Can any one please explain me what are all the best scenario to use particular dataprovider.
For ex :
When to use CActiveDataProvider ? (pros and cons)
When to use CArrayDataProvider ? (pros and cons)
When to use CSqlDataProvider ? (pros and cons)
CActiveDataProvider - Use this if you have a list of models (uses findAll()).
CArrayDataProvider - Use this when you have a raw array of objects which is not a list of models.
CSqlDataProvider - Use this when you have a database query resulting in a list of objects and not a list of models.
You can use all three of them to construct html with for example the (default) widgets.
The docs are quite clear on when and how to use the three:
CActiveDataProvider
CArrayDataProvider
CSqlDataProvider
Related
I need to call a collection consisting of objects that have an un-empty array in the items (array) field, I filter collection like this:
filter:
conditions:[
{
property: "items",
operator: "notEmpty",
value:null
}]
but this solution doesn't work, 500 error is returned, how to implement it?
CUBA Platform REST API doesn't support filtration by collections (#OneToMany and #ManyToMany relations).
To implement such functionality you need to create and expose predefined JPQL query on back end.
There is similar discussion on CUBA Platform forum.
I am using odata v5.7.0 for webapi(vb.net).I need all the properties of object should be expanded without using $expand property on the query string.
Ex: http://localhost:26209/ProductList?$expand=customers/products
into
http://localhost:26209/ProductList
Not sure why you would want to do that and there might not be a clear cut way to achive it.Still if you want to get all the products for a customer you will have to go one at a time by using something like this.
http://localhost:26209/ProductList/customers('customer_id')/products
Else if you are using OData 2 there is an EntitySet for every association, so you an directly query the products EntitySet and use $filter instead. The URL will look similar to
http://localhost:26209/Products?$filter=CustomerId eq *
You can check $filter conventions here
I would like to override the default lazy loading behavior which is set in mappings as 'lazy=false'. Can't change it as many parts of existing application depend on this setting.
After spent some hours on it I didn't find a solution so I'm asking here.
How to do this?
What I want to achieve is to fine tune my query to load only what is needed.
This is what I've tried already:
Using QueryOver api:
var properties = session.QueryOver<Property>()
.Fetch(prop => prop.Transactions).Eager
.Fetch(prop => prop.Districts).Eager
//I dont want to load those entities below so I mark
//them as lazy - IT DOESN'T WORK
//I can see in SQL that they are getting loaded in separate queries
.Fetch(prop => prop.Districts.First().Aliases).Lazy
.Fetch(prop => prop.Districts.First().PolygonPoints).Lazy
.Skip(i * pageSize)
.Take(pageSize)
.List();
Using Criteria api:
var criteria = session.CreateCriteria<Property>();
criteria.SetFetchMode("Transactions", NHibernate.FetchMode.Join);
criteria.SetFetchMode("Districts", NHibernate.FetchMode.Join);
criteria.SetFetchMode("Districts.Aliases", NHibernate.FetchMode.Select); // tried Lazy too
criteria.SetFetchMode("Districts.PolygonPoints", NHibernate.FetchMode.Select); // tried Lazy too
criteria.AddOrder(NHibernate.Criterion.Order.Asc("Id"));
criteria.SetFirstResult(i * pageSize);
criteria.SetMaxResults(pageSize);
var properties = criteria.List<Property>();
Using any of the above methods 'Aliases' and 'PolygonPoints' are always being loaded when calling List<>(). I don't need them in my process.
I'm using Nhibernate 4.0.
Any ideas?
We cannot override mapping in this case. We can do it opposite way - have lazy in place - and use eager fetching for querying.
The decision process (of reference loading) is done outside of the query, ex post. So it could be pre-loaded, but cannot be avoided.
Solution here could be of two types.
The first is preferred (by me) - do your best and make laziness the default: Ayende -
NHibernate is lazy, just live with it
Use projections. Instruct NHibernate to create just one query, use transformer to get expected object graph - without any proxies in it
There is pretty clear example how to (properly) use projection list even for references:
Fluent NHibernate - ProjectionList - ICriteria is returning null values
And we would also need Custom result transformer, which will ex-post create all the references from the returned data:
Custom DeepResultTransfomer
I am a new to using Mongo DB and exploring the frameworks around for migrating from mysql to mongodb. So far from my findings I have been able to figure out SpringMongo as the best solution to my requirements.
The only problem is that instead of using a DSL based or abstract querying mechanism, I wished the framework allowed me to pass plain json string as arguments to the different methods exposed by the API(find, findOne) so that the query parameters can be written out to an external file (using a key to refer) and passed to the methods by reading and parsing at run time. But the framework should be capable of mapping the results to the domain objects.
Is there a way in spring-mongo to achieve this? Or is there any other frameworks on the same lines
You could use Spring Data to do that, just use the BasicQuery class instead of Query class. Your code will look like the following:
/* Any arbitrary string that could to parsed to DBObject */
Query q = new BasicQuery("{ filter : true }");
List<Entity> entities = this.template.find(q, Entity.class);
If you want more details:
http://static.springsource.org/spring-data/data-mongo/docs/current/reference/html/#mongo.query
http://static.springsource.org/spring-data/data-mongodb/docs/current/api/org/springframework/data/mongodb/core/query/BasicQuery.html
Well I got to find this one in the Spring data MongoOperations...
String jsonCommand = "{username: 'mickey'}";
MongoOperations mongoOps = //get mongooperations implemantation
mongoOps.executeCommand(jsonCommand)
It returns an instance of CommandResult that encapsulates the result.
I've just checked the man page of CDbCriteria, but there is not enough info about it.
This property is available since v1.1.7 and I couldn't find any help for it.
Is it for dynamically changing Model->scopes "on-the-fly"?
Scopes are an easy way to create simple filters by default. With a scope you can sort your results by specific columns automatically, limit the results, apply conditions, etc. In the links provided by #ldg there's a big example of how cool they are:
$posts=Post::model()->published()->recently()->findAll();
Somebody is retrieving all the recently published posts in one single line. They are easier to maintain than inline conditions (for example Post::model()->findAll('status=1')) and are encapsulated inside each model, which means big transparency and ease of use.
Plus, you can create your own parameter based scopes like this:
public function last($amount)
{
$this->getDbCriteria()->mergeWith(array(
'order' => 't.create_time DESC',
'limit' => $amount,
));
return $this;
}
Adding something like this into a Model will let you choose the amount of objects you want to retrieve from the database (sorted by its create time).
By returning the object itself you allow method chaining.
Here's an example:
$last3posts=Post::model()->last(3)->findAll();
Gets the last 3 items. Of course you can expand the example to almost any property in the database. Cheers
Yes, scopes can be used to change the attributes of CDbCriteria with pre-built conditions and can also be passed parameters. Before 1.1.7 you could use them in a model() query and can be chained together. See:
http://www.yiiframework.com/doc/guide/1.1/en/database.ar#named-scopes
Since 1.1.7, you can also use scopes as a CDbCriteria property.
See: http://www.yiiframework.com/doc/guide/1.1/en/database.arr#relational-query-with-named-scopes