Develop Reference

I try to make a lamda expression in C# for filtering a list and can't make it work when I compare a variable to an item in an array

So I have the gui set up so that I have two main listboxes. I'm still figuring out what kind of gui I want for this application so there is another one but that's not relevant. One listbox is a list of options for what you want to check for a department or an employee. The other is a list of departments. Right now I have the functionality for the name option to view the names of employees for a department. I just need to know how I can filter a list so that the only employees that show up are the ones who are in the chosen department after I click on the submit button. I figured I would use a lambda expression for that and it hasn't been working for me. I really want to know how to use lambda expressions better so please only give me a solution that involves using them. If it's impossible or if it would be more efficient to do something else then let me know.
File where I put reads and set dept array to file contents
//list of employees
public static List<Employee> EmployeeList = new List<Employee>();
//array to hold the options users have for interacting with info
public static string[] OptionsArr;
//array to hold the departments
public static string[] DeptsArr;
//skipping around same file to relevant code
//set the departments array to the contents of the depts file
DeptsArr = File.ReadAllLines("..\\..\\departments.txt");
Not sure if needed
Method for populating DeptListBox
private void UpdateDeptListBox()
{
//set up for new info
DeptListBox.Items.Clear();
//prevent interfence with update
DeptListBox.BeginUpdate();
//set department listbox to depts array
DeptListBox.DataSource = Program.DeptsArr;
DeptListBox.EndUpdate();
}
Problem Method - the submit button method
List<Employee> ResultList = new List<Employee>();
//name
if (OptionsListBox.SelectedIndex == 1)
{
//user selects Marketing department
if (DeptListBox.SelectedIndex == 0)
{
//problem is either with lambda exp or Program.DeptsArr comparison
foreach (Employee empl in Program.EmployeeList.Where(empl => empl.Dept.CompareTo(Program.DeptsArr[0]) == 0).ToList())
{
//this doesn't happen
ResultList.Add(empl);
}
for (int i = 0; i<ResultList.Count; i++)
{
ResultListBox.Items.Add(ResultList[i].Lname + " " + ResultList[i].Fname + " " + ResultList[i].Dept);
}
}
}
}

For me it can be helpful when I am having issues to break stuff down and look at smaller pieces. Are you sure the issue is your lambda function? It may be your options listbox != 1 or that the data is not being read in correctly.
As far as I can tell, this part should work. Although there are some issues with it:
foreach (Employee empl in Program.EmployeeList.Where(empl =>empl.Dept.CompareTo(Program.DeptsArr[0]) == 0).ToList())
{
//this doesn't happen
ResultList.Add(empl);
}
You could start with just the Employee lambda function and hard code the values. Maybe something like this which does indeed produce the correct results (Bob and Brandon)
List<Employee> ResultList = new List<Employee>();
List<Employee> EmployeeList = new List<Employee> {
new Employee{ Name = "Bob", Dept = "Accounting" },
new Employee{ Name = "Larry", Dept = "A" },
new Employee{ Name = "Margret", Dept = "B" },
new Employee{ Name = "Brandon", Dept = "Accounting" }
};
string[] DeptsArr = new string[2];
DeptsArr[0] = "Accounting";
DeptsArr[1] = "A";
//user selects Marketing department
if (departmentIndex == 0)
{
foreach (Employee empl in EmployeeList.Where(empl => empl.Dept.CompareTo(DeptsArr[0]) == 0).ToList())
{
ResultList.Add(empl);
}
}
However your lamda function inside a foreach loop is redundant. You can think of a lambda function as an instruction for running a foreach loop. A foreach loop by itself could look like this:
List<Employee> ResultList = new List<Employee>();
foreach (Employee empl in EmployeeList)
{
if(empl.Dept == DeptsArr[0])
{
ResultList.Add(empl);
}
}
You could get the same result as the foreach loop above, by using the following lamda function:
List<Employee> ResultList = EmployeeList.Where(empl => empl.Dept == DeptsArr[0]).ToList();
A final note is that the "ToList()" on the end of that lambda function is what executes the loop and returns the result as a List. Many times this is not required. Without the "ToList()" part an IEnumerable will be returned which you may be able to use instead. Using an IEnumerable instead of calling ToList() can have better performance in many scenarios.

If you want to test whether a specific value is in an array then you call Contains on that array, e.g.
var allEmployees = new List<Employee>();
// Populate allEmployees here.
var selectedEmployees = allEmployees.Where(e => selectedDepartments.Contains(e.Department)).ToArray();
The selectedEmployees array will contain only the Employee objects from the allEmployees list with a Department property value that is contained in the selectedDepartments array/collection.

NetSuite - Search customers by complex query

I am trying to search customers who contain these fields : email or firstName or lastName or id.
must be an OR condition between of them.
for example
var freeText = "shomeone#gmai";
var customers = SearchForCustomersWhoContainsThisData(freeText)
how can i build this query in c#?
public List<Customer> SearchForCustomersWhoContainsThisData(string search_text)
{
CustomerSearch custSearch = new CustomerSearch();
SearchStringField searchField = new SearchStringField();
searchField.#operator = SearchStringFieldOperator.contains;
searchField.operatorSpecified = true;
searchField.searchValue = search_text;
CustomerSearchBasic custBasic1 = new CustomerSearchBasic();
custBasic1.firstName = searchField;
CustomerSearchBasic custBasic2 = new CustomerSearchBasic();
custBasic2.lastName = searchField;
custSearch.basic = custBasic1;
//custSearch.basic = custBasic2; how to add this with or between
// Search for the customer entity who contains this text
SearchResult response = _crmNetSuitService.search(custSearch);
var searchResults = response.recordList.Select(t => (Customer)t).ToList();
return searchResults;
}
I expect to find customers who one of these fields contains this search-text:
email, fName, lName, Id.

As per NetSuite SuiteAnswers id 31408
Web Services > Search > How to set a field filter for one value OR another value
Currently, expressions are not supported via Web Services searches.
In order to Search where a field is one value or another. It is necessary to submit two search requests, then merge the results in the application code.

Iterating over two lists in c#

So i have a function that gets a list of students from a web service and also query the localdb for all the students in there. the data is placed in two different list. So i want to check to see if a new student already exists in the localdb List. if it does, update it and it if doesn't then add it. i unable to get it working . I am trying to perform this using LINQ, but i can't seem to get it working right. My LINQ skills are amateurish at best.
public async Task GetStudents()
{
String controllerName = "Students";
List<Students> newStudentData = await RunGetAsync<Students>(controllerName);
// get all the service types that already exists in the localStudent Db
List<Students> currentStudentData = db.Studentss.ToList();
foreach (Students existingStudents in currentStudentData)
{
foreach (Students newStudents in newStudentData)
{
IEnumerable<Students> selectStudents = from student in newStudentData // check if Students exist in the database
where student.Id == existingStudents.Id
select student;
if (selectStudents == null) // didn't find it, then add it
{
db.Students.Add(newStudents);
}
if (selectStudents != null) // found it , then update the informations
{
Students updatedStudents = new Students();
foreach (var field in selectStudents)
{
updatedStudents.FName = field.FName;
updatedStudents.LName = field.LName;
updatedStudents.ZipCode = field.ZipCode;
updatedStudents.AccessCode = field.AccessCode;
}
db.Entry(updatedStudents).State = System.Data.Entity.EntityState.Modified;
}
}
}
db.SaveChanges();
}
Thank you very much for your help.

you're looping more than you need :
foreach (Students newStudents in newStudentData)
{
var student = currentStudentData.FirstOrDefault(s => s.Id == newStudents.Id);
if(student == null)
{
//add
}
else
{
//update
}
}
with FirstOrDefault you can find out if it exists and get a reference to it at the same time, if it does.

You could use Intersect and Except like below:
//Find students that already exist to update
var updateStudents = currentStudentData.Intersect(newStudentData);
//Find new students to add
var addStudents = newStudentData.Except(currentStudentData);

Entity Framework - Insert multiple complex objects at once

I am writing a parser for one of website, which have products connected to categories. I am trying to build my own database with these items.
I have decided to use Entity Framework, but I am new to this framework, so here's my problem:
During parsing i have multiple items with same category. But categories are kind of trees. I mean, category have a reference to parentCategory.
During of parsing i have a list of category inheritance f.e : category1 -> category1.1 -> category1.1.1
Each product I parse and add to database need to verify if that category exist and go through category inheritance to create non existing categories.
Code looks like this:
Category parentCategory = null;
foreach (var sCategory in categories)
{
var currentCategory = d.CategorySet.SingleOrDefault(category => category.Name == sCategory && category.Parent == parentCategory);
if (currentCategory == null)
{
currentCategory = new Category(){Name = sCategory,Parent = parentCategory};
if(parentCategory != null)
d.Entry(parentCategory).State = EntityState.Unchanged;
}
parentCategory = currentCategory;
}
But in this case, SingleOrDefault LinQ does not work because of exception:
Unable to create a constant value of type 'DataBaseModel.Category'. Only primitive types or enumeration types are supported in this context.
I know that I should compare IDs of category, but in this case it needs to saveChanges into db every time I add sth to DB.
Is there any other possibility to handle that?

I have solved this issue by creating local Dictionaries of Categories and before usage, fill this dictionaries by data from database.
_categoriesDictionary.Clear();
foreach (var category in this.Container.CategorySet)
{
Category temp = category;
string fullCategoryString = "";
while (temp != null)
{
fullCategoryString = fullCategoryString.Insert(0, temp.Name + ";");
temp = temp.Parent;
}
_categoriesDictionary.Add(fullCategoryString, category);
}
And then when analyzing the record:
Category parentCategory = null;
string fullCatString = "";
foreach (var sCategory in categories)
{
fullCatString += sCategory + ";";
Category currentCategory;
if (!_categoriesDictionary.TryGetValue(fullCatString, out currentCategory))
{
currentCategory = new Category()
{
Name = sCategory,
Parent = parentCategory
};
this.Container.CategorySet.Add(currentCategory);
_categoriesDictionary.Add(fullCatString, currentCategory);
}
parentCategory = currentCategory;
}
result.Category = parentCategory;
This has another adventage from my point of view:
Its collecting data on start, and then do not query DB every time

Cannot implicitly convert type '.List<AnonymousType#1>' to '.List<WebApplication2.Customer>'

In the following code that returns a list:
public List<Customer> GeAllCust()
{
var results = db.Customers
.Select(x => new { x.CustName, x.CustEmail, x.CustAddress, x.CustContactNo })
.ToList()
return results;
}
I get an error reporting that C# can't convert the list:
Error: Cannot implicitly convert type System.Collections.Generic.List<AnonymousType#1> to System.Collections.Generic.List<WebApplication2.Customer>
Why is that?
Here's a screenshot showing some additional information that Visual Studio provides in a tooltip for the error:
Is it right way to return some columns instead of whole table....?
public object GeAllCust()
{
var results = db.Customers.Select(x => new { x.CustName, x.CustEmail, x.CustAddress, x.CustContactNo }).ToList();
return results;
}

When you look the code:
x => new { ... }
This creates a new anonymous type. If you don't need to pull back only a particular set of columns, you can just do the following:
return db.Customers.ToList();
This assumes that Customers is an IEnumerable<Customer>, which should match up with what you are trying to return.
Edit
You have noted that you only want to return a certain subset of columns. If you want any sort of compiler help when coding this, you need to make a custom class to hold the values:
public class CustomerMinInfo
{
public string Name { get; set; }
public string Email { get; set; }
public string Address { get; set; }
public int? ContactNumber { get; set; }
}
Then change your function to the following:
public List<CustomerMinInfo> GetAllCust()
{
var results = db.Customers.Select(x => new CustomerMinInfo()
{
Name = x.CustName,
Email = x.Email,
Address = x.Address,
ContactNumber = x.CustContactNo
})
.ToList();
return results;
}
This will work, however, you will lose all relationship to the database context. This means if you update the returned values, it will not stick it back into the database.
Also, just to repeat my comment, returning more columns (with the exception of byte arrays) does not necessarily mean longer execution time. Returning a lot of rows means more execution time. Your function is returning every single customer in the database, which when your system grows, will start to hang your program, even with the reduced amount of columns.

You are selecting to an anonymous type, which is not a Customer.
If you want to do (sort of) this, you can write it like this:
return db.Customers.Select(x => new Customer { Name = x.CustName, Email = x.CustEmail, Address = x.CustAddress, ContactNo = x.ContactNo }).ToList();
This assumes the properties on your Customer object are what I called them.
** EDIT ** Per your comment,
If you want to return a subset of the table, you can do one of two things:
Return the translated form of Customer as I specified above, or:
Create a new class for your business layer that only has only those four fields, and change your method to return a List<ShrunkenCustomer> (assuming ShunkenCustomer is the name that you choose for your new class.)

GetAllCust() is supposed to return a List of Customer, Select New will create a list of Anonymous Types, you need to return a list of Customer from your query.
try:
var results = db.Customers.Select( new Customer{CustName = x.CustName}).ToList(); //include other fields

I guess Customer is a class you have defined yourself?
The my suggestion would be to do something like the following:
var results = db.Customers.Select(x => new Customer(x.Custname, x.CustEmail, x.CustAddress, x.CustContactNo)).ToList();
The reason is that you are trying to return a list of Customer but the results from your link is an anonymous class containing those four values.
This would of course require that you have a constructor that takes those four values.

Basically whatever u got in var type, loop on that and store it in list<> object then loop and achieve ur target.Here I m posting code for Master details.
List obj = new List();
var orderlist = (from a in db.Order_Master
join b in db.UserAccounts on a.User_Id equals b.Id into abc
from b in abc.DefaultIfEmpty()
select new
{
Order_Id = a.Order_Id,
User_Name = b.FirstName,
Order_Date = a.Order_Date,
Tot_Qty = a.Tot_Qty,
Tot_Price = a.Tot_Price,
Order_Status = a.Order_Status,
Payment_Mode = a.Payment_Mode,
Address_Id = a.Address_Id
});
List<MasterOrder> ob = new List<MasterOrder>();
foreach (var item in orderlist)
{
MasterOrder clr = new MasterOrder();
clr.Order_Id = item.Order_Id;
clr.User_Name = item.User_Name;
clr.Order_Date = item.Order_Date;
clr.Tot_Qty = item.Tot_Qty;
clr.Tot_Price = item.Tot_Price;
clr.Order_Status = item.Order_Status;
clr.Payment_Mode = item.Payment_Mode;
clr.Address_Id = item.Address_Id;
ob.Add(clr);
}
using(ecom_storeEntities en=new ecom_storeEntities())
{
var Masterlist = en.Order_Master.OrderByDescending(a => a.Order_Id).ToList();
foreach (var i in ob)
{
var Child = en.Order_Child.Where(a => a.Order_Id==i.Order_Id).ToList();
obj.Add(new OrderMasterChild
{
Master = i,
Childs = Child
});
}
}