I am new to Entity Framework. I started with database first approach which created my classes corresponding to the tables I selected. I am using WPF. Unfortunately there is a problem occurred while EF6 was mapping classes. The assigned type for a field is byte while in some cases the value exceeds the byte constraints. So, I want to replace it with either int or double. How do I change the model field types without any changes made for the used database?
namespace DataChrome{
public partial class REGISTRY_MEST{
public byte MEST { get; set; } //Wrong typed field
public string MESTNAME { get; set; }
public Nullable<byte> IDSTRAT { get; set; }
public Nullable<int> MESTOLD { get; set; }
}
}
So, giving 7 hours to this problem I found the right solution. All you need is just to set user mapping rules in appconfig file. For more details: visit this page.
The type change should be possible by editing the edmx model: click the MEST property of the class inside the edmx model, then set the Type accordingly in the Properties Window and save the model.
You are running a risk by doing this, as it might be possible to store a value too big for the column if you just change the type this way. You noted that you are using Oracle as the underlying DB, so it might very well be the case that EF generated a "wrong" type for that property.
If you are absolutely sure that the DB will accept the expanded type (int, double) then it should be safe to edit the property as I mentioned at the start. Otherwise you would have to change the DB and generate the class anew - you might need to delete the class from the model and add it again, because not all changes to the table are picked up by the automatic update process.
Related
I am wondering if it makes sense to create a migration for a scenario where there aren't necessarily model changes, but the enum property on a model has been changed. I'm using .NET 4.6.2 and Code-First Entity Framework
I have the following EF-tracked log model:
[Table("Logs")]
public class Log
{
public int Id { get; set; }
public DateTime Timestamp { get; set; }
public LogType Type { get; set; }
}
The LogType enum currently has around 40 values, of which, 13 have become obsolete or deprecated. I am going through the process of removing references to the obsolete/deprecated enum values.
As such, the values of the LogType enum are being changed. For example, LogType.ConnectionTimeout used to have the value 16, but now has the value 3.
In my database (MSSQL), the Type column is stored as an int, and I have written SQL that deletes all entries with an obsolete/deprecated enum value, and I have also written SQL that updates the other enum values to match what their new values are (e.g. changing 16 to 3 using my previous example of Type.ConnectionTimeout).
My question is this: Is it a good practice to put that SQL in a migration that is able to be Up()'d and Down()'d? My other question is, is that even possible? Or does there need to be actual model changes to create a migration? I'd like to be able to have this SQL tracked and stored in version control, as well as the ability to Up() and Down() it in the future if need be.
Thanks, and apologies in advance if this is a duplicate -- I wasn't able to find a similar question through my searches.
Here is the super simple class I'm trying to create.
public class Company
{
public int ID { get; set; }
[Column(TypeName = "VARCHAR(254)")]
[Index]
public string Name { get; set; }
[Index]
public int stupidField { get; set; }
}
My goal was to force Name to be unique, so I added the decoration [Index(IsUnique = true)]. But no unique index was created, so I figured I'll first try to solve the simpler problem of creating any index. Because I read here that indices cannot be created for columns of type varchar(max), I limited the length of the Name field. Still no luck. I even tried a few different syntaxes for limiting the length of the field, but still no index.
To see if something other than string length was at play, I created the integer field stupidField, but I can't index that field either. So now I'm completely out of ideas as to what could be wrong. Please help me!
Check out this screenshot from MS SQL Server Management Studio that shows that my fields are being created but not the indices.
Note: I'm certain migrations are not the issue.
Some of the people I've read about on SO were updating their classes, but those changes were not reflected in the database because of problems with their migrations. That is not relevant here. I delete the database and recreate it every time I make a change. (I even make silly changes like renaming my fields, just to make sure that I can still affect the database.)
Turns out I'm actually using Entity Framework Core, not Entity Framework. In Entity Framework Core, indices cannot be created using attributes, although they can be created using fluent API. See Microsoft's documentation.
Using : dotnet core 1.1, entity framework code first, sql server.
Is there any elegant way to enable a user working on a large form, represented by a complexe model (40+ tables/C# objects), having multiple "required" fields, to save it's work temporarily and come back to complete it afterward?
Let's say I have this model :
[Table("IdentificationInfo", Schema = "Meta")]
public class IdentificationInfo : PocoBase
{
[...]
public int MetaDataId { get; set; }
[ForeignKey("MetaDataId")]
public virtual MetaData MetaData { get; set; }
public int ProgressId { get; set; }
[ForeignKey("ProgressId")]
public Progress Progress { get; set; }
public virtual MaintenanceInfo MaintenanceInfo { get; set; }
public int PresentationFormId { get; set; }
[ForeignKey("PresentationFormId")]
public PresentationForm PresentationForm { get; set; }
private string _abstract;
[Required]
public string Abstract
{
get { return _abstract; }
set { SetFieldValue(ref _abstract, value, "Abstract"); }
}
[...]
}
[Table("PresentationForm", Schema = "Meta")]
public class PresentationForm : PocoEnumeration
{
[...]
}
The user starts to fill everything (in a big form with multiples tabs or really long page!), but needs to stop and save the progress without having the time to save to fill the PresentationForm part, nor the abstract. Normally, in the database, those fields are not null, so it would fail when we try to save the model. Similarly, it would also fail with EF validation in the UI.
What would be nice is using the Progress property and disable EF model validation (model.isValid()), and also enable database insert even if the fields are null (it is not possible to put default values in those not nullable fields as they are often foreign keys to enum like table).
For the model validation part, I know we can make some custom validator, with custom annotation such as [RequiredIf("FieldName","Value","Message")]. I'm really curious about some method to do something similar in the database?
Would the easy way to do that be to save the model as JSON in a temporary table as long as the progress status is not completed, retrieve it when needed for edition directly from the JSON, and save it to the database only when the status is completed?
To support (elegantly) what you ask you should design it that way.
One table with it's required columns should be minimum segment that have to be inputted before any save. Should make segment optimal size.
You could set all fields to allow null but that would be very BAD design, so I would not consider that option at all.
Now if your input consist of several logical parts, and on form they could be different tabs so each tab is in one table in Db and main table have FKs of others tables.
That FK could be Nullable, and it would enable you to finish say first 2 tabs, Save it, and leave rest for after. So you will know that those FK column that have values are finished(and maybe could be edited still), while others are yet to be inserted. You can also have column Status:Draft/Active/...
What's more this design would allow you to have configurable tabs, so for example based on some chosen selection on main input you could chose what tables can be inputted, and which not and to enable/disable appropriate tabs.
If however you don't want FKs nullable than solution would be some temporary storage, one option being JSON in one string column, as you have mentioned your self. But I see no issues with nullable FKs in this case.
i've recently added a new property to one of my models:
public HttpPostedFile AvailabilityImage { get; set; }
However, upon doing so I'm now getting this very strange error:
error 3004: Problem in mapping fragments starting at line 32:No mapping specified for properties FloorModel.AvailabilityImage in Set Floor
I am at a loss on how to solve this, I've never had this issue adding properties before?
Is it to do with the Data type being used with this property do you think? Any suggestions are welcome
Thankyou
HttpPostedFile is a complex type and contains many aspects to it that cannot be properly serialized. For example, it contains a property that references the current HttpResponseStream. This will be different every time you make a connection, so you can't serialize this.
I doubt what you are trying to do is correct anyways. Are you trying to save the file that is uploaded? If so, then you need to save the actual binary contents.. not the HttpPostedFile.
The framework could of auto-generated a new DbSet with a complex data type. It has happened to me when I'm building models and passing DbSet data types under the model constructor. Go verify the model and remove any complex data types and comment out any DbSet related to that model.
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
.
.
.
public System.Data.Entity.DbSet<Solution.Models.Model1> Model1 { get; set; }
//Comment out possible Model and try debugging again.
//public System.Data.Entity.DbSet<Solution.Models.Model2> Model2 { get; set; }
}
I've a table with 52 columns in my database and I want to write a function to create a row in that table.
In my case, I don't want to use all columns in that table, so I created my model like this.
[Table("CUST_MASTER")]
public class CustomerMaster
{
[Key]
[Column("CUSTOMER_ID")]
public string Id { get; set; }
[Column("CUSTOMER_NAME")]
public string Name { get; set; }
[Column("CUSTOMER_CITY")]
public string City { get; set; }
}
Is there any way to send only this data via Entity framework and set all other not nullable fields to some default data(for strings "", for decimals 0.0, etc.) without writing all that fields in my model and doing it manually?
When you do not incorporate a Table-column in your model then it won't be mapped and it will be totally ignored by all generated SQL.
So the only option is to specify a default value in your Database.
If you set the values in the constructor you will have a default value through your code, but you could look into enabling migrations instead, this way you can set default values. look at this stackoverflow question
I think this old suggestion is what you want. It explicitly mentions the lack of mapping between the conceptual model and the storage model. Not a very popular/understood idea though.
Update: FWIW, this suggests that it is already possible in non-Code-First scenarios.