This question already has an answer here:
EF 6, code first junction table name
(1 answer)
Closed 2 years ago.
I set up a database using EF 6. I configured a many-to-many relationship successfully with the code seen below:
public class Software
{
public string Id { get; set; }
public string Version { get; set; }
public string Name { get; set; }
// Navigation property for machineSoftware
public virtual ICollection<Machine> MachineSoftwares { get; set; }
}
public class Machine
{
public int MachineId { get; set; }
public string Model { get; set; }
public string Customer { get; set; }
public virtual ICollection<Software> MachineSoftwares { get; set; }
}
EF 6 created a third table MachineSoftwares automatically. So far so good.
Now I want to rename that table, but I don't have a corresponding class for that table that I could rename via migration. So how can I rename the table MachineSoftwares?
The name of the implicit many-to-many junction table (and the names of its columns) are configured through the Map Fluent API.
But in order to get access to that API, you have to first map the relationship using a HasMany / WithMany pair:
modelBuilder.Entity<Software>()
.HasMany(e => e.MachineSoftwares)
.WithMany(e => e.MachineSoftwares)
.Map(config => config
.ToTable("the_desired_table_name")
//.MapLeftKey("SoftwareId") // in case you need different column names
//.MapRightKey("MachineId")
);
you can add Table attribute to your code, EF have more options for attributes, for example the name of column:
[Table("custom_name_table")]
public class Software
{
public string Id { get; set; }
[Column("the_version_name")]
public string Version { get; set; }
public string Name { get; set; }
// Navigation property for machineSoftware
public virtual ICollection<Machine> MachineSoftwares { get; set; }
}
check this link https://www.entityframeworktutorial.net/code-first/table-dataannotations-attribute-in-code-first.aspx
Related
This question already has answers here:
Prevent Adding New Record on Related Table Entity in Entity Framework
(1 answer)
Entity Framework Core insert record into database
(2 answers)
Closed 3 months ago.
I set up a database with ef core code first management. I have two related tables.I want to insert data into a table. but since it has a relationship with the other table, it tries to throw data into the other table. whereas I only want to record a table. how do i do this?
code:
table
public class JobTable
{
[Key]
public int ID_JOB { get; set; }
public JobType JobType { get; set; }
public string JOB_KEY { get; set; }
public TimeSpan JOB_TIME { get; set; }
public int? DAY { get; set; }
public Boolean IS_ACTIVE { get; set; }
public string? DESCRIPTION { get; set; }
public CustomUser CustomUser { get; set; }
}
table:
public class JobType
{
[Key]
public int ID_JOB_TYPE { get; set; }
public string JOB_TYPE_NAME { get; set; }
public List<JobTable> jobTable { get; set; }
}
ef code:
context.JobTable.Add(jobTable);
context.SaveChanges();
i just want to add data to 'jobtable' table. but it tries to throw data into the 'jobtype' table as well, since it is related to the 'jobtype' table. idont want this. how can I do it?
The current way that you define the JobTable will also create a new record for JobType when inserting the JobTable record.
Instead, modify the JobTable to apply a foreign key property (JobTypeId) to define a relationship to the JobType table.
public class JobTable
{
...
public int JobTypeId { get; set; }
public virtual JobType JobType { get; set; }
}
public class JobType
{
...
public ICollection<JobTable> JobTables { get; set; }
}
During inserting the new JobTable record, you need to provide the JobType's Id into the entity data to be inserted.
Reference
One-to-Many Relationship Conventions in Entity Framework Core (Convention 4)
This question already has answers here:
Entity Framework Core - Multiple one-to-many relationships between two entities
(2 answers)
Closed 2 years ago.
I started using EF Core with the database-first approach, I had two tables CalendarDates and Deals. A deal has multiple date-related properties for which separate foreign key relationships have been been set-up. In the below example StartDate and EndDate.
The scaffolded DbContext showed the class definitions as such:
public class CalendarDate
{
public CalendarDate()
{
DealsStartedOnThatDate = new HashSet<Deal>();
DealsEndedOnThatDate = new HashSet<Deal>();
}
[Key]
public string Id { get; set; } = string.Empty;
public DateTimeOffset Date { get; set; }
public int Year { get; set; }
public virtual ICollection<Deal> DealsStartedOnThatDate { get; set; }
public virtual ICollection<Deal> DealsEndedOnThatDate { get; set; }
}
public class Deal
{
[Key]
public string Id { get; set; } = string.Empty;
public string Name { get; set; } = string.Empty;
public string StartDateId { get; set; } = string.Empty;
public virtual CalendarDate StartDate { get; set; } = null!;
public string EndDateId { get; set; } = string.Empty;
public virtual CalendarDate EndDate { get; set; } = null!;
}
I now want to make the move to code-first. But when I add the migration the following error is thrown:
Unable to determine the relationship represented by navigation property 'CalendarDate.DealsStartedOnThatDate' of type 'ICollection<Deal>'. Either manually configure the relationship, or ignore this property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.
If I comment-out the fields belonging to EndDate in both classes, it works just fine. So it seems that I cannot use more than one MANY:ONE relationship (many=Deals,one=CalendarDates) here. Althoug it worked just fine when scaffolded from an existing database with existing FK constraints.
What am I missing here?
Cheers
Please try configuring relationships in the OnModelCreating like this
modelBuilder.Entity<Deal>().HasOne(cd => cd.StartDate)
.WithMany(c => c.DealsStartedOnThatDate).HasForeignKey(d => d.StartDateId);
modelBuilder.Entity<Deal>().HasOne(cd => cd.EndDate)
.WithMany(c => c.DealsEndedOnThatDate).HasForeignKey(d => d.EndDateId);
Edit : checked&fixed
Based on the solution provided in this question : How to update foreign key in EF 6 - Code First, I'm able to update my foreign key using the id field.
But now, I get an exception when getting entities from the database. Using this code :
// Retrieve data first
using (var db = new TestDbContext())
{
var p2 = db.Persons.First();
}
I get the following SqlException : "Invalid column name 'Country_Id1'."
Does anyone have any clues to be able to retrieve data and to update the foreign key ?
Asked in another way, is it possible to use both the navigation property to ease the use of my entity and the id of the foreign key to be able to update my dependent entity ?
My entities
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
public virtual Country Country { get; set; }
public int Country_Id { get; set; }
}
public class Country
{
public int Id { get; set; }
public string Name { get; set; }
}
That might be because entity framework is trying to create new foreign key based on navigation property Country in Person entity.
I think you should annotate Country_Id property with ForeignKey attribute as below.
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
[ForeignKey("Country_Id")]
public virtual Country Country { get; set; }
public int Country_Id { get; set; }
}
However if you follow the ef naming convention for naming property as below, you don't need to annotate it.
Any property with the same data type as the principal primary key
property and with a name that follows one of the following formats
represents a foreign key for the relationship: '', '', or ''
You may read more from here
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
public virtual Country Country { get; set; }
public int CountryId { get; set; }
}
Note: you might need to run database migration or need to recreate database.
My problem looks simple. I need to implement a relationships between items in the database. For example: relationship between entities like computer and software shows users that computer stores a specific software and similarly - a software is installed in the specific computer. I think I should implement an entity with source id and target id or something similar. I wrote some code using code first in EntityFramework 6. Here are two classes:
public class ConfigurationItem
{
public int Id { get; set; }
public String Name { get; set; }
public String DeploymentState { get; set; }
public String IncidentState { get; set; }
[DataType(DataType.MultilineText)]
public String Description { get; set; }
[DataType(DataType.MultilineText)]
public String Note { get; set; }
public virtual ICollection<Relationship> Relationship { get; set; }
}
public class Relationship
{
[Key]
public int RelationshipId { get; set; }
[ForeignKey("ConfigurationItem")]
public int SourceId { get; set; }
[ForeignKey("ConfigurationItem")]
public int TargetId { get; set; }
public String Type { get; set; }
public virtual ConfigurationItem Source { get; set; }
public virtual ConfigurationItem Target { get; set; }
}
This solution doesn't work. I need a tip or something what should I try to make it work properly. EF throws an error about foreign key:
The ForeignKeyAttribute on property 'SourceId' on type 'cms_1.Models.Relationship' is not valid. The navigation property 'ConfigurationItem' was not found on the dependent type 'cms_1.Models.Relationship'. The Name value should be a valid navigation property name.
When I try to resolve it EF throws an error about cascade deleting. I know how to disable it but I just don't want to. I need a proper solution with that feature but I think I don't know how to do a model representing given scenario.
Simply - I need to store two foreign keys from entity "A" in the entity "B". How is it possible?
from a quick review , I can tell that you need 3 tables :
first : Computer
second : Software
third : a table , lets call it ComputerSoftware which tell which software has in what computer ( or you can also see it - which computer use what software ), which has ComputerID column and SoftwareID column.
example (source)
class Country
{
public int Id { get; set; }
public virtual ICollection<CountryCurrency> CountryCurrencies { get; set; }
}
class Currency
{
public int Id { get; set; }
}
class CountryCurrency
{
[Key, Column(Order=0)]
public virtual int CountryId { get; set; }
[Key, Column(Order=1)]
public virtual int CurrencyId { get; set; }
public virtual Country Country { get; set; }
public virtual Currency Currency { get; set; }
}
Your issue could be that in the migration file creating those tables, it will have something like
.ForeignKey("dbo.Relationship", t => t.Id, cascadeDelete: true)
This will be set on both tables, ConfigurationItem and Relationship of their Primary Key fields. When you delete one, that config tells SQL Server to delete the relationships as well and the relationship probably has a cascadeDelete: true to the parent. This will cause the cyclical cascading delete issue you are experiencing.
After the migration has been generated, go in and change one or all to cascadeDelete: false and this will fix that issue. This is what EF generates by default if I recall.
I need help creating the relationship in entity framework as everything I have tried gives me errors when trying to add the migration or if I get passed that then I try to update the database and get an error about indexes with the same name.
public class Profile
{
public Profile()
{
Environments = new HashSet<Environment>();
}
[Key]
public int Id { get; set; }
public string VersionCreated { get; set; }
public string DiskLocation { get; set; }
public string Name { get; set; }
public DateTime DateTime { get; set; }
public virtual Product Product { get; set; }
public virtual Instance OriginalInstance { get; set; }
public virtual ICollection<Environment> Environments { get; set; }
}
public class Instance
{
public Instance()
{
TestResults = new HashSet<TestResult>();
Environments = new HashSet<Environment>();
}
[Key]
public int Id { get; set; }
public string Name { get; set; }
public string Version { get; set; }
public string UserFriendlyName { get; set; }
public virtual Product Product { get; set; }
public virtual Profile LastKnownProfile { get; set; }
public virtual Computer Computer { get; set; }
public virtual ICollection<TestResult> TestResults { get; set; }
public virtual ICollection<Environment> Environments { get; set; }
}
The problem with the above classes is that the OrginalInstance property on the Profile class and the LastKnownProfile in the Instance class are supposed to just be foreign keys to those specific tables and they probably won't be the same very often. They can also both possibly be null.
I have tried:
modelBuilder.Entity<Instance>().HasRequired(i => i.LastKnownProfile);
modelBuilder.Entity<Profile>().HasRequired(p => p.OriginalInstance);
This gave me an Unable to determine the principal end of an association between the types 'EcuWeb.Data.Entities.Instance' and 'EcuWeb.Data.Entities.Profile'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations. error.
and with:
modelBuilder.Entity<Instance>().HasRequired(i => i.LastKnownProfile).WithOptional();
modelBuilder.Entity<Profile>().HasRequired(p => p.OriginalInstance).WithOptional();
The database adds a foreign key reference back to itself.
...that the OrginalInstance property on the Profile class and the
LastKnownProfile in the Instance class are supposed to just be foreign
keys to those specific tables and they probably won't be the same very
often. They can also both possibly be null.
In this case you actually want two one-to-many relationships between Profile and Instance if I don't misunderstand your quote above. It would mean that many Profiles can have the same OriginalInstance and that many Instances can have the same LastKnownProfile. The correct mapping would look like this then:
modelBuilder.Entity<Profile>()
.HasOptional(p => p.OriginalInstance)
.WithMany()
.Map(m => m.MapKey("OriginalInstanceId"));
modelBuilder.Entity<Instance>()
.HasOptional(i => i.LastKnownProfile)
.WithMany()
.Map(m => m.MapKey("LastKnownProfileId"));
The lines with MapKey are optional. Without them EF will create a foreign key with a default name.
Also note that you must use HasOptional (instead of HasRequired) if "both can possibly be null".