Im getting errors when I try to remove an entity with Dbcontext.Remove(my_entity). I am doing a search, which finds the entity in the Db and it along with others are to be removed when I call SaveChanges.
However, since my EF model on this entity says that some fields are required, and even though the entities in the Db have empty string values in these fields, I cant seem to remove them when savechanges is called, since I think the model validation is failing.
So in the model for this particular entity, I have data annotations like this
[Required]
[StringLength(20)]
public string RackCode { get; set; }
Now, in the Db, there are null values in this field for the list of entities that I am removing. How can I get EF to let me remove these?
Related
I have the following Entity:
public class Invoice
{
[Key]
public int Id { get; set; }
public DateTime? ArchiveDate { get; set; }
public DateTime? ClotureDate { get; set; }
...
}
I would like to know whether my invoice is archived or closed by using a kind of flag (boolean). For that purpose I added 2 unmapped properties in my breeze entity like this:
public class Invoice
{
[Key]
public int Id { get; set; }
public DateTime? ArchiveDate { get; set; }
public DateTime? ClotureDate { get; set; }
[NotMapped]
public bool Archived { get { return ArchiveDate.HasValue; } }
[NotMapped]
public bool Clotured { get { return ClotureDate.HasValue; } }
...
}
Now I can query my breeze entity like this:
var query = entityQuery.from("Invoices")
.where('id', '==', id)
.toType('Invoice');
The call above will return all properties of my invoice entity (including archived & clotured). It works well.
But I need only a few specific properties (for performance). Then I try:
var query = entityQuery.from("Invoices")
.where('id', '==', id)
.select("id, archived, clotured")
.toType('Invoice');
I got the error: The specified type member 'Archived' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.
Very frustrating. Any idea why do I cannot perform such query?
Or maybe does someone have another solution?
Many thanks.
Short version
What you are seeing is perfectly expected. The ArchivedDate is both a persisted data property and a serialized property. The Archived property is not persisted but it is serialized. That's why you see data values for both ArchivedDate and Archived. However, your remote query ... the LINQ query executed on the server ... may only refer to the persisted properties such as ArchivedDate. EF knows nothing about calculated properties such as Archived; they cannot participate in a LINQ query ... not in a where, select, orderBy or any other query. You can't mention something in a query that EF doesn't know about ... and you told EF (properly) to ignore these Archived and Clotured calculated properties.
Long version
The [Unmapped] attribute hides the properties from EF ... as it must because Archived and Clotured are calculated properties, not persistable data.
The [Unmapped] attribute also hides these properties from the metadata generated from EF. That too is both expected and good.
But this also means that you cannot construct a LINQ query that references these properties. They aren't data properties. They can't be queried by EF. Only data properties and navigation properties can appear in a LINQ query. It is really that simple.
Perhaps you're wondering why the unmapped calculated property values are actually communicated to the JavaScript client, why those values appear in the JSON payload and would populate the like-named Breeze entity properties if you add such properties to the client metadata for Invoice as "unmapped properties".
To understand why, you must understand the difference between properties that you query with EF and the properties that you serialize with Json.NET. After the EF query completes, the materialized entities have both the data properties (e.g., ArchivedDate) and the calculated properties (Archived). The [NotMapped] attribute doesn't hide a property from Json.NET. Json.NET serializes ALL properties of the materialized object - both data and calculated properties - unless you tell it not to. For example you could hide the Archived property from Json.NET serialization with the [Ignore] attribute.
The toType is a red herring and has no bearing on the matter.
Remove the ".toType('Invoice')' line from your query. Just go with:
var query = entityQuery.from("Invoices")
.where('id', '==', id)
.select("id, archived, clotured");
This forces breeze to coerce your projection into an Invoice entity type. If you leave it off you will get a true projection, i.e. a plain javascript object with just the properties you have specified, i.e. not an entity.
I am starting an MVC project and designing my DB in EF, which means I design the tables, and VS creates the classes I need to access them.
The problem is, I want to make use of attributes like DisplayName, Required and generating validation error messages ( including specifying rules to validate ).
As far as I can see, the classes are recreated every time I change my DB, so I can't really add them to the classes. Is there another way to do this once and have it persist ?
So you would use the MetadataType attribute and link your entity to a type where you'll set the validation attributes.
Something like this for an Entity Person:
[MetadataType(typeof(Person_Validation))]//<<link to metadata class
public partial class Person//<<<Your real entity class
{//this is in a separate file.
//note =>partial. There's nothing in this class
}
public class Person_Validation//the validations go here.
{
[StringLength(255, ErrorMessage="Name is required"), Required]
[DisplayName("Name")]
public string Name { get; set; }
}
I have same type of tables
ProductCodeTable, CountrycodeTable etc
All have key, value as their fields
When I use entity frame work,
Can I have a single entity for all these tables such that I can formulate different queries to get data from different tables?
You can create a base class for all of them and create sub class for each entity
public abstract class LookUpEntity
{
[Key]
public int Key { get; set; }
[Required]
public string Value { get; set; }
}
[Table("ProductCodeTable")]
public class ProductCode : LookUpEntity
{
}
This way you can model the relationships also and later if you wanted to add specific properties to those look up entities with out affecting other entities.
You can create a view with a Union of all tables like this:
create view AllKeyTables as
SELECT 'Product' as table, Productkey as Key, nameProduct as name
FROM ProductCodeTable
UNION
SELECT 'Country' as table, CountryISO as key, CountryName as name
FROM CountrycodeTable
UNION
...
Then update EF model and check 'table' and 'key' fields as Entity Primary Key.
Next question you will do is: 'How can I make a relation between this Entity and existing Entities?' The answer is 'you can't because EF is not able to join Entities between other fields than primary key'. Then, before implement this solution, be sure that this is you are looking for.
EF supports this only if you model it as inheritance (#Eranga showed it in code-first approach). You will have single base entity and derived entity for each table so you will not avoid having different type for each table. Otherwise the answer is no.
Inheritance will put additional requirements on data in your tables. For example Ids will have to be unique among all tables. So if ProductTableCode will have record with Id 1, CountryCodeTable (and any other code table) mustn't have record with Id 1.
Also inheritance in EF can produce nasty and very poorly performing queries.
This is the basic example from hbm-style nhibernate.
http://ayende.com/blog/2327/multi-table-entities-in-nhibernate
public class Person
{
public int PersonId {get;set;}
public string Name {get;set;}
public string AddressStreetAddress {get;set;}
public string AddressZipCode {get;set;}
}
In the database, Person has an Id primary key, a name field, and an address foreign key. Address has its own primary key, a street address field and a zip code field.
The correct answer is "Don't do it.". Unfortunately I'm stuck with an entity object that exposes the Id and Name of another entity and those are used elsewhere still. At the moment, this object won't be persisted back to the database through nHibernate.
I think the way to do this is to use the address as the table of the entity and add the Person fields from the Join(). What are the consequences of doing this as an intermediate step in a change-over?
I think the way to do this is to use
the address as the table of the entity
and add the Person fields from the
Join(). What are the consequences of
doing this as an intermediate step in
a change-over?
This was a bad idea because the only Id you could map to is the Id of the address which can be shared between multiple persons.
Instead, add a private/protected property for Address to Person, map Address and reference the address using the following Fluent call.
References(Reveal.Member<Person, Address>("Address")).Column("address_id")
Then, you can use AddressStreetName and AddressZipCode to pass through to Address.StreetName and Address.Zipcode. After that, it's a simple matter of refactoring the rest of the system to be sane again.
I'm trying to get server-side validation of an Entity Framework String Property to work. Other server-side validation such as data type validation and required dateTime and numeric EF properties are working.
This in VS 2010, .Net 4.0, MVC2 + Cloud, ADO.Net Entity Framework.
The String Property I am having issues with is mapped to a SQL 2008, Varchar(50) non-nullable column.
When I try to post to my Create action with an empty string for this Property, I get the follwing error.
Exception Details: System.Data.ConstraintException: This property cannot be set to a null value.
When I post to the action with a blank space, I successfully get a required field validation message.
I have tried using Data Annotations and ClientSideValidation but there seems to be issues with ClientSideValidation working on partial views and jquery dialogs.
Here is the orginal autogenerated code from the entity framework.
[EdmScalarPropertyAttribute(EntityKeyProperty=false, IsNullable=false)]
[DataMemberAttribute()]
public global::System.String GradeTypeName
{
get
{
return GradeTypeName;
}
set
{
OnGradeTypeNameChanging(value);
ReportPropertyChanging("GradeTypeName");
_GradeTypeName = StructuralObject.SetValidValue(value, false);
ReportPropertyChanged("GradeTypeName");
OnGradeTypeNameChanged();
}
}
Depending on the signature of the Action method (CREATE or EDIT), the exception can occur before stepping into the method or within the method when UpdateModel() is called. The inner exception is at the line below from the model.designer.cs file.
_GradeTypeName = StructuralObject.SetValidValue(value, false);
I have been able to reproduce this on a simple mvc2 web application.
i was having the same problem for a while. I have found a piece of explanation here: http://mvcmusicstore.codeplex.com/workitem/6604 . To put it in a nutshell, the exception "System.Data.ConstraintException: This property cannot be set to a null value" is thrown by Entity's Property Validation. This validation is performed when your mvc application tries to bind the form field to the corresponding entity property( it's called PreBinding Validation, and it occurs when submitting the form). As the field is empty( therefore convert to null), the binder tries to bind a null value to the property, which violates the Non-Null constraint on your entity's property.
But if you post with a blank field ( that is different from empty, therefore null) Entity validation passes( as the property is not set to a null value anymore), and then your see the message from the "Required" annotation validation, that is performed after the prebinding (it's PostBinding Validation).
A workaround is to use the annotation [DisplayFormat(ConvertEmptyStringToNull = false)] that tells to the binder not to convert an empty string to null.
[Required]
[DisplayFormat(ConvertEmptyStringToNull = false)]
public string YourStringProperty { get; set;}
Hope, this helps!
This was very helpful. I'm using MVC3 and entity framework. I was passing my entities directly into the controller, but got the same error when the form was blank. With entity framework you can do data validation by editing the auto-generated code, but creating a separate partial class of the entity worked better for me.
[MetadataType(typeof(TestEntityValidation))]
public partial class TestEntity{
}
public class TestEntityValidation{
[Required]
[DisplayFormat(ConvertEmptyStringToNull = false)]
public String name { get;set}
}
Sometimes in database first approach in EF, may you update your column from not null to can be null using SQL query and use 'Update Model From Database...' (in EDMX right click) then maybe property of that entity not updated properly and so if you have some null data in that column ,in mapping ,violation occurs and this error shown.
To fix this; You can check the Nullable in Properties of that property of entity that you updated it.