I'm using the Propel ORM. One of my tables is called "friend" and its entries represent many-to-many-relationships. The table "friend" has to entries:
profile_id
friend_profile_id
These two properties obviously create the PrimaryKey.
Now I would like to update this table, with new Information. So I would like to save new Friend-Entries like so:
$friendCon = new RplFriend();
$friendCon->setProfileId($profile->getId());
$friendCon->setFriendProfileId($friendProfile->getId());
$friendCon->save();
But at this point, I dont know if such an entry already exists. So I get lots of "Duplicate Entry" errors from Propel. What is the most performant way, to only save a new entry, if it doesnt already exist?
Maybe you should try something like:
$friendCon_duplicate = RplFriendQuery::create()->findPK($profile->getId(),$friendProfile->getId());
if($friendCon_duplicate..
set unique index of those 2 fields in your database
Related
I have accidentally created hundreds of columns in my User class. Can anyone tell me how to easily delete a number of columns? Currently the only way I can delete them is individually through the Parse online interface.
You can use the Schema API to delete columns from your collection, check the documentation for details. A good strategy might be to fetch a list of columns the collection you want to modify has, create a list of columns you want to keep and then delete each column that is not in this list.
Ok, so I have 2 entities: Course and Industry
The industry entity is just a reference table which lists all available Industries that can be tagged to a course, to categorizing them. I put in a many to zero or one relationship (a course can choose to have an industry or not, while an industry can be tagged with many courses).
I know I've played around with the diagrams a bit, adding and removing associations in the past.
Now here is the odd part: The column mappings for Course has 2 similar columns, IndustryId and Industry_Id
I suspect it's from a past association, but thought EF would have taken care of that.
Here is the problem:
In my view that creates the course, the IndustryId is the property which needs to be populated. When I create new courses, I see the IndustryId in the database populated.
However, when I access Industry's properties through Course (Course.Industry.Description) nothing is populated. It can't seem to get the Industry entity.
I see the IndustryId populated in the db, so I tried to populate the Industry_Id column. That fixed it.
Weird enough, the property declared in the model is IndustryId, so that column is populated in the db. But when I try to get Industry entities through Course, it needs the Industry_Id, which I don't quite know where it is from.
Anyone have any ideas?
It sounds like in your updating from the database, you changed the column name on your tables from Industry_Id to IndustryId. The next time you updated from the database, EF5 (which can't determine that this is the same column, as it matches on names) dropped the mapping for Industry_Id, and added a new column called IndustryId.
However, you had already created the foreign-key mapping in your EDMX file based on the Industry_Id column - which is why you get the issue around needing it when loading related records.
In general, when using Database-First, whenever you rename a column in the database, you need to update your EF5 model and update / correct any such discrepancies.
I am using Database First EF to generate model from the existing database. When I first generated the models, it ignores only one of the table, the entity was not added to EDMX, no model file is created for the table and no context is created for the entity.
When I tried to explicitly add the table to EDMX (when generating the model, selected the specific table first and then updated the model with all the other tables from the database), it complained with the following error.
Two entities with possibly different keys are mapped to the same row. Ensure these two mapping fragments map both ends of the AssociationSet to the corresponding columns.
This specific table has two columns which are primary keys of some other tables and both the columns are specified as Primary keys for the table.
Am I doing something wrong or should I handle this table differently since it has two columns defined as Primary Keys? Any suggestions greatly appreciated!
You are not doing anything wrong. Your table is junction table for many-to-many relation. You don't need that table in the model because EF (in contrast to database) can handle many-to-many relation directly without any intermediate. The table is actually mapped on behind of the many-to-many relation - you will see that in mapping details window.
Btw. you are not using code first. Code first = no EDMX.
I am somewhat new to LINQ and have a quick question regarding deleting.
Say, for example I have 2 tables, Orders and OrderItems. Using LINQ, I can easily create a new child record by using
order.Items.Add(new OrderItem());
and this will create the child record in the database and update its foreign key to the orderId. This is great, I like it! However when I want to remove a child record
order.Items.Remove(orderItem);
I get an error when I sumbit the changes (because its not actually deleting the child row (order item), just removing the foreign keyId). Is it possible to do this the way I would like to? I don't want to have to create a whole bunch of repositories and if ladders to delete all child rows for a large database.
Thanks in advance.
E
You can achieve that in the DB itself by configuring the Foreign key relationship to delete child records on deletion of the parent's key.
Note that this is transparent to Linq2SQL and it will not be aware of it, so it's best to make sure you do not keep the datacontexts around after that, since the OrderItem objects will still be present.
Set ON DELETE CASCADE for the table in question which will let the SQL Server handle this for you.
I am working with a few legacy tables that have relationships, but those relationships haven't been explicitly set as primary/foreign keys. I created a .dbml file using "Linq To Sql Classes" and established the proper Case.CaseID = CaseInfo.CaseID association. My resulting class is CasesDataContext.
My Tables (One to many):
Case
------------------
CaseID (int not null)
MetaColumn1 (varchar)
MetaColumn2 (varchar)
MetaColumn3 (varchar)
...
CaseInfo
------------------
CaseInfoID (int)
CaseID (int nulls allowed)
CaseInfoMeta (varchar)
...
I'm new to LinqToSQL and am having trouble doing..
CasesDataContext db = new CasesDataContext();
var Cases = from c in db.Cases
where c.CaseInfo.CaseInfoMeta == "some value"
select c;
(Edit) My problem being that CaseInfo or CaseInfos
is not available as a member of Cases.
I heard from a colleague that I might try ADO.Net Entity Data Model to create my Data Context class, but haven't tried that yet and wanted to see if I'd be wasting my time or should I go another route. Any tips, links, help would be most appreciated.
Go back to the designer and check the relation is set up correctly. Here is one real life example, with BillStateMasters have "CustomerMasters1" property (customers for the state):
Ps. naming is being cleaned up ...
Update 1: You also need to make sure both tables have a primary defined. If the primary key isn't defined on the database (and can't be defined for whatever reason), make sure to define them in the designer. Open the column's properties, and set it as primary key. That said, entity tracking also won't work if you haven't a primary key for the entity, which for deletes means it silently doesn't updates the entity. So, make sure to review all entities and to have them all with a primary key (as I said, if it can't be on the db, then on the designer).
CasesDataContext db = new CasesDataContext();
var Cases = from c in db.Cases
join ci in db.CaseInfo on
ci.ID equals c.InfoID
where ci.CaseInfoMeta == "some value"
select new {CASE=c, INFO=ci};
my "join" linq is a bit rusty, but the above should get close to what you're after.
Is the association set to One to One or One to Many? If you have the association set to One to Many, then what you have is an EntitySet, not an EntityRef and you'll need to use a where clause on the dependent set to get the correct value. I suspect that you want a One to One relationship, which is not the default. Try changing it to One to One and see if you can construct the query.
Note: I'm just guessing because you haven't actually told us what the "trouble" actually is.
Your query looks correct and should return a query result set of Case objects.
So... what's the problem?
(Edit) My problem being that CaseInfo
is not available under Cases... i.e.
c.CaseInfo doesn't exist where I'm
assuming it would be if there were
explicit primary/foreign key
relationships.
What do you mean by "not available"? If you created the association in the designer as you say you did, then the query should generate SQL something along the lines of
SELECT [columns]
FROM Case INNER JOIN CaseInfo
ON Case.CaseID = CaseInfo.CaseID
WHERE CaseInfo.CaseInfoMeta = 'some value'
Have you debugged your linq query to get the SQL generated yet? What does it return?
Couple of things you might want to try:
Check the properties of the association. Make sure that the Parent property was created as Public. It does this by default, but something may have changed.
Since you're not getting CaseInfo on C, try typing it the other direction to see if you get ci.Case with intellisense.
Delete and recreate the association all together.
There's something very basic going wrong if the child members are not showing up. It might be best to delete the dbml and recreate the whole thing.
If all else fails, switch to NHibernate. :)
After a few tests, I'm pretty sure the FK relationships are required in the DB regardless of whatever associations are created in Linq-to-SQL. i.e. if you don't have them explicitly set in the DB, then you will have to do a join manually.
Is this c#? I think you need == instead of = on this line:
where c.CaseInfo.CaseInfoMeta = "some value"
should read
where c.CaseInfo.CaseInfoMeta == "some value"