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LINQ query continues to return null after 1st successful call

I have an upload function in my ASP.NET MVC web application which allows a user to upload a document. The system then uses various OCR APIs to read data from the uploaded document, this data is then saved in the "SecondarySchoolSurvey" table in the database. I have a LINQ query in the upload code which finds a row in the database "SecondarySchoolSurvey" table that matches the Id passed in. Various fields in this row are then updated and saved back into the database.
Now this upload function works fine first time. Although if I try to use the upload function again (without restarting the IIS server) then it throws the following error Object reference not set to an instance of an object.
After setting various break points I noticed that the LINQ query: var s1 = db.SecondarySchoolSurveys.FirstOrDefault(s => s.Id == id); returns null the 2nd time it is called i.e. it does not find the record which matches the Id passed in, even though it exists in the database.
So for now, I need to reset the web app IIS server after every time I want to test the upload function. Otherwise this LINQ query with return null the 2nd time I try upload a document. Has anybody seen anything like this before? I'm not sure how useful it will be providing code but here is one of the class, the one which contains the LINQ query:
public class SurveyCheckboxAnswers
{
private RDSContext db = new RDSContext();
//Adds Question 2 answer
public void AddQ2Answer(SurveyCheckboxCollections checkboxes, int id)
{
//find Survey record in db which matches id in order to update with checkbox data
var s1 = db.SecondarySchoolSurveys.FirstOrDefault(s => s.Id == id);
CheckboxData q2Male = checkboxes.SecondarySchoolCheckboxes["Q2Male"];
CheckboxData q2Female = checkboxes.SecondarySchoolCheckboxes["Q2Female"];
CheckboxData q2Other = checkboxes.SecondarySchoolCheckboxes["Q2Other"];
CheckboxData q2DontWantToSay = checkboxes.SecondarySchoolCheckboxes["Q2DontWantToSay"];
//numbers of checkboxes marked for validation
int checkboxValidaiton = 0;
//update SecondarySchoolSurvey checkbox answers in database with IsChecked values from checkbox dictionary
if (q2Male.IsChecked)
{
s1.Q2 = Gender.Male;
checkboxValidaiton++;
}
if (q2Female.IsChecked)
{
s1.Q2 = Gender.Female;
checkboxValidaiton++;
}
if (q2Other.IsChecked)
{
s1.Q2 = Gender.Other;
checkboxValidaiton++;
}
if (q2DontWantToSay.IsChecked)
{
s1.Q2 = Gender.None;
checkboxValidaiton++;
}
//validate only 1 checkbox has been marked
if(checkboxValidaiton == 0)
{
s1.Flag = true;
s1.FlagContent += "| Question2: no checkboxes marked. ";
}
else if (checkboxValidaiton > 1)
{
s1.Flag = true;
s1.FlagContent += "| Question2: more than 1 checkboxes marked. ";
}
db.SaveChanges();
}
//Adds Question 6 answer
public void AddQ6Answer(SurveyCheckboxCollections checkboxes, int id)
{
//find Survey record in db which matches id in order to update with checkbox data
var s1 = db.SecondarySchoolSurveys.FirstOrDefault(s => s.Id == id);
CheckboxData q6Higher = checkboxes.SecondarySchoolCheckboxes["Q6Higher"];
CheckboxData q6Ordinary = checkboxes.SecondarySchoolCheckboxes["Q6Ordinary"];
CheckboxData q6Other = checkboxes.SecondarySchoolCheckboxes["Q6Other"];
//numbers of checkboxes marked for validation
int checkboxValidaiton = 0;
if (q6Higher.IsChecked)
{
s1.Q6a = MathLevel.Higher;
checkboxValidaiton++;
}
if (q6Ordinary.IsChecked)
{
s1.Q6a = MathLevel.Ordinary;
checkboxValidaiton++;
}
if (q6Other.IsChecked)
{
s1.Q6a = MathLevel.Other;
checkboxValidaiton++;
}
//validate only 1 checkbox has been marked
if (checkboxValidaiton == 0)
{
s1.Flag = true;
s1.FlagContent += "| Question6: no checkboxes marked. ";
}
else if (checkboxValidaiton > 1)
{
s1.Flag = true;
s1.FlagContent += "| Question6: more than 1 checkboxes marked. ";
}
db.SaveChanges();
}
//Adds Question 7 answer
public void AddQ7Answer(SurveyCheckboxCollections checkboxes, int id)
{
//find Survey record in db which matches id in order to update with checkbox data
var s1 = db.SecondarySchoolSurveys.FirstOrDefault(s => s.Id == id);
CheckboxData q7Physics = checkboxes.SecondarySchoolCheckboxes["Q7Physics"];
CheckboxData q7Biology = checkboxes.SecondarySchoolCheckboxes["Q7Biology"];
CheckboxData q7Chemistry = checkboxes.SecondarySchoolCheckboxes["Q7Chemistry"];
CheckboxData q7Science = checkboxes.SecondarySchoolCheckboxes["Q7Science"];
CheckboxData q7None = checkboxes.SecondarySchoolCheckboxes["Q7None"];
//numbers of checkboxes marked for validation
int checkboxValidaiton = 0;
if (q7Physics.IsChecked)
{
s1.Q7 = "Physics";
checkboxValidaiton++;
}
if (q7Biology.IsChecked)
{
s1.Q7 += "Biology";
checkboxValidaiton++;
}
if (q7Chemistry.IsChecked)
{
s1.Q7 += "Chemistry";
checkboxValidaiton++;
}
if (q7Science.IsChecked)
{
s1.Q7 += "Science Junior";
checkboxValidaiton++;
}
if (q7None.IsChecked)
{
s1.Q7 += "None";
checkboxValidaiton++;
}
//validate only 1 checkbox has been marked
if (checkboxValidaiton == 0)
{
s1.Flag = true;
s1.FlagContent += "| Question7: no checkboxes marked. ";
}
db.SaveChanges();
}
...
...
...
}

Your problem here most likely lies in the fact you are using a private variable for the db context. The appropriate way to open/close the connection to your db using a context is to use a using statement like so:
using(var db = new RDSContext())
{
//...Do work here with your context
}
Per MSDN
The lifetime of the context begins when the instance is created and ends when the instance is either disposed or garbage-collected. Use using if you want all the resources that the context controls to be disposed at the end of the block. When you use using, the compiler automatically creates a try/finally block and calls dispose in the finally block.

Since your query is running but is returning null, your db context is likely valid. That means the issue is likely the query itself. I suspect that on subsequent runs, you are passing in a different id that has no record in your database. Asking the db for the first record, if any, that matches the supplied id therefor returns null. Use a breakpoint to inspect both the provided id and the generated sql. Check in your db that you have a row for the id.
On another note, I would suggest that you use the method First or Single instead of FisrtOrDefualt if you expect the query to always return a row. This will throw an error if there are no matching rows, which guarantees that you have a not-null result returned if no error is thrown. The advantage is that after the method you now know that there was a matching row, whereas otherwise you may have to include a null check.
There is a great table on these operators here

How to change items in cache

Hello i want to change and alter values inside the cache of my acumatica cache i would like to know how to do it
for example i want to change the Ext. Cost value pro grammatically of the first line or the second line or can i check if there is already a "Data Backup" on transaction Descr.
public delegate void PersistDelegate();
[PXOverride]
public void Persist(PersistDelegate baseMethod)
{
if (Globalvar.GlobalBoolean == true)
{
PXCache cache = Base.Transactions.Cache;
APTran red = new APTran();
red.BranchID = Base.Transactions.Current.BranchID;
red.InventoryID = 10045;
var curyl = Convert.ToDecimal(Globalvar.Globalred);
red.CuryLineAmt = curyl * -1;
cache.Insert(red);
}
else
{
}
baseMethod();
}
this code add a new line on persist but if it save again it add the same line agaub u wabt ti check if there is already a inventoryID =10045; in the cache
thank you for your help

You can access your cache instance by using a view name or cache type. Ex: (Where 'Base' is the graph instance)
Base.Transactions.Cache
or
Base.Caches<APTran>().Cache
Using the cache instance you can loop the cached values using Cached, Inserted, Updated, or Deleted depending on which type of record you are looking for. You can also use GetStatus() on an object to find out if its inserted, updated, etc. Alternatively calling PXSelect will find the results in cache (PXSelectReadOnly will not).
So you could loop your results like so:
foreach (MyDac row in Base.Caches<MyDac>().Cache.Cached)
{
// logic
}
If you know the key values of the cache object you are looking for you can use Locate to find by key fields:
var row = (MyDac)Base.Transactions.Cache.Locate(new MyDac
{
MyKey1 = "",
MyKey2 = ""
// etc... must include each key field
});
As Mentioned before you can also just use a PXSelect statement to get the values.
Once you have the row to update the values you set the object properties and then call your cache Update(row) before the base persist and you are good to go. Similar if needing to Insert(row) or Delete(row).
So in your case you might end up with something like this in your persist:
foreach (APTran row in Base.Transactions.Cache.Cached)
{
if (Globalvar.GlobalBoolean != true || row.TranDesc == null || !row.TranDesc.Contains("Data Backup"))
{
continue;
}
//Found my row
var curyl = Convert.ToDecimal(Globalvar.Globalred);
row.CuryLineAmt = curyl * -1;
Base.Transactions.Update(row);
}

C# Comparing data with database by using array

My database contains 2 records. So, I retrieve these 2 records and store in array. Let's say my database have start point, destination, terminal and departure time. If user trying to add same start point, same destination, same terminal and same departure time, it will show error message. But if user trying to add same start point, same destination, same terminal but DIFFERENT departure time. It suppose to allow user add, but I having problem with user not allow to add.
Example:
These record are in my database
Record 1 : Terminal = 1 , From = US , To = UK, Time = 10.00
Record 2 : Terminal = 1 , From = US , To = AUS , Time = 2.00
When user want to add new record
User wish to add: Terminal = 1, From = US, To = AUS, Time = 10.00
It's tell me record exist because the time 10.00 exist in other record which is in different destination. Anyone can help?
if (ow_terminal.Any(s => ddlterminal.SelectedValue.Contains(s))
&& ow_depart.Any(s => ddlDeparture.SelectedValue.Contains(s))
&& ow_origin.Any(s => ddlOrigin.SelectedValue.Contains(s))
&& ow_destination.Any(s => ddlDestination.SelectedValue.Contains(s)))
{
lblMessage.Text = "Record exist";
}
else
{
lblMessage.Text = "No record exist"
}

The problem is with your Linq statement.
Think logically about what it is actually saying:
if(terminal_array.Any(s => new_terminal_record.Contains(s)))
So if ANY of the values in your terminal_array matches the new terminal record that the user entered then this statement is true, and your code will then evaluate the next line
if(depart_array.Any(s => new_depart_record.Contains(s)))
And it will do the same thing, if ANY of the values in your depart array matches the new departure record that the user entered then this statement is also true.
What you most likely want to do is to store the records in an array of whatever your record type is and do the Linq statement over each record in that array, something along the lines of:
if(records_array.Any(s => new_record.terminal.Equals(s.terminal) &&
new_record.depart.Equals(s.depart) &&
new_record.origin.Equals(s.origin) &&
new_record.destination.Equals(s.destination)))
{
// Record Exists
}
else
{
// No Record Exists
}
For a more complete example, I have replicated your implementation and then included my implementation:
class Program
{
// Example of database records
struct _dbTypes
{
public string terminal;
public string depart;
public string origin;
public string destination;
};
static void Main(string[] args)
{
// First record
_dbTypes record1;
record1.terminal = "1";
record1.depart = "10.00";
record1.origin = "US";
record1.destination = "UK";
// Second record
_dbTypes record2;
record2.terminal = "1";
record2.depart = "2.00";
record2.origin = "US";
record2.destination = "AUS";
// Your implementation has each of the records internals
// separated into their own array
List<String> terminals = new List<string>();
List<String> departs = new List<string>();
List<String> origins = new List<string>();
List<String> destination = new List<string>();
terminals.Add(record1.terminal);
terminals.Add(record2.terminal);
departs.Add(record1.depart);
departs.Add(record2.depart);
origins.Add(record1.origin);
origins.Add(record2.origin);
destination.Add(record1.destination);
destination.Add(record2.destination);
// The NEW record that the user has entered
_dbTypes record3;
record3.terminal = "1";
record3.depart = "10.00";
record3.origin = "US";
record3.destination = "AUS";
// Example of your implementation
if (terminals.Any(s => record3.terminal.Contains(s)) &&
departs.Any(s => record3.depart.Contains(s)) &&
origins.Any(s => record3.origin.Contains(s)) &&
destination.Any(s => record3.destination.Contains(s)))
{
// Will fall into here
Console.WriteLine("Record exists");
}
else
{
Console.WriteLine("No record exists");
}
// What you should probably be doing...
//
// Array of your record type
List<_dbTypes> dataBaseEntries = new List<_dbTypes>();
//
// Add the first two records as a whole record, not separated out
dataBaseEntries.Add(record1);
dataBaseEntries.Add(record2);
// Now you want to do the Linq statement over the record
// AND'ing each .Equals on the current records internal objects
if (dataBaseEntries.Any(s => record3.terminal.Equals(s.terminal) &&
record3.depart.Equals(s.depart) &&
record3.origin.Equals(s.origin) &&
record3.destination.Equals(s.destination)))
{
Console.WriteLine("Record exists");
}
else
{
Console.WriteLine("No record exists");
dataBaseEntries.Add(record3);
}
}
}

From what I can tell, you seem to be storing the information for each record in separate arrays, one each for terminal, depart, origin, and destination. This is a bit problematic since there isn't a concrete way of determining that the information belongs to the same record UNLESS for some reason, the information are ordered in the array per record:
example:
ow_terminal[0] = 1
ow_depart[0] = "US"
ow_origin[0] = "UK"
ow_destination[0] = 10.00
If this is the case, then you have to change your if statement logic. I don't think LINQ can help in this case, but you can try:
bool exists = false;
for(int i = 0; i < ow_terminal.Count; i++)
{
if(ddlterminal.SelectedValue.Contains(ow_terminal[i])
&& ddlDeparture.SelectedValue.Contains(ow_depart[i])
&& ddlOrigin.SelectedValue.Contains(ow_origin[i])
&& ddlDestination.SelectedValue.Contains(ow_destination[i]))
{
exists = true;
break;
}
}
if(exists) lblMessage.Text = "Record exist";
else lblMessage.Text = "No record exist";
The code checks the values of each array in the same position for equality. Again, this would only work if the items on all of the arrays are arranged per record. ALSO, you may want to change the equality check since Contains may not be best fit for your purpose ("US" is contained in "RUSSIA", for example.)
HOWEVER, managing four arrays and making sure that they are ordered correctly all the time is very fragile. What you want to do is to create just one array (or list) of objects that correspond to your record with corresponding properties:
public class FlightRecord
{
public int Terminal {get;set;}
public string From {get;set;}
public string To {get;set;}
public decimal Time {get;set;} // How are you storing time?
}
Create an array of FlightRecords from your database records and then you can do your logic like you wanted with a few minor changes:
if (ow_flightrecords.Any(s => ddlterminal.SelectedValue.Contains(s.Terminal.ToString()
&& ddlDeparture.SelectedValue.Contains(s.Time.ToString())
&& ddlOrigin.SelectedValue.Contains(s.From)
&& ddlDestination.SelectedValue.Contains(s.To)))
{
lblMessage.Text = "Record exist";
}
else
{
lblMessage.Text = "No record exist"
}
This one is more robust and you can use LINQ easily. Again, change how you do the comparisons since Contains may not be as good a fit for your purpose as you think it is.
And as Synchro noted, it's probably a good idea to do the check on the database directly via a stored procedure before you do the actual INSERT into the database. It will be much faster this way.

C# foreach statement

I need some help with a for each statement, basically what happens is when a user edits a value within a cell, my foreach will apply this to all cells within the datagrid and change the value of them all, i need my foreach statement to work by iterating through the datagrid but only change the selected row that has been edited
try
{
//loop through each of the rows in the dgv
foreach (DataGridViewRow row in dgvDetials.SelectedRows)
{
int intQtyInsp = 0;
//if quantity inspected is empty:
if (row.Cells[2].Value.ToString() == "")
{
//quantity inspected is 0. Prevents null value errors:
intQtyInsp = 0;
}
intQtyInsp =
Int32.Parse(dgvDetials.CurrentRow.Cells[2].Value.ToString());
if (intQtyInsp < 0) // checks the cell for a negative value
{
intQtyInsp = 0; // if cells is negative submits value as Zero
}
else
{
//sets quantity inspected to value entered
intQtyInsp = Int32.Parse(row.Cells[2].Value.ToString());
}
if (intQtyInsp == 0) //if quantity inspected is 0. Ignore row.
{
}
else //else gather details and insert row as production.
{
area = dtArea2.Rows[0]["area_code"].ToString();
inspDate = dtpInspectionDate.Value.ToString("MM/dd/yyyy");
inspShift = cbShift.Text;
partNo = row.Cells[0].Value.ToString();
// dieCode = row.Cells[0].Value.ToString();
dieCode = "";
machine = "";
qtyInsp = intQtyInsp;
qtyInspRecorded = Int32.Parse(row.Cells[5].Value.ToString());
comment = "";
//machine = row.Cells[3].Value.ToString();
if (qtyInspRecorded == 0)
{
SQLMethods.insertProduction(area,
inspDate,
inspShift,
partNo,
dieCode,
qtyInsp,
comment,
machine);
}
else
{
SQLMethods.updateProduction(area,
inspDate,
inspShift,
partNo,
dieCode,
(qtyInspRecorded + qtyInsp),
comment,
machine);
}
}
}
retrieveData(); //reset values
}
catch (Exception ex)
{
MessageBox.Show(
"Error instering production values. Processed with error: "
+ ex.Message);
}

First of all, I would simplify the code here a little by splitting it into several methods that may be called from the For-loop. That would make it easier to read, and thereby easier to help you too. Just to provide an example, the following:
if (intQtyInsp < 0) // checks the cell for a negative value
{
intQtyInsp = 0; // if cells is negative submits value as Zero
}
else
{
//sets quantity inspected to value entered
intQtyInsp = Int32.Parse(row.Cells[2].Value.ToString());
}
could be replaced with something like:
int intQtyInsp = SetQuantityInspected();
Then that method could contain the if-structure. Repeat this for other parts of the code in the loop too. Trust me, this will make your life easier.
Also, it seems as if the result of this section is never used; the value of intQtyInsp is overwritten right afterwards!:
if (row.Cells[2].Value.ToString() == "")
{
//quantity inspected is 0. Prevents null value errors:
intQtyInsp = 0;
}
As for your question: I'm not sure how you would get the id of the row that is currently being edited. (If possible (?), it might be getter to loop through the table / data source behind the datagrid?).
In any case, what you need to do is something like the following inside your loop:
if(IsCurrentlyEditedRow(row)){
...
// (all the stuff currently in the body of your loop goes here)
...
}
Now you can implement the method IsCurrentlyEditedRow() to return True or False depending on whether or not the id of the current row is the the same as that of the one you are editing.
Sorry if this is not a very specific and detailed answer, hope it is of some use anyway.

C# Updating Data Issue

I am currently using one button for inserting/updating content within a table. It then takes the uploaded CSV and inserts or updates it into a data table depending on whether the row exists or not.
Here is the code fired after the button's OnClick:
if (ExcelDDL.SelectedValue == "Time Points" && fileName == "TimePoints.csv")
{
var GetTPoints = (SEPTA_DS.TimePointsTBLDataTable)tpta.GetDataByCategory(CategoryDDL.SelectedItem.ToString());
//Loop through each row and insert into database
int i = 0;
foreach (DataRow row in TempRouteDataTable.Rows)
{
//Gather column headers
var category = Convert.ToString(CategoryDDL.SelectedItem);
var agency = Convert.ToString(row["Agency"]);
if (agency == null || agency == "")
{
//If row is empty skip it entirely
goto skipped;
}
var route = Convert.ToString(row["Route"]);
var GetRShortName = (SEPTA_DS.RoutesTBLDataTable)rta.GetDataByRouteID(route);
var newRoute = "";
if (GetRShortName.Rows.Count > 0)
{
newRoute = Convert.ToString(GetRShortName.Rows[0]["route_short_name"]);
}
var direction = Convert.ToString(row["Direction"]);
var serviceKey = Convert.ToString(row["Service Key"]);
var language = Convert.ToString(row["Language"]);
var stopID = Convert.ToString(row["Stop ID"]);
var stopName = Convert.ToString(row["Stop Name"]);
if (stopName.Contains("accessible"))
{
string[] noHTML = stopName.Split('>');
int insertH = Convert.ToInt32(hta.InsertHandicapRow(newRoute,noHTML[2]));
}
var sequence = Convert.ToString(row["Sequence"]);
var origID = -1;
if (GetTPoints.Rows.Count > 0)
{
origID = Convert.ToInt32(GetTPoints.Rows[i]["TPointsID"]);
var GetID = (SEPTA_DS.TimePointsTBLDataTable)tpta.GetDataByID(origID);
if (GetID.Rows.Count < 1)
{
origID = -1;
}
}
if (origID == -1)
{
int insertData = Convert.ToInt32(tpta.InsertTimePoints(category, agency, newRoute, direction, serviceKey, language, stopID, stopName, sequence));
}
else
{
int updateData = Convert.ToInt32(tpta.UpdateTimePoints(category, agency, newRoute, direction, serviceKey, language, stopID, stopName, sequence, origID));
}
skipped:
i++;
}
}
You can see how I check whether to insert or update around the bottom. I am using this method across other sections of this program and it works just fine. But in this case it is distorting my datatable immensely and I can't figure out why.
This is the bottom part of my table after inserting [no items currently within the database]:
This is the table after reuploading the CSV with data already existing within the table:
I am also getting this error when updating There is no row at position 2230.
What is going wrong in the code to cause this huge shift? I am just checking to see if the ID exists and if it does update rather than insert.
Also the reason i am using goto is because there are blank rows in the document that need to be skipped.

Is your TPointsID column, a auto-generated number? If so, since you are skipping the empty row, some referential integrity problem might be occuring,because of empty data in the skipped rows in the database.
From the error : There is no row at position 2230 , it is also understood that, because of the skipping you might be trying to access some non existent row in the datatable.
Also, if possible consider using the ADO.NET DataAdapter which has got the CRUD operation capability. You can find more about it at : http://support.microsoft.com/kb/308507