I am in the process of trying to copy the properties of one domain object to another similar domain object (Basically moving retired data from an archive collection to an active one). However, when I try to save with a manually inputed id the save will not actually put anything into the collection.
def item = new Item(style: "631459")
item.id = new ObjectId("537da62d770359c2fb4668e2")
item.save(flush: true, validate: false, failOnError:true)
The failOnError does not throw an exception and it seems like the save works correctly. Also if I println on the item.save it will return the correct id. Am I wrong in thinking that you can put a specific id on a domain object?
You can set the id generator as 'assigned' so then you can put the value that you want and is going to be saved with that value.
class Item {
...
static mapping = {
id generator:'assigned'
}
}
The identifier id is a somewhat sensitive name to use. If you check your dbconsole, you will find that GORM has provided one for you even without asking. When you use that name for yourself, confusion happens. Grails will respect you with the println stuff, but GORM has the last word on how id gets initialized and stored, and it is not listening to you then.
You can rename the id to something else like you see in this post and maybe then you can use the name id for yourself. Otherwise, I suggest leaving id to GORM, and have your own identifier for your old keys. You won't have problems retrieving data anyway and there won't be performance issues.
Related
In my Grails App, I have bootstrapped an object of a domain class as:
def user1 = new Users(userID: 1, name: "John Doe")
user1.save()
In my dashboard controller i have retrieved the object and modified its property name as:
Users userObj = Users.get((Long) 1)
println(userObj as JSON); // This gives me: {"class":"com.prabin.domains.Users","id":1,"name":"John Doe"}
userObj.name = "anonymous"
Now i create a new Users object to retrieve the changed object with same ID 1 as
Users otherUserObj = Users.get((Long) 1) // **Line 2** Is this retrieving from database or from GORM session?
print(otherUserObj as JSON)// This gives me: {"class":"com.prabin.domains.Users","id":1,"name":"anonymous"}
But the value of object in database is not changed. And even when i retrieve the Users object of same id 1 in another controller it gives me the initial object rather than the modified as:
Users userObjAtDifferentController = Users.get(1);
print(userObjAtDifferentController) //This gives me: {"class":"com.prabin.domains.Users","id":1,"name":"John Doe"}
My question is, if the value is not changed in the database, why it gives me the modified object at Line 2 though i have retrieved the object using GORM query (which i guess should retrieve from the database)?
I have also tried using save() after the modification but the result is same.
userObj.save() //doesn't show the changes in database.
My guess is that the object is not being saved to the database because some constraint(s) are invalid. You can determine whether this is the case by replacing your calls to save() with save(failOnError: true). If my guess is correct, an exception will be thrown if saving to the database fails.
When you call the save() method on a domain object, it may not persist in the database immediately. In order to persist the changed value to the database, you would need to do the following.
userObj.save(flush: true)
By using flush, you are telling GORM to persist immediately in the database.
In some cases when validation fails, the data will still not persist in the database. The save() method will fail silently. To catch validation errors as well as save to the database immediately, you would want to do the following
userObj.save(flush:true, failOnError:true)
If validation errors exist, then the GROM will throw ValidationException (http://docs.grails.org/latest/api/grails/validation/ValidationException.html)
You need to consider two things:
If you do save(), it only retains in hibernate session, until you flush it the changes does not persist in database. So, better do save(flush:true, failOnError: true) and put in try/catch block and print exception.
And another important things is, your method in controller needs to be with #Transactional annotation, without it your changes does not persist in database, you will encounter Connection is read-only. Queries leading to data modification are not allowed. exception.
Hope this helps, let me know if your issue is fixed. Happy coding . :)
Constantly faced with a problem when I need to compare and manipulate objects that reference other objects. For example:
Class Student {
...
String Name
Integer Age
...
}
Class Stuff {
...
Student student
...
}
When I invoke an instance of Stuff (Stuff.get (id)/load(id)) and will access the Name, Age and other attribute I see in debug mode (stuff .name = null, they're like 'null' although they are not null. It
command when analyzing values of these attributes (stuff
.name == "pen") error occurs.
I need to invoke the instances and compare their values to execute business rules, but do not know how to resolve this issue.
I read something about the inclusion in the configuration Stuff Mapping 'student lazy: false' for all the time you need to load the instance ofstuff , also charge the Student, but that in addition to overload the memory (since stuff is a Domain Great) would solve this case being the only solution to put all references as 'lazy: false' which would slow the application just to make a simple comparison.
Does anyone know how to invoke instances (Stuff), automatically invoking the attribute to be working (student) just to make the comparison of data, without using the 'student lazy: false' that invokes the data at all times?...
Using Grails 2.2.0 e o Groovy 2
Stuff don't have a property called name so you should get MissingPropertyException calling stuff.name. This has nothing to do with the lazy or eager relationship.
You can check the definition of a lazy relationship in the documentation and also the difference between the types of fetch.
To access the name property you need to access the student property before:
Stuff instance = Stuff.get(id)
println instance.student.name //this, if lazy, will trigger a new database query.
If you know that your code will access the Student instance by the relation with Stuff you could fetch both in one database access (eager and not lazy):
Stuff instance = Stuff.withCriteria {
eq('id', id)
fetchMode("student", FetchMode.JOIN)
}
I'm looking for the best solution to implement this behavior:
I have an Entity called Customer and this will have only a single entry on Core Data, because the Customer will be only ONE.
What's the best solution to implement this? Is everytime check if the Entity exists before creating?
Many thanks
As mentioned, you can use for single object [NSUserDefaults standardUserDefaults].
But if you prefer use CoreData, write this:
Customer* customer = [Customer MR_findFirst];
if (customer != nil)
{
//do something with it
} else
{
[Customer MR_importFromObject:JSONToImport];
}
BDW:
MR_importFromObject method automatically check if exists entity with specific id (for id key it use attribute of your entity name plus "ID". (in your case "customerID") or key that named "mappedKeyName".
And if entity with this key already exist - Magical Record just update this entity.
So, if you specify this value it in your entity, just write:
[Customer MR_importFromObject:JSONToImport];
If there's only a single instance, the best solution is usually to not put it in Core Data. It gives you very little, and adds complexities like the one you're seeing. Save the necessary information in a property list, or even in user defaults.
Checking the entity exists before creating a new one is a good idea.
You can fetch all entities of your customer entity type and delete them all before adding a new one is another method.
You could also have a simple method that gets the current customer or creates one and then update all it's properties.
It sort of depends on how you get the data and what you want to happen with the related objects.
I am looking for a simple way to hydrate a related object. A Note belongs to a Document and only owners of a Document can add Notes so when a user tries to edit a Note, I need to hydrate the related Document in order to find out if the user has access to it. In my Service layer I have the following:
public void editNote(Note note)
{
// Get the associated Document object (required for validation) and validate.
int docID = noteRepository.Find(note.NoteID).DocumentID;
note.Document = documentRepository.Find(docID);
IDictionary<string, string> errors = note.validate();
if (errors.Count > 0)
{
throw new ValidationException(errors);
}
// Update Repository and save.
noteRepository.InsertOrUpdate(note);
noteRepository.Save();
}
Trouble is, noteRepository.InsertOrUpdate(note) throws an exception with "An object with the same key already exists in the ObjectStateManager." when the repository sets EntityState.Modified. So a number of questions arise:
Am I approaching this correctly and if so, how do I get around the exception?
Currently, the controller edit action takes in a NoteCreateEditViewModel. Now this does have a DocumentID field as this is required when creating a new Note as we need to know which Document to attach it to. But for edit, I cannot use it as a malicious user could provide a DocumentID to which they do have access and thus edit a Note they don't own. So should there be seperate viewmodels for create and edit or can I just exclude the DocumentID somehow on edit? Or is there a better way to go about viewmodels such that an ID is not required?
Is there a better way to approach this? I have read that I should just have a Document repository as an aggregate and lose the Note repository but am not sure if/how this helps.
I asked a similar question related to this but it wasn't very clear so hoping this version will allow someone to understand and thus point me in the right direction.
EDIT
Based on the information provided by Ladislav Mrnka and the answer detailed here: An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key, it seems that my repository method need to be like the following:
public void InsertOrUpdate(Note note)
{
if (note.NoteID == default(int)) {
// New entity
context.Notes.Add(note);
} else {
// Existing entity
//context.Entry(note).State = EntityState.Modified;
context.Entry(oldNote).CurrentValues.SetValues(note);
}
}
But how do I get the oldNote from the context? I could call context.Entry(Find(note.NoteID)).CurrentValues.SetValues(note) but am I introducing potential problems here?
Am I approaching this correctly and if so, how do I get around the exception?
I guess this part of your code loads the whole Node from the database to find DocumentID:
int docID = noteRepository.Find(note.NoteID).DocumentID;
In such case your InsertOrUpdate cannot take your node and attach it to context with Modified state because you already have note with the same key in the context. Common solution is to use this:
objectContext.NoteSet.ApplyCurrentValues(note);
objectContext.SaveChanges();
But for edit, I cannot use it as a malicious user could provide a DocumentID to which they do have access and thus edit a Note they don't own.
In such case you must add some security. You can add any data into hidden fields in your page but those data which mustn't be changed by the client must contain some additional security. For example second hidden field with either signature computed on server or hash of salted value computed on server. When the data return in the next request to the server, it must recompute and compare signature / hash with same salt and validate that the passed value and computed value are same. Sure the client mustn't know the secret you are using to compute signature or salt used in hash.
I have read that I should just have a Document repository as an aggregate and lose the Note repository but am not sure if/how this helps.
This is cleaner way to use repositories but it will not help you with your particular error because you will still need Note and DocumentId.
I'm feeling a little slow today. I'm trying to do something that I think is very simple. I have a Domain class with a property called 'name'. I want 'name' to have an index, and I want the index to require that the 'name' is unique. I've set the unique constraint and tried creating an index. I can't make sense out of the Gorm docs as to how I add the unique attribute to the index. Here's some code:
class Project {
String name
static hasMany = [things:Things]
static mapping = {
name index:'name_idx'
}
static constraints = {
name(unique:true)
}
}
All is well with the above, except when do "show indexes from project" in mysql it shows my name key as not unique. I know the problem is that I am not specifying unique in the mapping, but quite frankly the docs for gorm are making my head hurt. I see all kinds of stuff about columns, but I can't find a single example anywhere on the web that shows what I want to do. I don't need complex mappings or compound keys, I just want to know the syntax to add the unique attribute to the mapping declaration above. Any advice welcome.
I also did a grails export-schema and see the following:
create index name_idx on project (name);
Nothing in that to indicate this index requires unique values
A related followup question would be once I succeed in making that index unique, what type of error should I expect when I go to save a Project instance and the name is not unique? Is there a specific exception thrown? I realize that even if I check that a given 'name' is unique there's still a possibility that by the time I save it there may be a row with that name.
I'm quite sure the syntax to do what I want is simple but I just can't find a simple example to educate myself with. I've been to this page but it doesn't explain HOW the uniqueness is enforced. I'd like to enforce it at the name index level.
The indexColumn allows additional options to be configured. This may be what you're looking for.
static mapping = {
name indexColumn:[name:'name_idx', unique:true]
}
Grails Documentation for indexColumn
If you put only the unique constraint the GORM send DDL to create an unique index on database.
static constraints = {
name nullable: false, unique: true
}