I have two tables have circular reference to each other (you can see the FK and PK i nthe image)
(In otherprotectionItems table , I have a column from Document , and that record in document is related to otherprotectionItem table ad a foreign key. the first relation is NO ACTION in delete and the second relation is CASCADE on delete)
I have this issue when I want to delete a row in otherprotectionItem table.
Error :
Unable to determine a valid ordering for dependent operations. Dependencies may exist due to foreign key constraints, model requirements, or store-generated values.
Just wanto to note , I have this solution. but I prefer to have a better . Otherwise this is the answer.
I will remove the documents manually , save change in DB . and then remove the OtherprotectionItem table record
Data.Util.DocumentFinder.FindRecursive(item)
.ToList()
.ForEach(d => db.Entry(d).State = System.Data.Entity.EntityState.Deleted);
db.SaveChanges();
db.OtherProtectionItems.Remove(item);
db.SaveChanges();
Note : this FindRecursive is a function I create and it iterates all documents and find all documents related to this OtherprotectionItem record
Related
My database looks like this: Database Diagram MSSMS
So everytime i'm adding a fish to the database, i want to add the fishes's continent, waterlagen and verbanden.
Tables Continenten, Waterlagen & Verbanden are already filled with objects from an array after creating the database.
Im using List Continenten; for example to store multiple continents.
So i tryed:
Vis nieuweVis = new Fish();
nieuweVis.Naam = "Molly";
foreach(Continent c in Continenten)
nieuweVis.Continenten.Add(c)
so in the table VisContinenten
i assume that EF will automaticly fill in the FishId and ContinentId wich are foreignkeys.
I want records in that table also to be unique so i add a unique key to both the columns in VisContinenten so that fish 1 on continent 1 won't appear twice in that table.
Error i get:
An error occurred while saving entities that do not expose foreign key
properties for their relationships
Additional information: Unable to update the EntitySet 'VisContinenten' because it has a DefiningQuery and no element exists in the element to support the current operation.
Help me pls :)
Thank you
I have a database with three tables: Word, Idiom, WordIdiom that stores many to many relation between this two tables. WordItem includes only foreign keys for Word and Idiom tables.
After that, I have created Entity model, based on database. I have filled two tables with relevant content, and now I want to add cross-links between these tables.
So, I have written this code:
using (var db = new IdiomsDictionaryEntities())
{
var allIdioms = from idiom in db.Idioms select idiom;
foreach (var idiom in allIdioms)
{
string[] words = idiom.IdiomText.Split(new[] { " ", "-" }, StringSplitOptions.None);
foreach (var word in words)
{
var wordItem = db.Words.SingleOrDefault(exWord => exWord.WordString.ToLower().Equals(word));
if (wordItem == null)
{
Console.WriteLine("Idiom: " + idiom.IdiomText + ", missing word: " + word);
continue;
}
idiom.Words.Add(wordItem);
db.SaveChanges();
}
}
}
But when I run this code, I'm getting following error:
An unhandled exception of type 'System.Data.Entity.Infrastructure.DbUpdateException' occurred in EntityFramework.dll
Additional information: An error occurred while saving entities that do not expose foreign key properties for their relationships. The EntityEntries property will return null because a single entity cannot be identified as the source of the exception. Handling of exceptions while saving can be made easier by exposing foreign key properties in your entity types. See the InnerException for details.
Inner-inner exception:
Unable to update the EntitySet 'WordIdiomMatch' because it has a DefiningQuery and no element exists in the element to support the current operation.`
As it is my first time with Entity Framework, I'm really don't know how to fix this. I have tried to add [ForeignKey()] property to Entity Framework models, but probably have done it wrong. I have also tried to add a primary key for WordIdiom, but it brakes even more things, as in this case I cannot even add items to Word and Idiom tables.
I have solved the problems, with help of #KerryRandolph and #AntoinePelletier
I was trying to update entities derived from a many-to-many relationship using Pure Join Table - meaning no other columns except foreign keys are allowed.
If you add a Primary Key column to a Join Table, you lose all of the entity framework advantages and have to implement insertion operation manually.
Proper solution was to alter the join table on the DB to make a PK that includes BOTH of the foreign ID columns.
First of all, i see that you have 2 add() for the same purpose. Witch is wrong. Imagine what it would look like in the data base :
wordItem.Idioms.Add(idiom);
ok now X and Y are linked by the link table as "X-Y" record.
idiom.Words.Add(wordItem);
And now... it would create another record that link these as "Y-X" witch is useles, if there is already an "X-Y" record then X is linked to Y with this single record and the other way around too.
And i'd say... usualy the primary key of a link table is the combination of the two foreign keys it contain, so the double add would crash anyway.
I have removed the PrimaryKey from my table, refreshed the EDMX, and now I am getting this error message when doing db.SaveChanges():
Unable to update the EntitySet 'Results' because it has a DefiningQuery and no element exists in the element to support the current operation.
Now...
1 - I dont want PrimaryKey in my table. The table is just a bag of values, no PK is required.
2 - I read another post where someone suggested to remove DefiningQuery element from EF generated EDMX. It is not working, and I avoid manual changes to automatically generated EDMX.
Any idea how I can avoid this error, and not define PK in my table?
Thanks.
In Entity Framework everything must have a key, at least in the model. You can remove it from the database but still you'll have to define a key in the model, which may be a composite key to ensure it is unique. Otherwise EF won't be able to materialize or save objects correctly.
However, I would use a primary key in the table anyway. It is no trouble at all to have an identity field in it and you don't have to worry about finding a unique combination of fields yourself. I can't imagine that the table does not need some notion of identity, or can it really have two exactly identical rows?
Let's say I have a Database with 3 tables: Keywords, Documents, and KeywordDocuments. KeywordDocuments has only 3 columns, KeywordDocumentID, KeywordID, and DocumentID.
The relationship between Documents and KeywordDocuments is the same as Keywords and KeywordDocuments, i.e. one-to-many.
Watching Julie Lerman's video on EF, she said that we don't need KeywordDocuments's entity in the model. How do I eliminate that entity while making sure that in the relationship will be respected in the underline database?
Thanks for helping
Remove the KeywordDocumentID column from the KeywordDocument table. It will then contain only the foreign key columns from the tables for which it represents a many to many relationship.
Create a new composite primary key on the KeywordDocument table which includes both the KeywordID and the DocumentID columns. This will replace the original primary key that you had on the KeywordDocumentID column - that key would have been deleted along with the column.
A table such as this will not result in an entity being generated in the model. Rather, both of the other entities (Keyword and Document in this case) will have navigation properties based on EntityCollection. Document will have a collection of Keywords and vice verca.
I have 3 normalised tables consisting of Employees, Departments and EmployeesToDepartments. I wish to be able to assign an Employee to one or more Department, hence the link table (EmployeesToDepartments). I can successfully query the database and extract the full hierarchy of entities via the Navigation properties using
this.ObjectContext.Employees.Include("EmployeesToDepartments").Include("EmployeesToDepartments.Department")
plus the [Include] attribute in the metadata, thus allowing me to access the Departments for a given Employee. Upon trying to remove a link between an [Employee] and [Department] in the [EmployeesToDepartments] table I was given a Foreign Key Constrain error.
I have simplified my model to include just one navigation property between [Employees] and [EmployeesToDepartments]. A Foreign Key constraint between[Employees].[ID] and [EmployeesToDepartments].[IDEmployee] was preventing me from updating the EmployeesToDepartments table. With this removed via a Relationship setting I can now update the table. I can now execute the following code
foreach (var rel in _employee.EmployeesToDepartments)
{
_employee.EmployeesToDepartments.Remove(rel);
}
_domainContext.SubmitChanges();
without error.
I was expecting to see the entries in the RelEmployeesToDepartments with the IDEmployee to have been deleted. What I see in the table are the value 0 where the IDEmployee previously was.
Is it possible to force a DELETE statement to be issued? Am I misunderstanding the basic concepts here?
Any help would be much appreciated.
Removing entities in navigation property only breaks the link between entities. You have to delete from the EntitySet to achive what you want.
ex)
myDomainContext.EmployeeDepartments.Remove(employeeDepartmentToRemove);
myDomainContext.SubmitChanges();