data type that will be sent as a parameter the method is something like this.
public void renderSelectedTable(SelectedColoumns CurrentUserSelectedCols)
{
StringBuilder NwTRLoopSB = new StringBuilder();
string curRowStyle= string.Empty,
nwLine = Environment.NewLine + "\t\t\t",
BaseTemplateTD = string.Empty;
NwTRLoopSB.Append(
string.Format(
"<table id='tbl_Settings' cellspacing='0' border='1'><tr id='TR_headers'{0}>{1}",
curRowStyle,
nwLine
)._Dhtml_DoubleQoutes()
);
foreach (var Item in SelectedListStr.Select((Val, counter) => new { Value = Val, Index = counter }))
{
curRowStyle = Lsts.DynamicStyle_Generator(Item.Index);
if(Lsts.ExcludeColumns(Item.Value, OmittedCols))
{
BaseTemplateTD = string.Format("<td>{0}</td>{1}", Item.Value, nwLine)._Dhtml_DoubleQoutes();
NwTRLoopSB.Append(BaseTemplateTD);
}
}///ENd TR cells generator Section
NwTRLoopSB.Append("</tr></table>");
return NwTRLoopSB.ToString();
}

I would approach it this way:
public class Column{
public string Name { get; set; }
public bool Visible { get; set; }
}
public class Grid{
public List<Column> Columns { get; set; }
}
So the I could easily define my full table with either visible or ommited columns.
In the OP's example:
public class SelectedColumns
{
//instead of the enum you would have boolean in the column type "Visible" (whether is shown or not)
public enum renederingMode
{
Displayed,
omitted
}
// instead of both these you would have a List o Column types that have a name AND a boolean, so you have your List<string> and a boolean to indicate whether it is visible or ommited. Well at least that's how I understood it.
public class ommited
{
}
public class displayed
{
}
}

so.. first.. a design note: Given a list of columns.. you will either display a column, or not display a column.. there are no other options where visibility is concerned. So you really only need to pass in a single list of EITHER the columns to display, OR the columns to omit - but NOT both.
If you choose to make that modification then you can simply pass in a single List<string>
If you choose to keep your current design then you will need a class with two properties:
public class SelectedColumns {
public List<string> displayed { get; set; }
public List<string> omitted { get; set; }
}

Using 2 maps on the same source?

I have 2 maps that I want to throw into the same source. But it seems one source overrides the second source even though I am targeting different fields.
public class FormViewModel
{
public List<SelectListItem> Items { get; set; }
public string SelectedItem { get; set; }
public string SomeField {get; set;}
// I have many more
}
List<Items> items = Service.GetItems();
FormViewModel viewModel = new FormViewModel()
{
Items = Mapper.Map<List<Items>, List<SelectListItem>>(courses);
};
var fields = Service.GetFields();
viewModel = Mapper.Map<Fields, FormViewModel>(fields);
So now when I do the second map. It will wipe out my first map. How can I stop this?
Edit
I guess I can see why it is happening. I thought it was just filling in those the fields but now I am looking at it and seeing that it is return a new FormViewModel.
I guess I can rearrange my code so that I first do the last map first then add my other map after.
List<CalendarAppointmentReminderVM> vm = Mapper.Map<List<CalendarAppointment>, List<CalendarAppointmentReminderVM>>(taskReminders.Select(x => x.CalendarAppointment).ToList());
Mapper.Map<List<AppointmentReminder>, List<CalendarAppointmentReminderVM>>(taskReminders, vm);
Separately they work. But together the first result gets wiped out by the first one.

pass the output of the first mapping into the second mapping so it doesn't create a new one...
viewModel = Mapper.Map<Fields, FormViewModel>(fields, viewModel);