i would like to create new entities which use the default values defined in the model.
i've checked the retrieved metadata, and the default values are there:
{"name":"LastName","type":"Edm.String","maxLength":"50","unicode":"true","fixedLength":"false","defaultValue":"admin:
Nachname"},
however they are not taken into consideration when creating a new entity.
This is a bug in Breeze that should be fixed in the next release, out in about week. When this fix gets in then breeze will honor any defaultValues it finds in the EntityFramework data model.
One problem though is while it is easy to get 'defaultValues' into a Model First Entity Framework model via the properties editor, it's actually difficult to get it into a Code First EF model, unless you use fluent configuration. Unfortunately, EF ignores the [DefaultValue] attribute when constructing Code First model metadata.
One workaround that you can use now is to poke the 'defaultValue' directly onto any dataProperty. Something like:
var customerType = myEntityManager.metadataStore.getEntityType("Customer");
var fooProperty = customerType.getProperty("foo");
fooProperty.defaultValue = 123;
Related
I have a scenario where I know the primary key of an entity (retrieved from an unrelated source), and I want to update just 1 property (db column). I have NOT already retrieved the entity from the database. If possible I would like to not have to make this extra round trip.
I create the entity using manager.createEntity.
I update one of the properties.
Then set the entityAspect to setModified();
When saving changes, all the properties that were not updated are set to their default values, and the generated SQL UPDATE statement attempts to update all mapped columns.
Is there a way to tell breeze to only generate SQL for specific properties/columns?
thanks
As you discovered, the properties of the originalValuesMap guide the Breeze server's ContextProvider as it prepares the save request. This is documented in the ContextProvider topic.
In your example, you call setModified after you've changed the property. All that does is change the EntityState; it doesn't create an entry in the client entity's entityAspect.originalValuesMap ... therefore the originalValuesMap sent to the server is empty.
I'm a little surprised that the EFContextProvider.SaveChanges prepared an EF update of the entire entity. I would have guessed that it simply ignored the entity all together. I'm making a mental note to investigate that myself. Not saying the behavior is "right" or "wrong".
You do not have to manipulate the originalValuesMap to achieve your goal. Just change the sequence. Try this:
var foo = manager.createEntity('Foo', {
id = targetId
}, breeze.EntityState.Unchanged); // create as if freshly queried
foo.bar = 'new value'; // also sets 'originalValues' and changes the EntityState
manager.saveChanges(); // etc.
Let us know if that does the trick.
I can't find any info about this in the documentation, so I will ask here. How does breeze handle database column defaults? I have required columns in my database, but there are also default static values supplied for these in the database column definitions. Normally, I can insert null into these columns, and the new records will get the default. However, breeze doesn't seem to be aware of database column defaults, and the entities that have null in these columns fail validation on saving.
Thanks,
Mathias
Try editing the edmx xml by adding StoreGeneratedPattern = "Computed" attribute to the column with default value in the DB.
Edit:
Actually, before doing editing the xml, try setting the StoreGeneratedPattern property to Computed in the model editor itself.
Update:
This was fixed in Breeze 1.4.6 ( or later), available now.
Original Post:
There is currently in a bug in Breeze that should be fixed in the next release, out in about week. When this fix gets in then breeze will honor any defaultValues it finds in the EntityFramework data model.
One problem though is while it is easy to get 'defaultValues' into a Model First Entity Framework model via the properties editor, it's actually difficult to get it into a Code First EF model, unless you use fluent configuration. Unfortunately, EF ignores the [DefaultValue] attribute when constructing Code First model metadata.
One workaround that you can use now is to poke the 'defaultValue' directly onto any dataProperty. Something like:
var customerType = myEntityManager.metadataStore.getEntityType("Customer");
var fooProperty = customerType.getProperty("foo");
fooProperty.defaultValue = 123;
I'm trying to update a backbone model, the server side is asp.net mvc 4. I'm getting:
"System.ArgumentException: An item with the same key has already been added" exception.
The reason is because backbone is sending Id and id to the server as properties, and the JsonValueProvider tries to add this to a dictionary.
Here is my model:
var Task = Backbone.Model.extend({
url: "/tasks/task",
idAttribute: "Id"
});
This is send to the server via Put request:
{"Id":294912,"Task":"test","DueDate":"2012-03-24T02:00:00.000Z", "id":294912}
Is there a way to prevent backbone in sending the "id" property?
The problem here is because the conventions in C# is not the same as in JavaScript. In C# classes have properties that starts with capital letters (Pascal Case) and it's the norm in JavaScript to start your properties in lower case (Camel Case).
Thus when serializing view models the default behavior of the JSON.NET serializer is to serialize the object exactly with the same capitalization of properties. I could rename the properties on the view model to be camel case, but it would be as "weird" as to have properties with pascal case in your JavaScript objects.
So instead to force Backbone into a non convention way, I've change the serialization of the objects to convert the Pascal case properties into Camel case properties by leveraging JSON.NET's Contract Resolver functionality.
var settings = new JsonSerializerSettings();
settings.ContractResolver = new CamelCasePropertyNamesContractResolver();
JsonSerializer serializer = JsonSerializer.Create(settings);
JsonConvert.SerializeObject(object, Formatting.None, settings);
Now this creates consistency on the client side with my code and with all the cool libraries out there.
Sounds to me like the issue is in your server-side code, not with the call from Backbone. A PUT is an edit operation on the server, so you're updating an existing entity. You need the ID property to identify the model on the server and update the properties that have changed.
If ASP.NET MVC is complaining that the model already exists in the database, you are trying to do an INSERT instead of an UPDATE. We'd need to see the controller and data access code to see where things are going awry.
UPDATE: What happens if you leave off the idAttribute property? From the Backbone documentation:
A special property of models, the id is an arbitrary string (integer id or UUID).
If you set the id in the attributes hash, it will be copied onto the model as a
direct property.
The id attribute should be sent by default; it looks like you're forcing it to be included a second time.
Under idAttribute in the docs:
A model's unique identifier is stored under the id attribute. If you're directly communicating
with a backend (CouchDB, MongoDB) that uses a different unique key, you may set a Model's
idAttribute to transparently map from that key to id.
ASP.NET MVC's model binding should be able to cope with id vs. Id.
UPDATE: Found a good blog post that describes using a view model to aid in serializing your C# objects into the format Backbone expects. This seems like a reasonable, if slightly annoying, solution.
I'm working on my first ASP.NET MVC (beta for version 3) application (using EF4) and I'm struggling a bit with some of the conventions around saving a new record and updating an existing one. I am using the standard route mapping.
When the user goes to the page /session/Evaluate they can enter a new record and save it. I have an action defined like this:
[ActionName("Evaluate")]
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult EvaluateSave(EvaluteSessionViewModel evaluatedSession)
{
}
When they save I grab an entity off the view model and attach it to my context and save. So far, so good. Now I want the user to be able to edit this record via the url /session/Evaluate/1 where '1' is the record ID.
Edit: I have my EF entity attached as a property to the View Model.
If I add an overloaded method, like this (so I can retrieve the '1' portion automatically).
[ActionName("Evaluate")]
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult EvaluateSave(ID, EvaluteSessionViewModel evaluatedSession)
{
}
I get an "The current request for action 'Evaluate' on controller type 'SessionsController' is ambiguous between the following action" error. I'm not sure why they're ambiguous since they look unique to me.
I decided that I was just going to skip over this issue for now and see if I could get it to update an existing record, so I commented out the EvaluateSave that didn't have the ID parameter.
What I'd like to do is this:
// Load the original entity from EF
// Rebind the postback so that the values posted update the entity
// Save the result
Since the entity is populated as the parameter (evaluatedSession) the rebinding is happening too soon. But as I look at the approach I'd like to take I realized that it opens my code up to hacking (since a user could add in fields into the posted back page and these could override the values I set in the entity).
So it seems I'm left with having to manually check each field to see if it has changed and if it has, update it. Something like this:
if (evaluatedSession.MyEntity.myField <> savedSession.myField)
savedSession.myField = evaluatedSession.MyEntity.myField;
Or, save a copy of the entity and make sure none of the non-user editable ones have changed. Yuck.
So two questions:
First: how do I disambiguate the overloaded methods?
Second: is there a better way of handling updating a previously saved record?
Edit: I guess I could use something like Automapper...
Edit 9/22/2010 - OK, it looks like this is supposed to work with a combination of two items: you can control what fields bind (and specifically exclude some of them) via the [Bind(Exclude="field1,field2")] attribute either on the class level or as part of the method doing the saving, ex.
public ActionResult EvaluateSave([Bind(Exclude="field1")] EvaluateSessionViewModel evaluatedSession)
From the EF side of things you are supposed to be able to use the ApplyCurrentValues() method from the context, ex.
context.ApplyCurrentValues(savedEval.EntityKey.EntitySetName, evaluatedSession);
Of course, that doesn't appear to work for me. I keep getting "An object with a key that matches the key of the supplied object could not be found in the ObjectStateManager. Verify that the key values of the supplied object match the key values of the object to which changes must be applied.".
I tried attaching the original entity that I had just loaded, just in case it wasn't attached to the context for some reason (before ApplyCurrentValues):
context.AttachTo(savedEval.EntityKey.EntitySetName, savedEval);
It still fails. I'm guessing it has something to do with the type of EF entity object MVC creates (perhaps it's not filled in enough for EF4 to do anything with it?). I had hoped to enable .NET framework stepping to walk through it to see what it was attempting to do, but it appears EF4 isn't part of the deal. I looked at it with Reflector but it's a little hard for me to visualize what is happening.
Well, the way it works is you can only have one method name per httpverb. So the easiest way is to create a new action name. Something like "Create" for new records and "Edit" for existing records.
You can use the AntiForgeryToken ( http://msdn.microsoft.com/en-us/library/dd492767.aspx ) to validate the data. It doesn't stop all attempts at hacking but it's an added benefit.
Additional
The reason you can only have one action name per httpverb is because the model binders only attempt to model bind and really aren't type specific. If you had two methods with the same action name and two different types of parameters it can't just try and find the best match because your intent might be clearly one thing while the program only sees some sort of best match. For instance, your might have a parameter Id and a model that contains a property Id and it might not know which one you intend to use.
I'm using Entity Framework with an AS.NET MVC application. I need to allow the user to create new records and modify existing ones. I am able to fetch existing records no problem, but when I pass back in the edited entity and try to save it it creates a new one and saves it and leaves the original unmodified.
I am getting the object from EF using the primary key (e.g. ID number for an employee record). I successfully retrieve it, and set the MergeOption like so:
Context.Sector.MergeOption = MergeOption.NoTracking;
I am able to trace that the object has the correct data (using the key of the original record) all the way down to the point where I call:
Context.SaveChanges();
However, after that, the new record is created instead of modifying the existing one.
Is there something obvious I am missing here? I would have thought that retrieving the object and changing some of its values (not the ID) and saving it would just work, but obviously not.
Thanks,
Chris
"NoTracking means that the ObjectStateManager is bypassed and therefore every access to the Entity Objects results in a fetch from the database and the creation of new objects."
-- http://blog.dynatrace.com/2009/03/11/adonet-entity-framework-unexpected-behaviour-with-mergeoptions/
I don't think NoTracking is what you want.
From your comment: "distributed across various tiers and some proprietary libraries"
Are you new()ing up a ObjectContext, closing it or losing the reference to it, and then trying to save your object to a new() or different ObjectContext?
If so your losing all of your change tracking information. If this is the case then you want to call the Attach() method to reattach the entity to the context, ApplyPropertyChanges() and then finally SaveChanges().
Julie Lerman has a pretty good blog post that outlines all the different change tracking options and techniques that are available. You should also check out this MSDN article on the same subject.