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Checking duplication using LINQ in collection

I have function which inserts record in database. I want to make sure that there are no duplicate entries in database. Function first checks if there is query string parameter. If there is, then it acts like edit mode otherwise insert mode. There is a function which can return currently added records in database. I need to check duplication based on two columns before insertion in database.
myService = new myService();
myFlow mf = new myFlow();
if (!string.IsNullOrEmpty(Request["myflowid"]))
{
mf = myService.Getmyflow(Convert.ToInt32(Request["myflowid"]));
}
int workcount = 0;
int.TryParse(txtWorkCount.Text, out workcount);
mf.Name = txtName.Text.Trim();
mf.Description = txtDescription.Text.Trim();
mf.FunctionCode = txtFunctioneCode.Text.Trim();
mf.FunctionType = txtFunctioneType.Text.Trim();
mf.WorkCount = workcount;
if (mf.WorkFlowId == 0)
{
mf.SortOrder = 0;
mf.Active = true;
mf.RecordDateTime = DateTime.Now;
message = "Saved Successfully";
}
else
{
_editMode = true;
message = "Update Successfully";
}
}
int myflowId = mfService.AddEditmyflow(mf);
I want to check duplication based on functiontype and functioncode. Another function mfService.Getmyflows() can return currently added records in database.
How can I check duplication using Linq?

First of all, what database do you use? Many databases support upsert behavior (update or insert depending of was data found or not). For example, MERGE in ms sql, MERGE in oracle, INSERT .. ON DUPLICATE in mysql and so on. This could be preferred solution. Upsert is usually an atomic operation.
In your particular case do you you transactions? Are you sure no one will insert data after you ensured about duplicates but before you have inserted your record? Example:
#1 thread #2 thread
look for duplicates
... look for duplicate
no duplicates found ...
no duplicates found
insert data_1
insert data_1
This will end up with duplicates you trying to avoid.
According to your code you populating data from GUI and adding only one item.
If you have access to myService code you could add method to query item by your two columns, instead of querying all items via mfService.Getmyflows() and looking through this collection inside your code. It would be more performant (especially if you have indexes in that columns) and more memory efficient.
And finally, existing of a single element inside collection can be easily done:
var alreadyExist = mfService.Getmyflows()
.Any(x => x.Column1 == value1 && x.Column2 == value2);

How to Modify List of Records in entityFramework

Using Entity Framework,I need to Retreive A List Of Entities Then Manipulate This List Based On Some Conitions, then Save The Final List to Context.
Like This:
Sample
{
int id;
int value;
}
var sampleList=db.samples.toList();
//Add some records to sampleList
sampleList.Add(new sample(){value = 10});
//Change the Value of Some Records in sampleList
sampleList[0].value= 5 ;
db.savechanges()
Added Records to List Are not Tracked And Inserted To DB ,But Changed Values Are Updated.
Strange Behavior Of EF!! Any Explanation???
Thanks!

Hmm, base on your script, what should've been done is something like this.
//var sampleList=db.samples.toList();
//Add some records to sampleList
Sample sampInsertObject = new sample() { value = 10 };
db.samples.Add(sampInsertObject);
db.SaveChanges(); // execute save so that context will execute "INSERT"
/*
EF also executes SCOPE_IDENTITY() after insert to retrieve the
PrimaryKey value from the database to sampInsertObject.
*/
// Change the Value of Some Records in sampleList
var sampUpdateList = db.samples.ToList();
if(sampUpdateList.Count != 0)
{
// Get specific object from sample list
Sample sampUpdateObject = sampUpdateList.ToList()[0];
sampUpdateObject.Value = 5;
db.SaveChanges(); // execute save so that context will execute "UPDATE"
}

Let me first answer the easier question of why your new records were not saved. You cannot just modify the objects and call save changes, you need to either Add or Update the DataBase.
db.Add(sample); // If sample does not exist
db.Update(sample); //If sample already exists and you are updating it
db.SaveChanges();
As for modifying the list and saving that to context. I believe you will have to iterate over the list itself and Add, Delete, Update each Sample Object in it.

Linq to Sql General Help - Insert Statement

I am currently trying to create a new order (which will be shown below) in a web service, and then send that data to insert a new row into the database. For some reason my DBML / Data Context does not allow me to use InsertOnSubmit.
Any ideas? I haven't used Linq to Sql in about 7 months.
Thanks in advance.
[WebMethod]
public string InsertOrderToDatabases()
{
//Start Data Contexts ------
DataContext db = new DataContext(System.Configuration.ConfigurationManager.AppSettings["RainbowCMSConnectionString"]);
DataContext dcSqlOES = new DataContext(System.Configuration.ConfigurationManager.AppSettings["OESConnectionString"]);
//Get table from local database
Table<Schedule> Schedule = db.GetTable<Schedule>();
//Find last order number in databases
var lastOrderNumber = from lOrder in Schedule
orderby lOrder.templ_idn descending
select lOrder.templ_idn;
int firstOrderID;
var firstOrder = lastOrderNumber.FirstOrDefault();
firstOrderID = firstOrder.Value + 1;
qrOrder qrOrd = new qrOrder
{
.... data in here creating a new order
};
//TODO: fix below with an insert on submit
if (qrOrd != null)
{
// **Schedule.InsertOnSubmit(qrOrd);**
}
//db.GetTable<Schedule>().InsertOnSubmit(qrOrd);
try
{
//Submit the changes to the database
db.SubmitChanges();
return "Orders were sent to the databases.";
}
catch ()
{
}
}

Based on your response, it appears that you are using the wrong table, or perhaps the wrong data type. I also noticed that when you declare your localSchedule variable, you declare it as type Table<Schedule>, which means it should contain Schedule entities, not qrOrder entities.
Table<TEntity>.InsertOnSubmit expects a specific strongly typed entity to be passed in. In your case, it is expecting Web_Service.Schedul‌e, but you are trying to pass in a qrOrder.

Schedule.InsertOnSubmit(qrOrd);
That line will not treat to submit changes to connected entity , Try this
db.Schedule.InsertOnSubmit(qrOrd);
db.SubmitChanges();

you can try with
db.GetTable(typeof(Schedule)).InsertOnSubmit(qrOrd);
Or
db.GetTable(qrOrd.GetType()).InsertOnSubmit(qrOrd);

Editing an object in a list<objects> without creating a new instance of that object?

I'm making a database in EF4.1 Code First. I have a table, MedicalPlan, with a one-to-many relationship to a CoverageLevel. CoverageLevel primary key is incrementing. When I create the MedicalPlan I declare the coveragelevels and it creates those tables, like so:
medicalPlan.CoverageLevels = new List<CoverageLevel>();
medicalPlan.CoverageLevels.Add(new CoverageLevel() { Cost = 1200, Description = "single" });
medicalPlan.CoverageLevels.Add(new CoverageLevel() { Cost = 1500, Description = "spouse" });
medicalPlan.CoverageLevels.Add(new CoverageLevel() { Cost = 1100, Description = "family" });
I also have an update function in which I would update a medical plan. I would also like the functionality to update the MedicalPlan's CoverageLevels. In pseudocode, something like:
in medicalPlan edit first item in CoverageLevels() { Cost = 1500 };
The kicker is that I don't actually want to replace the CoverageLevel, as it has a unique auto-incrementing primary key, so if I create a new one it will have a different primary key than the original. Is there a way to do this in the way that I am attempting?

You can mutate entities or related entities in an EF context, and saving changes should properly handle all the updates for you without needing to create new entries:
// get EF Context
var firstCoverage = myMedicalPlan.CoverageLevels.FirstOrDefault();
if (firstCoverage != null) firstCoverage.Cost = 1500;
// save changes

Once you have loaded a MedicalPlan from the database you should be able to work with it and any related entities using Linq or accessing directly via the property on MedicalPlan as if it were a normal collection of .NET objects.
Calling Save would persist back to the database.
E.g.
var medicalPlan = GetMedicalPlanFromDataContext(); //example method
medicalPlan.CoverageLevels.First().Cost = 1500;
//OR
medicalPlan.CoverageLevels[0].Cost = 1500
medicalPlan.Save();
Or probably more likely..
var medicalPlan = GetMedicalPlanFromDataContext();
var coverage = medicalPlan.CoverageLevels.Where(x=>x.Description == "family").Single();
coverage.Cost = 1500;
medicalPlan.Save();

LINQ to SQL Insert Multiple Tables Question

I have 3 tables. A primary EmploymentPlan table with PK GUID EmploymentPlanID and 2 FK's GUID PrevocServicesID & GUID JobDevelopmentServicesID. There are of course other fields, almost exclusively varchar(). Then the 2 secondary tables with the corresponding PK to the primary's FK's.
I am trying to write the LINQ INSERT Method and am struggling with the creation of the keys. Say I have a method like below. Is that correct? Will that even work? Should I have seperate methods for each?
Also, when inserting I didn't think I needed to provide the PK for a table. It is auto-generated, no?
Thanks.
public static void InsertEmploymentPlan(int planID, Guid employmentQuestionnaireID, string user, bool communityJob, bool jobDevelopmentServices, bool prevocServices, bool transitionedPrevocIntegrated, bool empServiceMatchPref)
{
using (var context = MatrixDataContext.Create())
{
var empPrevocID = Guid.NewGuid();
var prevocPlan = new tblEmploymentPrevocService
{
EmploymentPrevocID = empPrevocID
};
context.tblEmploymentPrevocServices.InsertOnSubmit(prevocPlan);
var empJobDevID = Guid.NewGuid();
var jobDevPlan = new tblEmploymentJobDevelopmetService()
{
JobDevelopmentServicesID = empJobDevID
};
context.tblEmploymentJobDevelopmetServices.InsertOnSubmit(jobDevPlan);
var empPlan = new tblEmploymentQuestionnaire
{
CommunityJob = communityJob,
EmploymentQuestionnaireID = Guid.NewGuid(),
InsertDate = DateTime.Now,
InsertUser = user,
JobDevelopmentServices = jobDevelopmentServices,
JobDevelopmentServicesID =empJobDevID,
PrevocServices = prevocServices,
PrevocServicesID =empPrevocID,
TransitionedPrevocToIntegrated =transitionedPrevocIntegrated,
EmploymentServiceMatchPref = empServiceMatchPref
};
context.tblEmploymentQuestionnaires.InsertOnSubmit(empPlan);
context.SubmitChanges();
}
}
I understand I can use more then 1 InsertOnSubmit(), See this question, I just don't understand how that would apply to my situation and the PK/FK creation.

The pk can be auto generated when the table's definition in the db does it for you. Also the property for the corresponding pk on the linq model has to configured to be updated after the insert, so it gets the auto generated ID.
I don't think the relation on those tables is on your linq model. Otherwise you should be able to do:
using (var context = MatrixDataContext.Create())
{
var empPlan = new tblEmploymentQuestionnaire
{
CommunityJob = communityJob,
InsertDate = DateTime.Now,
InsertUser = user,
JobDevelopmentServices = jobDevelopmentServices,
JobDevelopmentService = new tblEmploymentJobDevelopmetService(),
PrevocServices = prevocServices,
PrevocService = new tblEmploymentPrevocService(),
PrevocServicesID =empPrevocID,
TransitionedPrevocToIntegrated =transitionedPrevocIntegrated,
EmploymentServiceMatchPref = empServiceMatchPref
};
context.tblEmploymentQuestionnaires.InsertOnSubmit(empPlan);
context.SubmitChanges();
}
ps. not having the relation in the model is a design decision, so the above doesn't mean that's the only way to do it. The way you showed (with the extra SubmitChanges calls as in the other answer) is perfectly valid, just responds to a different design.

I think the issue is (if I understand it correctly) you are deferring the inserting, except you don't know it...
Since you're creating FKs but differing their insertion until the end, it doesn't know what to do, so when you try to create the main entry it's enforcing the FK constraints (which might not exist yet), thus failing. Try creating the FK entries and actually submitting the changes to the database before insert the main entry.
For example, say you have the following tables:
Child
Toy
ToyOwner
ToyOwner has FK constraints on Child and Toy. If the entries are missing in that table, you will not be able to insert an entry into ToyOwner. So you'd have to do something like the following:
Child myChild;
Toy myToy;
//Queue up the changes that are going to be submitted
InsertOnSubmit(myChild)
InsertOnSubmit(myToy)
//Submit the queue
SubmitChanges();
//Now that those FKs are filled, we can insert the main entry with those FK values
ToyOwner = new myToyOwner
myToyOwner.Child = myChild
myToyOwner.Toy = myToy
//And insert the new queue into the DB
InsertOnSubmit(myToyOwner)
SubmitChanges();