I have an entity named Person that may have one home, and an entity named Home that may have one to N homes:
Then I have two array controllers:
Homes Controller, bound with managed object context, in entity mode: Home;
People Controller, bound with managed object context, in entity mode: person.
I have a cell based table view, bound with the People Controller.I am able to display successfully the first three columns (name, surname and age), but the problem is with the 4th column: the home's name.Inside the column there is a popup button cell, these are the bindings:
Content: Homes Controller.arrangedObjects ;
Content values: Homes Controller.arrangedObjects.name;
Selected object: People Controller.home.
The problem comes at runtime, when I try to click to the popup button to choose the home:
Like you see instead of the choice I see "Core data relationship fault", and if I try to change the home by clicking on the menu items, I see a lot of code printed to the console, I post only the most significant line:
2012-11-04 01:47:45.181 Test[4390:303] [<NSManagedObject 0x100156e60> valueForUndefinedKey:]: the entity Home is not key value coding-compliant for the key "(null)".
And after this the application freezes.
Edit: With some debug I am now able to know the state of the object when the exception occurs:
2012-11-09 02:42:02.495 Test[4650:303] <NSManagedObject: 0x100157460> (entity: Person; id: 0x10013d9d0 <x-coredata:///Person/t0182F6F4-9CCC-4F51-A82F-D00CE026DB752> ; data: {
age = 20;
home = "0x101953480 <x-coredata:///Home/t0182F6F4-9CCC-4F51-A82F-D00CE026DB753>";
name = "New Name";
surname = "New Surname";
})
2012-11-09 02:42:02.497 Test[4650:303] <NSManagedObject: 0x101953420> (entity: Home; id: 0x101953480 <x-coredata:///Home/t0182F6F4-9CCC-4F51-A82F-D00CE026DB753> ; data: {
name = "New Home";
people = (
"0x10013d9d0 <x-coredata:///Person/t0182F6F4-9CCC-4F51-A82F-D00CE026DB752>"
);
It seems that the values are regular, there are not nil keys.I suspect the problem is with the bindings.
It's hard to tell what is actually going on without seeing how you are fetching objects and their relationships from Core Data.
But, just because you see the word "fault" doesn't actually mean that there is a problem. A Core Data Fault just means that the data hasn't been retrieved from the store into the Managed Object Context yet.
Faults are very handy. They are like little stubs that stand in for objects in a relationship so that you don't pull too much into memory. It's only when you try to access the objects that they are swapped out for the actual objects.
See Core Data Relationship Fault for a bit more explanation.
Home-people and Person-home need to be declared as inverse relationships of one another using the model builder in order to function properly. The relationship will then appear as a single line.
Related
I'm following Sulu example here: https://github.com/sulu/sulu-workshop/
trying to set translations for custom entity type.
My entity file has getter for field "home_team" defined like:
/**
* #Serializer\VirtualProperty(name="home_team")
*/
public function getHomeTeam(): ?string
{
$translation = $this->getTranslation($this->locale);
if (!$translation) {
return null;
}
return $translation->getHomeTeam();
}
So field is not actually part of that entity, but of it's translation entity since it suppose to be translatable.
When I try to create new object of that entity type it works well. I can see in database that field values are stored well and I don't get any error.
But on overview page instead of list of all objects I get error:
[Semantical Error] line 0, col 73 near 'home_team AS': Error: Class App\Entity\MatchEvent has no field or association named home_team
Any idea what could be wrong here?
If you wanna see the translation in the listView you have to create a real translationEntity, like in the workshop project. In this post it is already explained, how to translate a custom entity correctly.
If you have already created your translationEntity you have to configure the relation of the translation to your main entity via a join. Here is an example in the workshop for this configuration.
Sulu uses optimised queries to create the list-object directly from the database. So the entity itself does not get hydrated or serialised for performance reasons. Thus your virtualProperty is never executed.
I have a many to many relationship table with payload (additional field) coming from .Net WebAPI that I have modelled in ember-data. When I add a record into this table/relationship ember is creating an additional record that is held in memory until the user performs a browser page refresh. My models are:
// student.js
export default DS.Model.extend({
name: DS.attr('string'),
studentsClasses: DS.hasMany('student-class')
})
// class.js
export default DS.Model.extend({
desc: DS.attr('string'),
studentsClasses: DS.hasMany('student-class')
})
// student-class
export default DS.Model.extend({
studentId: DS.attr('string'),
student: DS.belongsTo('student'),
class: DS.belongsTo('class'),
grade: DS.attr('number') // payload
})
Here is the code I use to create and add the many to many record.
let newRecord = this.get('store').createRecord('student-class');
newRecord.studentId = 1;
newRecord.grade = 3;
class.get('studentsClasses').pushObject(newRecord);
The new record gets created and added and everything looks good on screen, until I come back to the same page and there is an extra record in the class.studentClasses array.
Any idea why ember-data is creating an extra record in memory and how I can stop it doing it please?
Thanks
As you said, ember-data keeps records in memory. And you must keep in mind that ember-data will not remove those records by it own. It can only be removed from memory by yourself, page refresh or replaced by new payload if has same id property. You can observe that behavior by using ember debug plugin for browsers like chrome and firefox.
In your case, you've created a new record by store.createRecord(). In this moment, it had added this record to your memory already, and it was pushed to your class record. If you didn't save these models successfully, it will keep in a status called 'dirty', and if you never clean your store memory (using something like store.unloadRecord() which has some side effects, or remove this unsaved new record from your related model), the next time you use store.findRecord() to find a record, useless you force record to be reloaded like store.findRecord('class', 1, {reload: true}), it will use the existing data in your memory as first priority.
So my suggestion for this is to force reload this class model when entering this class page.
What is the best way to rehydrate your store during app initialization, specifically the references between stores?
For instance, lets say I have 2 api calls:
/todos -> return array of todos
[{id: 1, person_id: 2}]
/persons -> return array of Persons
[{id: 2, name: 'John'}, {id: 3, name: 'Sam'}]
and a Todo object looks like this
class Todo {
...
#observable person;
...
}
Some of the Todos will have a reference to a Person, but not all of them, and not all of the Persons will be referenced, so its not as simple as just scrapping the Persons api call and just returning the Person reference with the Todos api call.
However, we can't be sure that the Persons api call will be returned first, so we cannot just assume to link up the Todo / Person reference whenever the todos response arrives (would like to run calls in parallel)...
Is it just a matter of extra logic in the client side code to ensure we set up all references whenever the data comes in? Or is there some better practice anyone has found in there experience.
EDIT
The more I think about it, I'm thinking the most predictable logic would be to always either get or create a reference object.
So in the above example, if the Todos response comes in first, we would look for the Person object with the id of 2, if it exists great, if it doesn't, create it and reference that object. Then when the persons response comes in it would do the same thing...look for Person with the id of 2, if it exists, update it with the new data, if not, create it.
Anyone have any better ideas?
The simplest way is indeed to load your objects in order, and find them. After that to load them in parallel, and find-or-create placeholders if you refer to them. It's quite a common pattern.
I am a beginner to sencha Touch, basically i am a blackberry developer. Currently we are migrating our application to support Sencha Touch 1.1. Now i have some business solutions like i want to store the selected values in the local database. I mean i have multiple screens where, Once the user selects a value in each of the screen the data should save in the below following format.
[{'key1': "value1", 'key2': "value2", 'key3': "value3" ,'key4': "value4", 'key5': "value5"}]
1. First, the values need to be saved in key value pairs
2. The keys should play the role of primary key, key shouldn't be duplicated.
3. Should be available till the application life cycle or application session, don't need to save the data permanently.
I have come across the concepts like LocalStorageProxy, JsonStore and some others. I don't understand which one i can use for my specific requirements.
May be my question is bit more confusing. I have achieved the same using vector, in Blackberry Java so any data structure similar to this could help me. Need the basic operations like
Create
Add
Remove
Remove all
Fetch elements based on key
Please suggest me some samples or some code snapshots, which may help me to achieve this.
Edit: 1
I have done the changes as per #Ilya139 's answer. Now I am able to add the data with key,
// this is my Object declared in App.js
NSDictionary: {},
// adding the data to object with key
MyApp.NSDictionary['PROD'] = 'SONY JUKE BOX';
//trying to retrieve the elements from vector
var prod = MyApp.NSDictionary['PROD'];
Nut not able to retrieve the elements using the above syntax.
If you don't need to save the data permanently then you can just have a global object with the properties you need. First define the object like this:
new Ext.Application({
name: 'MyApp',
vectorYouNeed: {},
launch: function () { ...
Then add the key-value pairs to the object like this
MyApp.vectorYouNeed[key] = value;
And fetch them like this
value = MyApp.vectorYouNeed[key];
Note that key is a string object i.e. var key='key1'; and value can be any type of object.
To remove one value MyApp.vectorYouNeed[key] = null; And to remove all of them MyApp.vectorYouNeed = {};
I use as a front-end sproutcore, and as back-end an nhibernate driven openrasta REST solution.
In sproutcore, references are actualy ID's / guid's. So an Address entity in the Sproutcore model could be:
// sproutcore code
App.Address = App.Base.extend(
street: SC.Record.attr(String, { defaultValue: "" }),
houseNumber: SC.Record.attr(String),
city: SC.Record.toOne('Funda.City')
);
with test data:
Funda.Address.FIXTURES = [
{ guid: "1",
street: "MyHomeStreet",
houseNumber: "34",
city: "6"
}
]
Here you see that the reference city has a value of 6. When, at some point in your program, you want to use that reference, it is done by:
myAddress.Get("city").MyCityName
So, Sproutcore automatically uses the supplied ID in a REST Get, and retrieves the needed record. If the record is available in de local memory of the client (previously loaded), then no round trip is made to the server, otherwise a http get is done for that ID : "http://servername/city/6". Very nice.
Nhibernate (mapped using fluent-nhibernate):
public AddressMap()
{
Schema(Config.ConfigElement("nh_default_schema", "Funda"));
Not.LazyLoad();
//Cache.ReadWrite();
Id(x => x.guid).Unique().GeneratedBy.Identity();
Table("Address");
Map(x => x.street);
Map(x => x.houseNumber);
References(x => x.city,
"cityID").LazyLoad().ForeignKey("fk_Address_cityID_City_guid");
}
Here i specified the foreign key, and to map "cityID" on the database table. It works ok.
BUT (and these are my questions for the guru's):
You can specify to lazy load / eager load a reference (city). Off course you do not want to eager load all your references. SO generally your tied to lazy loading.
But when Openrast (or WCF or ...) serializes such an object, it iterates the properties, which causes all the get's of the properties to be fired, which causes all of the references to be lazy loaded.
SO if your entity has 5 references, 1 query for the base object, and 5 for the references will be done. You might better be off with eager loading then ....
This sucks... Or am i wrong?
As i showed how the model inside sproutcore works, i only want the ID's of the references. So i Don't want eagerloading, and also not lazy loading.
just a "Get * from Address where ID = %" and get that mapped to my Address entity.
THen i also have the ID's of the references which pleases Sproutcore and me (no loading of unneeded references). But.... can NHibernate map the ID's of the references only?
And can i later indicate nHibernate to fully load the reference?
One approach could be (but is not a nice one) to load all reference EAGER (with join) (what a waste of resources.. i know) and in my Sever-side Address entity:
// Note: NOT mapped as Datamember, is NOT serialized!
public virtual City city { get; set; }
Int32 _cityID;
[Datamember]
public virtual Int32 cityID
{
get
{
if (city != null)
return city .guid;
else
return _cityID;
}
set
{
if (city!= null && city.guid != value)
{
city= null;
_cityID = value;
}
else if (city == null)
{
_cityID = value;
}
}
}
So i get my ID property for Sproutcore, but on the downside all references are loaded.
A better idea for me???
nHibernate-to-linq
3a. I want to get my address without their references (but preferably with their id's)
Dao myDao = new Dao();
from p in myDao.All()
select p;
If cities are lazy loading in my mapping, how can i specify in the linq query that i want it also to include my city id only?
3b.
I want to get addresses with my cities loaded in 1 query: (which are mapped as lazyloaded)
Dao myDao = new Dao();
from p in myDao.All()
join p.city ???????
select p;
My Main Question:
As argued earlier, with lazy loading, all references are lazy loaded when serializing entities. How can I prevent this, and only get ID's of references in a more efficient way?
Thank you very much for reading, and hopefully you can help me and others with the same questions. Kind regards.
as a note you wrote you do this
myAddress.Get("city").MyCityName
when it should be
myAddress.get("city").get("MyCityName")
or
myAddress.getPath("city.MyCityName")
With that out of the way, I think your question is "How do I not load the city object until I want to?".
Assuming you are using datasources, you need to manage in your datasource when you request the city object. So in retrieveRecord in your datasource simply don't fire the request, and call dataSourceDidComplete with the appropriate arguments (look in the datasource.js file) so the city record is not in the BUSY state. You are basically telling the store the record was loaded, but you pass an empty hash, so the record has no data.
Of course the problem with this is at some point you will need to retrieve the record. You could define a global like App.WANTS_CITY and in retrieveRecords only do the retrieve when you want the city. You need to manage the value of that trigger; statecharts are a good place to do this.
Another part of your question was "How do I load a bunch of records at once, instead of one request for each record?"
Note on the datasource there is a method retrieveRecords. You can define your own implementation to this method, which would allow you to fetch any records you want -- that avoids N requests for N child records -- you can do them all in one request.
Finally, personally, I tend to write an API layer with methods like
getAddress
and
getCity
and invoke my API appropriately, when I actually want the objects. Part of this approach is I have a very light datasource -- I basically bail out of all the create/update/fetch methods depending on what my API layer handles. I use the pushRetrieve and related methods to update the store.
I do this because the store uses in datasources in a very rigid way. I like more flexibility; not all server APIs work in the same way.