I have a class called LoginCommand in domain/my/package/name
class LoginCommand {
String emailAddress
String password
}
My question is why is a table be auto generated in my database for a ***Command object in grails? Are these command objects supposed to be placed ouside of /domain to avoid auto generation of a table by hibernate/orm.
They should not go in grails-app/domain; they are not domain classes. Place them in src/groovy. Alternatively, a common convention is to put the command class in the same file as the controller that uses it.
Take a look at the Convention Over Configuration section in the grails manual to get an idea of what goes where.
Related
Let's say i have the following classes:
package test
class Person {
String name
static hasMany = [stuff:Stuff]
static constraints = {
}
}
and
package test
class Stuff {
String stuff
static belongsTo = Person
static constraints = {
}
}
When i implement the view for Person i want to be able to select from a list of previously created stuff. How do i achieve that? I see that, when i use scaffolding Grails generates that drop down menu where i can do that but since i a designing my own views i would like to understand how that is done.
Thank you.
Probably good to start be reviewing the documentation for the select tag here: https://gsp.grails.org/latest/ref/Tags/select.html
A simple example to present a list of all Stuff would look like:
<g:select name="stuffSelect" from="${Stuff.list()}" optionKey="id" optionValue="stuff"/>
This should give you a dropdown of all Stuff in your database, displaying the String value to the user, but submitting the DB ID when the form submits.
I'm pretty sure you can use the generate-all command in grails, to see what the scaffolding code looks like:
http://docs.grails.org/3.1.1/ref/Command%20Line/generate-all.html
Using this command should generate Controllers, views, etc. so you can see how the scaffolded code works. Don't worry about being able to go back to generated scaffold code, just delete the stuff created by generate-all, and grails will autogenerate it at runtime like it does now.
I use inheritance in Domain Classes in my Grails app. Obviously, inheritance adds a "class" column to my database. The content of the "class" column is the fully qualified name of the Domain Class, e.g. com.myapp.MyClass.
Now if I ever so some refactoring and the class name is no longer com.myapp.MyClass but e.g. com.myapp.mypackage.MyClass, then the database still contains the old class name which now no longer exists in the app.
Is there any way to configure the string that is put in the "class" column? Like another unique identifier for the class which is then mapped to the class name in my Grails config or something like this?
I think what you need is discriminator for the class.
By default when mapping inheritance Grails uses a single-table model
where all classes share the same table. A discriminator column is used
to determine the type for each row, by default the full class name. ref
You can map it like this:
class PodCast extends Content {
…
static mapping = {
discriminator "audio"
}
}
Look this documentation it gives you more options to customize it in more details
http://grails.org/doc/latest/ref/Database%20Mapping/discriminator.html
I was creating an mvc application and i had a model class with a dbcontext function the variables were in the same file. I added another field and changed the code in the edit create delete details and index views but i now get an error saying
"The model backing the 'GameDBContext' context has changed since the database was created. Either manually delete/update the database, or call Database.SetInitializer with an IDatabaseInitializer instance. For example, the DropCreateDatabaseIfModelChanges strategy will automatically delete and recreate the database, and optionally seed it with new data."
Imports System.Data.Entity
Public Class Game
Public Property ID() As Integer
Public Property Name() As String
Public Property Genre() As String
Public Property Price() As Decimal
Public Property Developer() As String
End Class
Public Class GameDBContext
Inherits DbContext
Public Property Games() As DbSet(Of Game)
End Class
you need to add a initializer method to the Application_Start method in Global.asax file. Ex:-
Database.SetInitializer(new DropCreateDatabaseIfModelChanges<GameDBContext>());
Since it sounds like you're using a code first approach in developing your application, here are a couple of links that might help you:
code first development with entity framework 4
Code First/Entity Framework 4.1 Videos and Articles on MSDN
All of these can give you a better understanding of what is happening and how to work around having your database change on you.
In short, since you added another property, the entity framework table in your database is now longer in sync with your class. Since it's no longer in sync, you must manually delete this database in order to regenerate it, or you must create an initialization for the database. All of these concepts are better described in the links I have provided.
Good luck, and hope these help you some.
I am following the tutorial on sharparchitecture.net. I have created a few entities using T4, but I can't figure out where the mapping to the database is done?
I would like to create some relations in the mapping files, but should I add a new mapping file or are there already created one with T4?
SharpArchitecture uses FluentNHibernate to automagically create NHibernate mappings based on your Entities as defined in project PROJECT.Core. It will define relationships based on the domain model. You will find that you frequently need to customize your mappings.
The project PROJECT.Data is where you will perform overrides to the default mapping. In this project you will find a folder called NHibernateMaps with several classes to setup the default mapping strategy. Step 1 would be to evaluate the default mapping strategy to see if you need to make any systemwide changes to the default strategies. Second, you may want to override a mapping for an specific entity. To do this create a new class called [EntityClass]Map that looks like the following:
public class EntityMap : IAutoMappingOverride<Entity> {
public void Override(AutoMapping<Entity> mapping) {
//use the mapping. to override default mappings. Here is just an example
mapping.References(x => x.EntityCategory).Fetch.Join();
mapping.References(x => x.EntitySubItem).NotFound.Ignore();
}
}
Your application ties this all up in the InitializeNHibernateSession method within the global.asax.cs.
I've created a one table contact DB, which has only 3 columns (Id, Name, and Phone). I've then created the ContactsDataContext using my table Contacts in the model folder. Finally, I create a partial class still in the model folder (public partial class Contact).
now when I write this
public partial class Contact
{
public string MyContact
{
get
{
string name = this.Name ?? String.Empty;
}
// ... Other lines omitted
}
}
I get the following error :"'ContactsManager.Models.Contact' does not contain a definition for 'Name' and no extension method 'Name' accepting a first argument of type 'ContactsManager.Models.Contact' could be found (are you missing a using directive or an assembly reference?)"
Is something wrong??? Even the Intellisense in not showing the properties from my DataContext class. Yet, I've written some partial classes in the past with no problem.
Thank you.
Are namespaces the same on the two partials?
Chris Roden,
Yes, I've resolve it. In fact, I've asked the above question many months ago when I started learning ASP.NET MVC. I bought a book called "ASP.NET MVC - The Beer House/Nick Berardi/Wrox." Is a god book, but it's not recommendable for beginners. Generaly, things are thrown like that without telling where they come from.
The response came from applying the definition of a partial class. Among others, partial classes must:
have the same name
be preceded by 'partial' keyword,
be defined in the same namespace,
etc.
If you miss any of the above criteria, then you'll be in trouble because those criteria, ll be used to merge all the partial classes into a unique one.
In my case, I created a table called ContactDB. After I've created the datacontext class, I've dropped the ContactDB table on the Linq2Sql editor. As you must know, that creates the following class:
public partial class ContactDB
{
//All the columns in the table become properties in this class
}
The partial keyword allow me to write this:
public partial class ContactDB
{
//I can reference members of the above partial class... using this keyword
//After all, the 2 constitute one class.
}
After reading the definition of partial classes, I found out that I failed one of the criteria. I called my other partial class "Contact" which's different from ContactDB. That was enough to make me go crazy for 3 days until I read the definition. Moreover, if you defines the partial class with the right name but you put it in a different namespace, you'll get in trouble as well.
So, if the above answer doesn't work for you (I don't know exactly your problem), check the definition of the partial class.Don't forget to read the ScottGu's series on Linq2Sql.
Hope it helps.