I'm trying to save only changed entities.
If I remove this if:
if (!period.IsSame(_context.Periods.First(p => p.ID == period.ID)))
everything is fine.
But if I keep it, on the statement _context.Attach(period); or same if I use Update, I get an error:
InvalidOperationException: The instance of entity type 'Period' cannot be tracked because another instance with the same key value for {'ID'} is already being tracked.
I don't know how test that it's really modified.
public async Task<IActionResult> OnPostAsync(List<Period> periods)
{
if (!ModelState.IsValid)
{
return Page();
}
// _context.Periods.Add(Period);
int i = 0;
foreach (var period in periods)
{
TimeOnly startTime = TimeOnly.Parse(Request.Form["StartTime" + i].ToString());
TimeOnly endTime = TimeOnly.Parse(Request.Form["EndTime" + i].ToString());
period.StartHour = startTime.Hour;
period.StartMinute = startTime.Minute;
period.EndHour = endTime.Hour;
period.EndMinute = endTime.Minute;
period.StatusDate = DateTime.Now;
// if it already exists
if (period.ID > 0)
{
// if modified
if (!period.IsSame(_context.Periods.First(p => p.ID == period.ID)))
{
_context.Attach(period);
if (period.Delete)
{
period.Status = (int)Status.deleted;
}
else
{
period.Status = (int)Status.modified;
}
}
}
// if new
else
{
period.Status = (int)Status.created;
_context.Attach(period);
}
i++;
}
await _context.SaveChangesAsync();
return RedirectToPage("./Periods");
}
I have tried both update and attach. I have search for entity tracking but it seems to be detached as soon as it's on a webpage
EF uses concept of change tracking to determine what should be done with entities. By default querying data will lead to context starting to track it hence the exception. You can mitigate it by disabling tracking by default, for example using .AsNoTracking():
if (!period.IsSame(_context.Periods.AsNoTracking().First(p => p.ID == period.ID)))
{
// ...
}
But this is not very advisable approach, due to multiple reasons - possibly change tracker will not detect any changes and you will need to handle that manually, and bigger reason - you will be querying database in a loop which is bad for application performance. Just fetch everything from the database and update it accordingly:
var existingPeriods = await _context.Periods
.Where(p => periods.Select(p => p.ID).Contains(p.ID))
.ToListAsync(); // or ToDictionaryAsync if there a lot of the periods
foreach (var period in periods)
{
var existing = existingPeriods.FirstOrDefault(p => p.ID == period.ID);
if (existing != null)
{
// maybe throw if period.ID != 0
// update data in existing
existing. ... = ...;
}
else
{
// if new ...
_context.Periods.Add(period);
}
await _context.SaveChangesAsync();
}
Related
Seems that the SaveChanges() only saves the last object added into the table:
static void Main(string[] args)
{
Category c = new Category();
using (GenericDBEntities db = new GenericDBEntities())
{
foreach (Match i in db.Matches)
{
if (!db.Categories.Any())
{
c.CategoryInternalId = i.CategoryId;
c.CategoryName = i.CategoryName;
c.SportId = i.SportId;
db.Categories.Add(c);
}
else
{
foreach (Category a in db.Categories)
{
if (i.CategoryId != a.CategoryInternalId)
{
c.CategoryInternalId = i.CategoryId;
c.CategoryName = i.CategoryName;
c.SportId = i.SportId;
db.Categories.Add(c);
}
else
{
return;
}
}
}
}
db.SaveChanges();
I have tried it in a few different ways which all have the same or less result, the for loop saves them all, no matter if condition is met or not. Why is it only saving the last object of the Match table? What am I missing?
Clarification: The task is to go through Match table, which has duplicate CategoryIDs and to, if it is not already in the Category table, add it, so it won't store duplicates again, the problem is Category table is initially empty, hence the newbie logic, still learnin'!
You need to create the Category object for each inserted category, otherwise you have just one category object which you are editing all the time and hence just this one (the last edit) will be saved to the DB.
If you want to add all new categories from Matches based on CategoryId you can use something like this:
using (GenericDBEntities db = new GenericDBEntities())
{
var newCategories = db.Matches
.Where(m => !db.Categories
.Select(c => c.CategoryInternalId)
.Distinct().Contains(m.CategoryId))
.Select(m => new { m.CategoryId, m.CategoryName, m.SportId })
.GroupBy(m => m.otherid)
.Select(g => g.FirstOrDefault())
.ToList();
foreach (var i in newCategories)
{
var c = new Category()
{
CategoryInternalId = i.CategoryId,
CategoryName = i.CategoryName,
SportId = i.SportId
};
db.Categories.Add(c);
}
db.SaveChanges();
}
Now you'll get all the new categories from the Matches table in one go. This is a first draft, meaning that the performance can be further tuned if needed.
I am using Redis with StackExchange.Redis. I have multiple threads that will at some point access and edit the value of the same key, so I need to synchronize the manipulation of the data.
Looking at the available functions, I see that there are two functions, TakeLock and ReleaseLock. However, these functions take both a key and a value parameter rather than the expected single key to be locked. The intellisene documentation and source on GitHub don't explain how to use the LockTake and LockRelease functions or what to pass in for the key and value parameters.
Q: What is the correct usage of LockTake and LockRelease in StackExchange.Redis?
Pseudocode example of what I'm aiming to do:
//Add Items Before Parallel Execution
redis.StringSet("myJSONKey", myJSON);
//Parallel Execution
Parallel.For(0, 100, i =>
{
//Some work here
//....
//Lock
redis.LockTake("myJSONKey");
//Manipulate
var myJSONObject = redis.StringGet("myJSONKey");
myJSONObject.Total++;
Console.WriteLine(myJSONObject.Total);
redis.StringSet("myJSONKey", myNewJSON);
//Unlock
redis.LockRelease("myJSONKey");
//More work here
//...
});
There are 3 parts to a lock:
the key (the unique name of the lock in the database)
the value (a caller-defined token which can be used both to indicate who "owns" the lock, and to check that releasing and extending the lock is being done correctly)
the duration (a lock intentionally is a finite duration thing)
If no other value comes to mind, a guid might make a suitable "value". We tend to use the machine-name (or a munged version of the machine name if multiple processes could be competing on the same machine).
Also, note that taking a lock is speculative, not blocking. It is entirely possible that you fail to obtain the lock, and hence you may need to test for this and perhaps add some retry logic.
A typical example might be:
RedisValue token = Environment.MachineName;
if(db.LockTake(key, token, duration)) {
try {
// you have the lock do work
} finally {
db.LockRelease(key, token);
}
}
Note that if the work is lengthy (a loop, in particular), you may want to add some occasional LockExtend calls in the middle - again remembering to check for success (in case it timed out).
Note also that all individual redis commands are atomic, so you don't need to worry about two discreet operations competing. For more complexing multi-operation units, transactions and scripting are options.
There is my part of code for lock->get->modify(if required)->unlock actions with comments.
public static T GetCachedAndModifyWithLock<T>(string key, Func<T> retrieveDataFunc, TimeSpan timeExpiration, Func<T, bool> modifyEntityFunc,
TimeSpan? lockTimeout = null, bool isSlidingExpiration=false) where T : class
{
int lockCounter = 0;//for logging in case when too many locks per key
Exception logException = null;
var cache = Connection.GetDatabase();
var lockToken = Guid.NewGuid().ToString(); //unique token for current part of code
var lockName = key + "_lock"; //unique lock name. key-relative.
T tResult = null;
while ( lockCounter < 20)
{
//check for access to cache object, trying to lock it
if (!cache.LockTake(lockName, lockToken, lockTimeout ?? TimeSpan.FromSeconds(10)))
{
lockCounter++;
Thread.Sleep(100); //sleep for 100 milliseconds for next lock try. you can play with that
continue;
}
try
{
RedisValue result = RedisValue.Null;
if (isSlidingExpiration)
{
//in case of sliding expiration - get object with expiry time
var exp = cache.StringGetWithExpiry(key);
//check ttl.
if (exp.Expiry.HasValue && exp.Expiry.Value.TotalSeconds >= 0)
{
//get only if not expired
result = exp.Value;
}
}
else //in absolute expiration case simply get
{
result = cache.StringGet(key);
}
//"REDIS_NULL" is for cases when our retrieveDataFunc function returning null (we cannot store null in redis, but can store pre-defined string :) )
if (result.HasValue && result == "REDIS_NULL") return null;
//in case when cache is epmty
if (!result.HasValue)
{
//retrieving data from caller function (from db from example)
tResult = retrieveDataFunc();
if (tResult != null)
{
//trying to modify that entity. if caller modifyEntityFunc returns true, it means that caller wants to resave modified entity.
if (modifyEntityFunc(tResult))
{
//json serialization
var json = JsonConvert.SerializeObject(tResult);
cache.StringSet(key, json, timeExpiration);
}
}
else
{
//save pre-defined string in case if source-value is null.
cache.StringSet(key, "REDIS_NULL", timeExpiration);
}
}
else
{
//retrieve from cache and serialize to required object
tResult = JsonConvert.DeserializeObject<T>(result);
//trying to modify
if (modifyEntityFunc(tResult))
{
//and save if required
var json = JsonConvert.SerializeObject(tResult);
cache.StringSet(key, json, timeExpiration);
}
}
//refresh exiration in case of sliding expiration flag
if(isSlidingExpiration)
cache.KeyExpire(key, timeExpiration);
}
catch (Exception ex)
{
logException = ex;
}
finally
{
cache.LockRelease(lockName, lockToken);
}
break;
}
if (lockCounter >= 20 || logException!=null)
{
//log it
}
return tResult;
}
and usage :
public class User
{
public int ViewCount { get; set; }
}
var cachedAndModifiedItem = GetCachedAndModifyWithLock<User>(
"MyAwesomeKey", //your redis key
() => // callback to get data from source in case if redis's store is empty
{
//return from db or kind of that
return new User() { ViewCount = 0 };
},
TimeSpan.FromMinutes(10), //object expiration time to pass in Redis
user=> //modify object callback. return true if you need to save it back to redis
{
if (user.ViewCount< 3)
{
user.ViewCount++;
return true; //save it to cache
}
return false; //do not update it in cache
},
TimeSpan.FromSeconds(10), //lock redis timeout. if you will have race condition situation - it will be locked for 10 seconds and wait "get_from_db"/redis read/modify operations done.
true //is expiration should be sliding.
);
That code can be improved (for example, you can add transactions for less count call to cache and etc), but i glad it will be helpfull for you.
This method is not my best, but had a circular reference issue going on so slapped it together last minute. For some reason, even though I'm evicting the original referenced order on the detail object, I've still got another association with the session. Should I use a get instead? Or even better is there a way to say evict ALL orders with ID = x ?
public DetailDTO SaveNewDetailToOrder(DetailDTO detailDTO)
{
var detailReturn = new DetailDTO();
try
{
var order = LoadOrderById(detailDTO.OrderId);
var previousStatus = issue.CurrentDetailStatus;
if (previousStatus != null && detailDTO.Status.Id != previousStatus.Id)
{
var detail = Mapper.Map<DetailDTO, Detail>(detailDTO);
_orderRepository.EvictOrder(detail.DetailOrder);
order.Details.Add(detailDTO);
order.IsEscalated = false;
order.DormantDate = detailDTO.CreatedTime;
var orderReturn = SaveOrder(order); ///Error Here
if (orderReturn.IsActionSuccessful)
{
detailReturn =
orderReturn.Details.DTOObjects.OrderByDescending(x => x.CreatedTime).First();
SendStatusChangeEmail(orderReturn);
}
}
else
{
detailReturn = _detailService.SaveDetail(detailDTO);
}
}
catch (Exception ex)
{
throw ServiceErrorMessage(ex, detailReturn);
}
return detailReturn ;
}
You can access session objects and use then whatever you like
session.GetSessionImplementation().PersistenceContext.EntityEntries
but if I were you i would make sure that i'm evicting the right object and spend some time on debuging. Knowing what is going on is better than searching for workarounds
foreach (var e in session.GetSessionImplementation().PersistenceContext.EntityEntries.Values.OfType<EntityType>().Where(<condition>))
{
session.Evict(e);
}
I have a entity record which is shared with or more users. I would like to unshare this record when Deactivate it. I want to do that in Plugin. But I can't understand how to get all users from sharing list who have access to this record. How to do that?
Here is my code snippet:
protected void ExecutePostPersonSetStateDynamicEntity(LocalPluginContext localContext)
{
if (localContext == null)
{
throw new ArgumentNullException("localContext");
}
var context = localContext.PluginExecutionContext;
var targetEntity = (Entity)context.InputParameters["EntityMoniker"];
var state = (OptionSetValue)context.InputParameters["State"];
var columns = new ColumnSet(new[] { "statecode" });
var retrivedEntity = localContext.OrganizationService.Retrieve(targetEntity.LogicalName, targetEntity.Id, columns);
if (state.Value == 1)
{
RevokeAccessRequest revokeRequest = new RevokeAccessRequest()
{
Target = new EntityReference(personEntity.LogicalName, personEntity.Id),
Revokee = new EntityReference(neededEntity.LogicalName, needed.Id)
};
// Execute the request.
}
}
As you can see, I need an entity "neededEntity", I don't know how to get it from "targetEntity" or "retrievedEntity".
You need to use a RetrieveSharedPrincipalsAndAccessRequest
http://msdn.microsoft.com/en-us/library/microsoft.crm.sdk.messages.retrievesharedprincipalsandaccessrequest.aspx
You can start from the included example, basically inside the foreach you call your RevokeAcessRequest
I'm having a Entity-Set Countries, reflecting a database table '<'char(2),char(3),nvarchar(50> in my database.
Im having a parser that returns a Country[] array of parsed countries, and is having issues with getting it updated in the right way. What i want is: Take the array of countries, for those countries not already in the database insert them, and those existing update if any fields is different. How can this be done?
void Method(object sender, DocumentLoadedEvent e)
{
var data = e.ParsedData as Country[];
using(var db = new DataContractEntities)
{
//Code missing
}
}
I was thinking something like
for(var c in data.Except(db.Countries)) but it wount work as it compares on wronge fields.
Hope anyone have had this issues before, and have a solution for me. If i cant use the Country object and insert/update an array of them easy, i dont see much benefict of using the framework, as from performers i think its faster to write a custom sql script that inserts them instead of ect checking if an country is already in the database before inserting?
Solution
See answer of post instead.
I added override equals to my country class:
public partial class Country
{
public override bool Equals(object obj)
{
if (obj is Country)
{
var country = obj as Country;
return this.CountryTreeLetter.Equals(country.CountryTreeLetter);
}
return false;
}
public override int GetHashCode()
{
int hash = 13;
hash = hash * 7 + (int)CountryTreeLetter[0];
hash = hash * 7 + (int)CountryTreeLetter[1];
hash = hash * 7 + (int)CountryTreeLetter[2];
return hash;
}
}
and then did:
var data = e.ParsedData as Country[];
using (var db = new entities())
{
foreach (var item in data.Except(db.Countries))
{
db.AddToCountries(item);
}
db.SaveChanges();
}
I would do it straightforward:
void Method(object sender, DocumentLoadedEvent e)
{
var data = e.ParsedData as Country[];
using(var db = new DataContractEntities)
{
foreach(var country in data)
{
var countryInDb = db.Countries
.Where(c => c.Name == country.Name) // or whatever your key is
.SingleOrDefault();
if (countryInDb != null)
db.Countries.ApplyCurrentValues(country);
else
db.Countries.AddObject(country);
}
db.SaveChanges();
}
}
I don't know how often your application must run this or how many countries your world has. But I have the feeling that this is nothing where you must think about sophisticated performance optimizations.
Edit
Alternative approach which would issue only one query:
void Method(object sender, DocumentLoadedEvent e)
{
var data = e.ParsedData as Country[];
using(var db = new DataContractEntities)
{
var names = data.Select(c => c.Name);
var countriesInDb = db.Countries
.Where(c => names.Contains(c.Name))
.ToList(); // single DB query
foreach(var country in data)
{
var countryInDb = countriesInDb
.SingleOrDefault(c => c.Name == country.Name); // runs in memory
if (countryInDb != null)
db.Countries.ApplyCurrentValues(country);
else
db.Countries.AddObject(country);
}
db.SaveChanges();
}
}
The modern form, using later EF versions would be:
context.Entry(record).State = (AlreadyExists ? EntityState.Modified : EntityState.Added);
context.SaveChanges();
AlreadyExists can come from checking the key or by querying the database to see whether the item already exists there.
You can implement your own IEqualityComparer<Country> and pass that to the Except() method. Assuming your Country object has Id and Name properties, one example of that implementation could look like this:
public class CountryComparer : IEqualityComparer<Country>
{
public bool Equals(Country x, Country y)
{
return x.Name.Equals(y.Name) && (x.Id == y.Id);
}
public int GetHashCode(Country obj)
{
return string.Format("{0}{1}", obj.Id, obj.Name).GetHashCode();
}
}
and use it as
data.Countries.Except<Country>(db, new CountryComparer());
Although, in your case it looks like you just need to extract new objects, you can use var newCountries = data.Where(c => c.Id == Guid.Empty); if your Id is Guid.
The best way is to inspect the Country.EntityState property and take actions from there regarding on value (Detached, Modified, Added, etc.)
You need to provide more information on what your data collection contains i.e. are the Country objects retrieved from a database through the entityframework, in which case their context can be tracked, or are you generating them using some other way.
I am not sure this will be the best solution but I think you have to get all countries from DB then check it with your parsed data
void Method(object sender, DocumentLoadedEvent e)
{
var data = e.ParsedData as Country[];
using(var db = new DataContractEntities)
{
List<Country> mycountries = db.Countries.ToList();
foreach(var PC in data)
{
if(mycountries.Any( C => C.Name==PC.Name ))
{
var country = mycountries.Any( C => C.Name==PC.Name );
//Update it here
}
else
{
var newcountry = Country.CreateCountry(PC.Name);//you must provide all required parameters
newcountry.Name = PC.Name;
db.AddToCountries(newcountry)
}
}
db.SaveChanges();
}
}