I'm having to write a app that effectively copies data from one databaseA.table to databaseB.table but there are a few fields in databaseB that aren't in databaseA.
I've come up with basic code below. The insert works and the update doesn't trow an error, however, the update doesn't actually update any records.
I've confirmed that the bcEmployee object in the update has the new values from databaseA like it should. The employee object is the record from databaseA.
Am I missing something to make this update?
BC_employee bcEmployee = new BC_employee();
bcEmployee.emp_id = employee.emp_id;
bcEmployee.emp_firstname = employee.emp_firstname;
bcEmployee.emp_lastname = employee.emp_lastname;
using (BCcontext ctx = new BCcontext())
{
var existBCemployee = ctx.employee.Find(employee.emp_id);
if (existBCemployee == null) //Insert
{
//Set default values that aren't in the original database
bcEmployee.emp_paystat = null;
bcEmployee.password = null;
bcEmployee.enroll_date = null;
ctx.employee.Add(bcEmployee);
}
else
{
ctx.Entry(existBCemployee).CurrentValues.SetValues(bcEmployee);
}
ctx.SaveChanges();
}
Related
I want to log new and modified records. This code works just fine for Modified Records.
But with Added records, there is an issue. Since it is new to the Database, there is not yet a primary key for it. So there is no way to log which record was added.
However, if I try to log the records after the save, the EntityState is no longer Added. So I don't know what was added.
The only solution I have been able to come up with is to save a list of the new records, and then after the save, then Log the changes. But that seems like a workaround.
Is there some way to resolve this?
private List<Event> LogChanges(EntityEntry entityEntry, Enums.TableNames tableName)
{
List<Event> result = new List<Event>();
var databaseValues = entityEntry.GetDatabaseValues();
foreach (var property in entityEntry.CurrentValues.Properties.Where(a=> a.Name !="TenantId"))
{
string original = databaseValues[property]?.ToString();
string current = entityEntry.CurrentValues[property]?.ToString();
if(!object.Equals(original,current))
{
result.Add(
new Event()
{
AppUserId = this._appUserProvider.CurrentAppUserId,
EventDate = DateTimeOffset.UtcNow,
EventTypeId = (int)Enums.EventTypes.Modified,
TenantId = databaseValues.GetValue<int>("TenantId"),
RecordId = databaseValues.GetValue<int>("Id"),
ColumnName = property.Name,
OriginalValue = original,
NewValue = current,
TableId = (int)tableName
});
}
}
return result;
}
This library adds triggers to EntityFrameworkCore. Using the Triggers it provides is a much cleaner way to accomplish the above.
I have an object with several really large string properties. In addition, it has a simple timestamp property.
What I trying to achieve is to update only timestamp property without getting the whole huge object to the server.
Eventually, I would like to use EF and to do in the most performant way something equivalent to this:
update [...]
set [...] = [...]
where [...]
Using the following, you can update a single column:
var yourEntity = new YourEntity() { Id = id, DateProp = dateTime };
using (var db = new MyEfContextName())
{
db.YourEntities.Attach(yourEntity);
db.Entry(yourEntity).Property(x => x.DateProp).IsModified = true;
db.SaveChanges();
}
OK, I managed to handle this. The solution is the same as proposed by Seany84, with the only addition of disabling validation, in order to overcome issue with required fields. Basically, I had to add the following line just before 'SaveChanges():
db.Configuration.ValidateOnSaveEnabled = false;
So, the complete solution is:
var yourEntity = new YourEntity() { Id = id, DateProp = dateTime };
using (var db = new MyEfContextName())
{
db.YourEntities.Attach(yourEntity);
db.Entry(yourEntity).Property(x => x.DateProp).IsModified = true;
db.Configuration.ValidateOnSaveEnabled = false;
db.SaveChanges();
}
I've been using JPA to insert entities into a database but I've run up against a problem where I need to do an insert and get the primary key of the record last inserted.
Using PostgreSQL I would use an INSERT RETURNING statement which would return the record id, but with an entity manager doing all this, the only way I know is to use SELECT CURRVAL.
So the problem becomes, I have several data sources sending data into a message driven bean (usually 10-100 messages at once from each source) via OpenMQ and inside this MDB I persists this to PostgreSQL via the entity manager. It's at this point I think there will be a "race condition like" effect of having so many inserts that I won't necessarily get the last record id using SELECT CURRVAL.
My MDB persists 3 entity beans via an entity manager like below.
Any help on how to better do this much appreciated.
public void onMessage(Message msg) {
Integer agPK = 0;
Integer scanPK = 0;
Integer lookPK = 0;
Iterator iter = null;
List<Ag> agKeys = null;
List<Scan> scanKeys = null;
try {
iag = (IAgBean) (new InitialContext()).lookup(
"java:comp/env/ejb/AgBean");
TextMessage tmsg = (TextMessage) msg;
// insert this into table only if doesn't exists
Ag ag = new Ag(msg.getStringProperty("name"));
agKeys = (List) (iag.getPKs(ag));
iter = agKeys.iterator();
if (iter.hasNext()) {
agPK = ((Ag) iter.next()).getId();
}
else {
// no PK found so not in dbase, insert new
iag.addAg(ag);
agKeys = (List) (iag.getPKs(ag));
iter = agKeys.iterator();
if (iter.hasNext()) {
agPK = ((Ag) iter.next()).getId();
}
}
// insert this into table always
iscan = (IScanBean) (new InitialContext()).lookup(
"java:comp/env/ejb/ScanBean");
Scan scan = new Scan();
scan.setName(msg.getStringProperty("name"));
scan.setCode(msg.getIntProperty("code"));
iscan.addScan(scan);
scanKeys = (List) iscan.getPKs(scan);
iter = scanKeys.iterator();
if (iter.hasNext()) {
scanPK = ((Scan) iter.next()).getId();
}
// insert into this table the two primary keys above
ilook = (ILookBean) (new InitialContext()).lookup(
"java:comp/env/ejb/LookBean");
Look look = new Look();
if (agPK.intValue() != 0 && scanPK.intValue() != 0) {
look.setAgId(agPK);
look.setScanId(scanPK);
ilook.addLook(look);
}
// ...
The JPA spec requires that after persist, the entity be populated with a valid ID if an ID generation strategy is being used. You don't have to do anything.
I'm new to the entity framework and I'm really confused about how savechanges works. There's probably a lot of code in my example which could be improved, but here's the problem I'm having.
The user enters a bunch of picks. I make sure the user hasn't already entered those picks.
Then I add the picks to the database.
var db = new myModel()
var predictionArray = ticker.Substring(1).Split(','); // Get rid of the initial comma.
var user = Membership.GetUser();
var userId = Convert.ToInt32(user.ProviderUserKey);
// Get the member with all his predictions for today.
var memberQuery = (from member in db.Members
where member.user_id == userId
select new
{
member,
predictions = from p in member.Predictions
where p.start_date == null
select p
}).First();
// Load all the company ids.
foreach (var prediction in memberQuery.predictions)
{
prediction.CompanyReference.Load();
}
var picks = from prediction in predictionArray
let data = prediction.Split(':')
let companyTicker = data[0]
where !(from i in memberQuery.predictions
select i.Company.ticker).Contains(companyTicker)
select new Prediction
{
Member = memberQuery.member,
Company = db.Companies.Where(c => c.ticker == companyTicker).First(),
is_up = data[1] == "up", // This turns up and down into true and false.
};
// Save the records to the database.
// HERE'S THE PART I DON'T UNDERSTAND.
// This saves the records, even though I don't have db.AddToPredictions(pick)
foreach (var pick in picks)
{
db.SaveChanges();
}
// This does not save records when the db.SaveChanges outside of a loop of picks.
db.SaveChanges();
foreach (var pick in picks)
{
}
// This saves records, but it will insert all the picks exactly once no matter how many picks you have.
//The fact you're skipping a pick makes no difference in what gets inserted.
var counter = 1;
foreach (var pick in picks)
{
if (counter == 2)
{
db.SaveChanges();
}
counter++;
}
I've tested and the SaveChanges doesn't even have to be in the loop.
The below code works, too.
foreach (var pick in picks)
{
break;
}
db.SaveChanges()
There's obviously something going on with the context I don't understand. I'm guessing I've somehow loaded my new picks as pending changes, but even if that's true I don't understand I have to loop over them to save changes.
Can someone explain this to me?
Here's updated working code based on Craig's responses:
1) Remove the Type then loop over the results and populate new objects.
var picks = (from prediction in predictionArray
let data = prediction.Split(':')
let companyTicker = data[0]
where !(from i in memberQuery.predictions
select i.Company.ticker).Contains(companyTicker)
select new //NO TYPE HERE
{
Member = memberQuery.member,
Company = db.Companies.Where(c => c.ticker == companyTicker).First(),
is_up = data[1] == "up", // This turns up and down into true and false.
}).ToList();
foreach (var prediction in picks)
{
if (includePrediction)
{
var p = new Prediction{
Member = prediction.Member,
Company = prediction.Company,
is_up = prediction.is_up
};
db.AddToPredictions(p);
}
}
2) Or if I don't want the predictions to be saved, I can detach the predictions.
foreach (var prediction in picks) {
if (excludePrediction)
{
db.Detach(prediction)
}
}
The reason is here:
select new Prediction
{
Member = memberQuery.member,
These lines will (once the IEnumerable is iterated; LINQ is lazy) :
Instantiate a new Prediction
Associate that Prediction with an existing Member, *which is attached to db.
Associating an instance of an entity with an attached entity automatically adds that entity to the context of the associated, attached entity.
So as soon as you start iterating over predictionArray, the code above executes and you have a new entity in your context.
I am attempting to add some entities that I have created. When I try and add the entity in question to the set (see code below) I get the following error:
"The object could not be added or attached because its EntityReference has an EntityKey property value that does not match the EntityKey for this object."
I can't tell what entitykey it's referring to though. Here is the code, there is probably a much better way to pull this off as well:
public Internship CreateInternship(Internship internshipToCreate)
{
try
{
Contact contactToCreate = new Contact();
contactToCreate.Fax = internshipToCreate.contacts.Fax;
contactToCreate.Extension = internshipToCreate.contacts.Extension;
contactToCreate.FirstName = internshipToCreate.contacts.FirstName;
contactToCreate.MiddleName = internshipToCreate.contacts.MiddleName;
contactToCreate.LastName = internshipToCreate.contacts.LastName;
contactToCreate.PhoneNumber = internshipToCreate.contacts.PhoneNumber;
contactToCreate.StreetAddress = internshipToCreate.contacts.StreetAddress;
contactToCreate.PostalCode = internshipToCreate.contacts.PostalCode;
contactToCreate.ContactEmail = internshipToCreate.contacts.ContactEmail;
contactToCreate.statesReference.EntityKey =
new EntityKey("InternshipEntities.StateSet", "ID", internshipToCreate.contacts.states.ID);
contactToCreate.countriesReference.EntityKey =
new EntityKey("InternshipEntities.CountrySet", "ID", internshipToCreate.contacts.countries.ID);
_internshipEntities.AddToContactSet(contactToCreate);
_internshipEntities.SaveChanges();
try
{
Availability availabilityToCreate = new Availability();
availabilityToCreate.StartDate = internshipToCreate.availability.StartDate;
availabilityToCreate.EndDate = internshipToCreate.availability.EndDate;
availabilityToCreate.Negotiable = internshipToCreate.availability.Negotiable;
_internshipEntities.AddToAvailabilitySet(availabilityToCreate);
_internshipEntities.SaveChanges();
try
{
internshipToCreate.contactsReference.EntityKey =
new EntityKey("InternshipEntities.ContactSet", "ID", contactToCreate.ID);
internshipToCreate.availabilityReference.EntityKey =
new EntityKey("InternshipEntities.AvailabilitySet", "ID", availabilityToCreate.ID);
internshipToCreate.classificationsReference.EntityKey =
new EntityKey("InternshipEntities.ClassificationSet", "ID", internshipToCreate.classifications.ID);
internshipToCreate.educationReference.EntityKey =
new EntityKey("InternshipEntities.EducationSet", "ID", internshipToCreate.education.ID);
_internshipEntities.AddToInternshipSet(internshipToCreate); //exception here
_internshipEntities.SaveChanges();
return internshipToCreate;
}
catch(Exception e)
{
throw e;
}
}
catch(Exception e)
{
throw e;
}
}
catch(Exception e)
{
throw e;
}
}
There is no other information given besides the error when I trace through so I'm not even sure which Key is the issue.
EDIT: Here is the version that ended up working:
using (TransactionScope scope = new TransactionScope())
{
try
{
Contact contactToCreate = new Contact();
Availability availabilityToCreate = new Availability();
Internship i = new Internship();
// Set the contact entity values;
contactToCreate.Fax = internshipToCreate.contacts.Fax;
//...
//ommited for brevity
//...
contactToCreate.ContactEmail = internshipToCreate.contacts.ContactEmail;
// Set the contact entity references to existing tables
contactToCreate.statesReference.EntityKey =
new EntityKey("InternshipEntities.StateSet", "ID", internshipToCreate.contacts.states.ID);
contactToCreate.countriesReference.EntityKey =
new EntityKey("InternshipEntities.CountrySet", "ID", internshipToCreate.contacts.countries.ID);
// Add contact
_internshipEntities.AddToContactSet(contactToCreate);
// Set the availability entity values;
availabilityToCreate.StartDate = internshipToCreate.availability.StartDate;
availabilityToCreate.EndDate = internshipToCreate.availability.EndDate;
availabilityToCreate.Negotiable = internshipToCreate.availability.Negotiable;
// Add availability
_internshipEntities.AddToAvailabilitySet(availabilityToCreate);
//Add contact and availability entities to new internship entity
i.contacts = contactToCreate;
i.availability = availabilityToCreate;
// Set internship entity values;
i.UserID = internshipToCreate.UserID;
//...
//ommited for brevity
//...
i.Created = DateTime.Now;
// Set the internship entity references to existing tables
i.classificationsReference.EntityKey =
new EntityKey("InternshipEntities.ClassificationSet", "ID", internshipToCreate.classifications.ID);
i.educationReference.EntityKey =
new EntityKey("InternshipEntities.EducationSet", "ID", internshipToCreate.education.ID);
// Add internship and save
_internshipEntities.AddToInternshipSet(i);
_internshipEntities.SaveChanges();
//commit transaction
scope.Complete();
return internshipToCreate;
}
catch (Exception e)
{
throw e;
}
}
Hallo,
although I'm not sure what the problem is I have a suggestion. The Internship object that you are passing into method (internshipToCreate) is used to transfer values to other entities (Contact, Availability) that you instantiated inside of the method, and their creation works just fine.
Maybe you should try to do the same with Internship? Create new Internship object and set all values you have by taking them from internshipToCreate object, and than that newly created object pass to the _internshipEntities.AddToInternshipSet method.
It is possible that you've set some values on internshipToCreate object that you needed for other purposes, and that some of those is actually causing the exception.
And, I don't know what you business logic is, but it would be better if you put all under one transaction, because like this it may happen that first two entities are created, and third one not.
This code isn't making a lot of sense to me. In two cases, you're going through an EntityKey when you could just assign an object reference. I.e, change this:
internshipToCreate.contactsReference.EntityKey =
new EntityKey("InternshipEntities.ContactSet", "ID", contactToCreate.ID);
internshipToCreate.availabilityReference.EntityKey =
new EntityKey("InternshipEntities.AvailabilitySet", "ID", availabilityToCreate.ID);
...to:
internshipToCreate.contacts = contactToCreate;
internshipToCreate.availability = availabilityToCreate;
In the other two cases you seem to be attempting to assign the ID of the object which is already there. These two lines, even if successful, it seems to me, would do nothing:
internshipToCreate.classificationsReference.EntityKey =
new EntityKey("InternshipEntities.ClassificationSet", "ID", internshipToCreate.classifications.ID);
internshipToCreate.educationReference.EntityKey =
new EntityKey("InternshipEntities.EducationSet", "ID", internshipToCreate.education.ID);
So you can just get rid of them.
What happens when you make these two changes?