Why isn't the exception triggered? Linq's "Any()" is not considering the new entries?
MyContext db = new MyContext();
foreach (string email in {"asdf#gmail.com", "asdf#gmail.com"})
{
Person person = new Person();
person.Email = email;
if (db.Persons.Any(p => p.Email.Equals(email))
{
throw new Exception("Email already used!");
}
db.Persons.Add(person);
}
db.SaveChanges()
Shouldn't the exception be triggered on the second iteration?
The previous code is adapted for the question, but the real scenario is the following:
I receive an excel of persons and I iterate over it adding every row as a person to db.Persons, checking their emails aren't already used in the db. The problem is when there are repeated emails in the worksheet itself (two rows with the same email)
Yes - queries (by design) are only computed against the data source. If you want to query in-memory items you can also query the Local store:
if (db.Persons.Any(p => p.Email.Equals(email) ||
db.Persons.Local.Any(p => p.Email.Equals(email) )
However - since YOU are in control of what's added to the store wouldn't it make sense to check for duplicates in your code instead of in EF? Or is this just a contrived example?
Also, throwing an exception for an already existing item seems like a poor design as well - exceptions can be expensive, and if the client does not know to catch them (and in this case compare the message of the exception) they can cause the entire program to terminate unexpectedly.
A call to db.Persons will always trigger a database query, but those new Persons are not yet persisted to the database.
I imagine if you look at the data in debug, you'll see that the new person isn't there on the second iteration. If you were to set MyContext db = new MyContext() again, it would be, but you wouldn't do that in a real situation.
What is the actual use case you need to solve? This example doesn't seem like it would happen in a real situation.
If you're comparing against the db, your code should work. If you need to prevent dups being entered, it should happen elsewhere - on the client or checking the C# collection before you start writing it to the db.
Related
Good Morning.
I'm starting to learn some mongo right now.
I'm facing this problem right now, and i'm start to think if this is the best approach to resolve this "task", or if is bettert to turn around and write another way to solve this "problem".
My goal is to iterate a simple map of values (key) and vector\array (values)
My test map will be recived by a rest layer.
{
"1":["1","2","3"]
}
now after some logic, i need to use the Dao in order to look into db.
The Key will be "realm", the value inside vector are "castle".
Every Realm have some castle and every castle have some "rules".
I need to find every rules for each avaible combination of realm-castle.
AccessLevel is a pojo labeled by #Document annotation and it will have various params, such as castle and realm (both simple int)
So the idea will be to iterate a map and write a long query for every combination of key-value.
public AccessLevel searchAccessLevel(Map<String,Integer[]> request){
Query q = new Query();
Criteria c = new Criteria();
request.forEach((k,v)-> {
for (int i: Arrays.asList(v)
) {
q.addCriteria(c.andOperator(
Criteria.where("realm").is(k),
Criteria.where("castle").is(v))
);
}
});
List<AccessLevel> response=db.find(q,AccessLevel.class);
for (AccessLevel x: response
) {
System.out.println(x.toString());
}
As you can see i'm facing an error concerning $and.
Due to limitations of the org.bson.Document, you can't add a second '$and' expression specified as [...]
it seems mongo can't handle various $and, something i'm pretty used to abuse over sql
select * from a where id =1 and id=2 and id=3 and id=4
(not the best, sincei can use IN(), but sql allow me)
So, the point is: mongo can actualy work in this way and i need to dig more into the problem, or i need to do another approach, like using criterion.in(), and make N interrogation via mongotemplate one for every key in my Map?
I'm using EF 5 with Oracle database.
I'm doing a select count in a table with a specific parameter. When I'm using EF, the query returns the value 31, as expected, But the result takes about 10 seconds to be returned.
using (var serv = new Aperam.SIP.PXP.Negocio.Modelos.SIP_PA())
{
var teste = (from ens in serv.PA_ENSAIOS_UM
where ens.COD_IDENT_UNMET == "FBLDY3840"
select ens).Count();
}
If I execute the simple query bellow the result is the same (31), but the result is showed in 500 milisecond.
SELECT
count(*)
FROM
PA_ENSAIOS_UM
WHERE
COD_IDENT_UNMET 'FBLDY3840'
There are a way to improve the performance when I'm using EF?
Note: There are 13.000.000 lines in this table.
Here are some things you can try:
Capture the query that is being generated and see if it is the same as the one you are using. Details can be found here, but essentially, you will instantiate your DbContext (let's call it "_context") and then set the Database.Log property to be the logging method. It's fine if this method doesn't actually do anything--you can just set a breakpoint in there and see what's going on.
So, as an example: define a logging function (I have a static class called "Logging" which uses nLog to write to files)
public static void LogQuery(string queryData)
{
if (string.IsNullOrWhiteSpace(queryData))
return;
var message = string.Format("{0}{1}",
queryData.Trim().Contains(Environment.NewLine) ?
Environment.NewLine : "", queryData);
_sqlLogger.Info(message);
_genLogger.Trace($"EntityFW query (len {message.Length} chars)");
}
Then when you create your context point to LogQuery:
_context.Database.Log = Logging.LogQuery;
When you do your tests, remember that often the first run is the slowest because the server has to actually do the work, but on the subsequent runs, it often uses cached data. Try running your tests 2-3 times back to back and see if they don't start to run in the same time.
I don't know if it generates the same query or not, but try this other form (which should be functionally equivalent, but may provide better time)
var teste = serv.PA_ENSAIOS_UM.Count(ens=>ens.COD_IDENT_UNMET == "FBLDY3840");
I'm wondering if the version you have pulls data from the DB and THEN counts it. If so, this other syntax may leave all the work to be done at the server, where it belongs. Not sure, though, esp. since I haven't ever used EF with Oracle and I don't know if it behaves the same as SQL or not.
Considering a Spring Boot, neo4j environment with Spring-Data-neo4j-4 I want to make a delete and get an error message when it fails to delete.
My problem is since the Repository.delete() returns void I have no ideia if the delete modified anything or not.
First question: is there any way to get the last query affected lines? for example in plsql I could do SQL%ROWCOUNT
So anyway, I tried the following code:
public void deletesomething(Long somethingId) {
somethingRepository.delete(getExistingsomething(somethingId).getId());
}
private something getExistingsomething(Long somethingId, int depth) {
return Optional.ofNullable(somethingRepository.findOne(somethingId, depth))
.orElseThrow(() -> new somethingNotFoundException(somethingId));
}
In the code above I query the database to check if the value exist before I delete it.
Second question: do you recommend any different approach?
So now, just to add some complexity, I have a cluster database and db1 can only Create, Update and Delete, and db2 and db3 can only Read (this is ensured by the cluster sockets). db2 and db3 will receive the data from db1 from the replication process.
For what I seen so far replication can take up to 90s and that means that up to 90s the database will have a different state.
Looking again to the code above:
public void deletesomething(Long somethingId) {
somethingRepository.delete(getExistingsomething(somethingId).getId());
}
in debug that means:
getExistingsomething(somethingId).getId() // will hit db2
somethingRepository.delete(...) // will hit db1
and so if replication has not inserted the value in db2 this code wil throw the exception.
the second question is: without changing those sockets is there any way for me to delete and give the correct response?
This is not currently supported in Spring Data Neo4j, if you wish please open a feature request.
In the meantime, perhaps the easiest work around is to fall down to the OGM level of abstraction.
Create a class that is injected with org.neo4j.ogm.session.Session
Use the following method on Session
Example: (example is in Kotlin, which was on hand)
fun deleteProfilesByColor(color : String)
{
var query = """
MATCH (n:Profile {color: {color}})
DETACH DELETE n;
"""
val params = mutableMapOf(
"color" to color
)
val result = session.query(query, params)
val statistics = result.queryStatistics() //Use these!
}
Time to leave the shy mode behind and make my first post on stackoverflow.
After doing loads of research (plugins, performance, indexes, types of update, friends) and after trying several approaches I was unable to find a proper answer/solution.
So if possible I would like to get your feedback/help in a Microsoft Dynamics CRM 2013/2015 plugin performance issue (or coding technique)
Scenario:
Microsoft Dynamics CRM 2013/2015
2 Entities with Relationship 1:N
EntityA
EntityB
EntityB has the following columns:
Id | EntityAId | ColumnDemoX (decimal) | ColumnDemoY (currency)
Entity A has: 500 records
Entity B has: 150 records per each Entity A record. So 500*150 = 75000 records.
Objective:
Create a Post Entity A Plugin Update to "mimic" the following SQL command
Update EntityB
Set ColumnDemoX = (some quantity), ColumnDemoY = (some quantity) * (some value)
Where EntityAId = (some id)
One approach could be:
using (var serviceContext = new XrmServiceContext(service))
{
var query = from a in serviceContext.EntityASet
where a.EntityAId.Equals(someId)
select a;
foreach (EntityA entA in query)
{
entA.ColumnDemoX = (some quantity);
serviceContext.UpdateObject(entA);
}
serviceContext.SaveChanges();
}
Problem:
The foreach for 150 records in the post plugin update will take 20 secs or more.
While the
Update EntityB Set ColumnDemoX = (some quantity), ColumnDemoY = (some quantity) * (some value) Where EntityAId = (some id)
it will take 0.00001 secs
Any suggestion/solution?
Thank you all for reading.
H
You can use the ExecuteMultipleRequest, when you iterate the 150 entities, save the entities you need to update and after that call the request. If you do this, you only call the service once, that's very good for the perfomance.
If your process could be bigger and bigger, then you should think making it asynchronous as a plug-in or a custom activity workflow.
This is an example:
// Create an ExecuteMultipleRequest object.
requestWithResults = new ExecuteMultipleRequest()
{
// Assign settings that define execution behavior: continue on error, return responses.
Settings = new ExecuteMultipleSettings()
{
ContinueOnError = false,
ReturnResponses = true
},
// Create an empty organization request collection.
Requests = new OrganizationRequestCollection()
};
// Add a UpdateRequest for each entity to the request collection.
foreach (var entity in input.Entities)
{
UpdateRequest updateRequest = new UpdateRequest { Target = entity };
requestWithResults.Requests.Add(updateRequest);
}
// Execute all the requests in the request collection using a single web method call.
ExecuteMultipleResponse responseWithResults =
(ExecuteMultipleResponse)_serviceProxy.Execute(requestWithResults);
Few solutions comes to mind but I don't think they will please you...
Is this really a problem ? Yes it's slow and database update can be so much faster. However if you can have it as a background process (asynchronous), you'll have your numbers anyway. Is it really a "I need this numbers in the next second as soon as I click or business will go down" situation ?
It can be a reason to ditch 2013. In CRM 2015 you can use a calculated field. If you need this numbers only to show up in forms (eg. you don't use them in reporting), you could also do it in javascript.
Warning this is for the desesperate call. If you really need your update to be synchronous, immediate, you can't use calculated fields, you really know what your doing etc... Why not do it directly in the database? I know this is a very bad advice. There are a lot of reason not to do it this way (you can read a few here). It's unsupported and if you do something wrong it could go really bad. But if your real situation is as simple as your example (just a calculated field, no entity creation, no relation modification), you could do it this way. You'll have to consider many things: you won't have any audit on the fields, no security, caching issues, no modified by, etc. Actually I pretty much advise against this solution.
1 - Put it this logic to async workflow.
OR
2 - Don't use
serviceContext.UpdateObject(entA);
serviceContext.SaveChanges();.
Get all the records (150) from post stage update the fields and ExecuteMultipleRequest to update crm records in one time.
Don't send update request for each and every record
Here is a very basic example of what I want to do. The code I have come up with seems quite verbose... ie looping through the collection, etc.
I am using a Telerik MVC grid that posts back a collection of deleted, inserted and updated ViewModels. The view models are similar but not exactly the same as the entity.
For example... I have:
Order.Lines. Lines is an entity collection (navigation property) containing OrderDetail records. In the update action of my controller using the I have a List names DeletedLines pulled from the POST data. I also have queried the database and have the Order entity including the Lines collection.
Now I basically want to tell it to delete all the OrderDetails in the Lines EntityCollection.
The way I have done it is something like:
foreach (var line in DeletedLines) {
db.DeleteObject(Order.Lines.Where(l => l.Key == line.Key).SingleOrDefault())
}
I was hoping there was a way that I could use .Interset() to get a collection of entities to delete and pass that to DeleteObject.. however, DeleteObject seems to only accept a single entity rather than a collection.
Perhaps the above is good enough.. but it seemed like there should be an easier method.
Thanks,
BOb
Are the items in DeletedLines attached to the context? If so, what about this?
foreach (var line in DeletedLines) db.DeleteObject(line);
Response to comment #1
Ok, I see now. You can make your code a bit shorter, but not much:
foreach (var line in DeletedLines) {
db.DeleteObject(Order.Lines.SingleOrDefault(l => l.Key == line.Key))
}
I'm not sure if DeleteObject will throw an exception when you pass it null. If it does, you may be even better off using Single, as long as you're sure the item is in there:
foreach (var line in DeletedLines) {
db.DeleteObject(Order.Lines.Single(l => l.Key == line.Key))
}
If you don't want to re-query the database and either already have the mapping table PK values (or can include them in the client call), you could use one of Alex James's tips for deleting without first retrieving:
http://blogs.msdn.com/b/alexj/archive/2009/03/27/tip-9-deleting-an-object-without-retrieving-it.aspx