I'm trying to use the CodeFirst data migrations in EF5 with a table that has a composite natural key. Is it possible to specify this in the first argument to DbSet.AddOrUpdate, like
context.Table1.AddOrUpdate(
t=>t.Column1 && t.Column2,
new Table1 { properties... }
);
How would one specify using more than one property in this case?
Thanks,
Matthew
Turns out I had to use an anonymous type in the first argument, e.g.
t => new { t.Column1, t.Column2 }
Related
I have a postgres table in which I have some "defaulted" fields like date_created which automatically receives a current_timestamp as default.
or the ID field which gets it's value from a sequence defined in the database.
What would be (if possible) the syntax to tell the ORM module to not include these two fields when generating an INSERT statement ?
You can use a function as 2nd parameter to remove the fields:
$this->copyfrom('POST',function($val) {
unset($val['ID']);
unset($val['date_created']);
return $val
});
or to only copy allowed fields from the POST array:
$this->copyfrom('POST',function($val) {
return array_intersect_key($val, array_flip(array('name','age')));
});
Assuming you are using an HTML form to add new records into the tables, follow the steps below;
In the form, omit these 'defaulted' fields, i.e. add only the fields that you want to submit
Create a model with a function similar to below
public function add() {
$this->copyFrom ( 'POST' );
$this->save ();
}
Create a route that links the form to this function
Im trying to select only specific attributes on the many-to-many relation users, just like in one-to-one. But using select() on belongsToMany() seem to be ignored and i'm still getting all the User attributes.
class Computer extends Eloquent {
public function users() {
return $this->belongsToMany("User")->select("email");
}
public function admin() {
return $this->hasOne("User")->select("email");
}
}
Computer::with("users")->get();
Is there a way of filtering only specified columns from related entity with belongsToMany()?
Yes, you actually can.
Computer::with("users")->get(array('column_name1','column_name2',...));
Be careful though if you have the same column name for both tables linked by your pivot table. In this case, you need to specify the table name in dot notation, tableName.columnName. For example if both users and computer has a column name id, you need to do :
Computer::with("users")->get(array('users.id','column_name2',...));
According to Taylor Otwell it is not currently possible: https://github.com/laravel/laravel/issues/2679
I have tried to use a lists('user.email') at the end of the query but I can't make it work.
Computer::with(["users" => function($query){
$query->select('column1','column2','...');
}])->get();
In my application users can define Parameters, and then create SlideSets based on a grouping of parameters.
I am using code-first Entity Framework 5.0 and I have the following model:
class SlideSet {
public ICollection<Parameter> Parameter
}
class Parameter {}
A parameter might be used by many slidesets or none at all. However, in my domain a parameter has no need to reference a SlideSet, they are in separate bounded contexts (both SlideSet and Parameter are Aggregate Roots). As such, I don't want to put a reference from Parameter to SlideSet.
The table model (I don't care about table/column names) that I want is
Table SlideSet
Table Param
Table SlideSetParam
FK_SlideSet
FK_Param
I know I could model this by introducing a ParameterGroup entity or a Param.SlideSets collection, but it would exist solely for ORM mapping purposes (and cause serialization issues). Is there any other way to tell EF to generate this table model from my entities?
This should make you a Parameter w/o a navigation property:
modelBuilder.Entity<SlideSet>()
.HasMany(x => x.Parameters)
.WithRequired();
EDIT:
Based on the comment - that should be all together similar. This seems to work nicely what you're trying to do....
modelBuilder.Entity<SlideSet>()
.HasMany(x => x.Parameters)
.WithMany();
...and you can use it either way:
var slideset = new SlideSet { Parameters = new []
{
new Parameter{},
new Parameter{},
new Parameter{},
new Parameter{},
}
};
var slideset2 = new SlideSet { };
db.SlideSets.Add(slideset);
db.SaveChanges();
var slidesets = db.SlideSets.ToList();
var parameters = db.Parameters.ToList();
Console.WriteLine("");
db.SlideSets.Add(slideset2);
db.SaveChanges();
slidesets = db.SlideSets.ToList();
parameters = db.Parameters.ToList();
Console.WriteLine("");
...and the SQL:
CREATE TABLE [dbo].[Parameters] (
[ParameterID] [int] NOT NULL IDENTITY,
CONSTRAINT [PK_dbo.Parameters] PRIMARY KEY ([ParameterID])
)
CREATE TABLE [dbo].[SlideSets] (
[SlideSetID] [int] NOT NULL IDENTITY,
CONSTRAINT [PK_dbo.SlideSets] PRIMARY KEY ([SlideSetID])
)
CREATE TABLE [dbo].[SlideSetParameters] (
[SlideSet_SlideSetID] [int] NOT NULL,
[Parameter_ParameterID] [int] NOT NULL,
CONSTRAINT [PK_dbo.SlideSetParameters] PRIMARY KEY ([SlideSet_SlideSetID], [Parameter_ParameterID])
)
CREATE INDEX [IX_SlideSet_SlideSetID] ON [dbo].[SlideSetParameters]([SlideSet_SlideSetID])
CREATE INDEX [IX_Parameter_ParameterID] ON [dbo].[SlideSetParameters]([Parameter_ParameterID])
ALTER TABLE [dbo].[SlideSetParameters] ADD CONSTRAINT [FK_dbo.SlideSetParameters_dbo.SlideSets_SlideSet_SlideSetID] FOREIGN KEY ([SlideSet_SlideSetID]) REFERENCES [dbo].[SlideSets] ([SlideSetID]) ON DELETE CASCADE
ALTER TABLE [dbo].[SlideSetParameters] ADD CONSTRAINT [FK_dbo.SlideSetParameters_dbo.Parameters_Parameter_ParameterID] FOREIGN KEY ([Parameter_ParameterID]) REFERENCES [dbo].[Parameters] ([ParameterID]) ON DELETE CASCADE
...this makes the original tables practically 'agnostic' of the relationships (many-to-many) - while index table is automatically generated in the background.
You can also further customize that and make your own SlideSetParam (e.g. if you'd want to add additional fields there) with pretty much the same layout - just Parameters would have to point to that instead.
I have 2 Entities, each of which is managed by EF Code First, and each happily sitting in its own table. Entity_A has a property, called "SumTotal", which should be the sum of a specific column in Entity_B that matches a certain criteria.
SumTotal should not be persisted in the DB, but rather calculated each time an instance of Entity_A is retrieved.
I have looked at ComputedColumns, but it appears that the computedcolumn can only be defined relative to columns in the same table.
I also have a feeling that I need to set SumTotal to NotMapped (or something similar with AutoGenerated), but dont know how to get the actual value into SumTotal.
Hope this question makes sense, thanks in advance
You can project the results to an anonymous object and transform that it to your entity
var projection = db.EntityAs.Where(/* */)
.Select(a => new {A = a, Sum = a.Bs.Sum(b => b.Total)})
foreach(p in projection)
{
p.A.SumTotal = p.Sum;
}
var As = projection.Select(p => p.A);
I implemented inheritance with a discriminator field so all my records are in the same table. My basetype is Person (also the name of the table) and Driver and Passenger inherit from it. I receive instances of the correct type (Driver and Passenger) when I perform a query on the object context to Person. example:
var q = from d in ctx.Person
select d;
But I also create a function that calls a stored procedure and mapped the output of the function to the type Person. But now I get a list of Person and not Drivers or Passengers when I execute this method.
Anybody an idea how to solve this or is this a bug in EF4?
AFAIK, you can't use discriminator mapping (e.g TPH) when dealing with stored procedure mappings.
The stored procedure must be mapped to a complex type or custom entity (e.g POCO), the mapping cannot be conditional.
What you could do is map it to a regular POCO, but then project that result set into the relevant derived type (manual discrimination).
E.g:
public ICollection<Person> GetPeople()
{
var results = ExecuteFunction<Person>(); // result is ObjectResult<Person>
ICollection<Person> people = new List<Person>();
foreach (var result in results)
{
if (result.FieldWhichIsYourDiscriminator == discriminatorForDriver)
{
people.Add((Driver)result);
}
// other discriminators
}
}
If your always expecting a collection of one type (e.g only Drivers), then you wouldn't need the foreach loop, you could just add the range. The above is in case you are expecting a mixed bag of different people types.
Would be interested to see other answers, and if there is a better way though - but the above should work.