The Datamapper documentation does a great job of telling me how to set up contextual lazy loading here but unfortunately it doesn't tell me how to actually pass the context in record retrievals.
I imagine it would be something like so:
id = 10
hotel = Hotel.get(id, :context => :detailed)
or something like that. Can someone please provide an example?
When a lazy property is read, all properties in the same context are loaded in the same query. There's no other ways to specify a context. Maybe you should patch Datamapper or write a feature request.
Related
I would like to know if there is an elegant way to add scoped properties to Application Insights, something similar to Serilog:
var yearEnricher = new PropertyEnricher("Year", year);
using (LogContext.PushProperties(yearEnricher))
{
// ...
}
In the previous example every log created within the using block will have the property Year stamped on it.
I figured out how to do this when I want the property to be present within the whole request pipeline:
var requestTelemetry = context.Features.Get<RequestTelemetry>();
requestTelemetry?.Properties.Add(propertyName, propertyValue.ToString());
Sometimes I want to create a logging scope in code that is not related to the web context so it doesn't make sense to rely on the IHttpContextAccessor. I acknowledge I could leverage OperationTelemetry and TelemetryClient.StartOperation to achieve my goal but it is cumbersome as I've to implement a few properties in which I've no interest (such as Name, Success, Duration...).
Is there a better way than relying on OperationTelemetry?
If you don't want to use OperationTelemetry, you might want to look into implementing your own ITelemetryInitializer (see documentation here).
It should be fairly easy to implement a stack-like global structure to hold the properties you want to push, and pop the stack on your Dispose method.
Note that you'll probably need to utilize CallContext in order for your stacks to be thread safe.
I am interested in loading some system params into the Yii::app()->params array from the database using a CActiveRecord extension called SiteSetting.
Unfortunately I couldn't find much advice online for this, but believe I can place a method in SiteSetting called loadSiteSettingsToAppParams and add the setting...
'onBeginRequest'=>array('SiteSetting', 'loadSiteSettingsToAppParams')
...to the config.
I would like to know if I can only add this onBeginRequest to the Yii::app() somewhere within the SiteSetting class (to keep my code modular) and whether this is a sensible approach.
Thanks in advance.
Just re-read your question now and I'd try to provide answers.
To the question "I would like to know if I can only add this onBeginRequest to the Yii::app() somewhere within the SiteSetting class (to keep my code modular)": the answer is, You're not restricted to just a Class. You could (theoretically) place it anywhere within your application and also in the config.php file.
As to whether it's a sensible approach, it depends on the time it would take to request those settings from the database and whether you're prepared to add that time to your HttpRequest response time. The onBeforeRequest is fired before every HttpRequest and if the loadSiteSettingsToAppParams method consumes lots of time, you're adding that time to your HttpRequest response time.
I'd advise that you fetch those settings once after login and then update them only when they change (the settings are updated). This way, you could place the call to loadSiteSettingsToAppParams in the UserIdentity class and call it after a successful login.
That's just how I'd go about doing this though.
Hope I helped.
The easy & nice way to accomplish this by using a comoponent like SettingComoponent and place in the components directory protected/components then pre load this component in the preload section like this preload => array('log', 'setting', ...). That's it and now you can call this component anywhere you want like Yii:app()->setting->whatever.
I hope this is answer can be useful for you.
I am creating a new web app and would like some help on design plans.
I have "store" objects, and each one has a number of "message" objects. I want to show a store page that shows this store's messages. Using Doctrine, I have mapped OneToMany using http://symfony.com/doc/current/book/doctrine.html
However, I want to show messages in reverse chronological order. So I added a:
* #ORM\OrderBy({"whenCreated" = "DESC"})
Still I am calling the "store" object, then calling
$store->getMessages();
Now I want to show messages that have been "verified". At this point, I am unsure how to do this using #ORM so I was thinking I need a custom Repository layer.
My question is twofold:
First, can I do this using the Entity #ORM framework?
And second, which is the correct way to wrap this database query?
I know I eventually want the SQL SELECT * FROM message WHERE verified=1 AND store_id=? ORDER BY myTime DESC but how to make this the "Symfony2 way"?
For part 1 of your question... technically I think you could do this, but I don't think you'd be able to do it in an efficient way, or a way that doesn't go against good practices (i.e. injecting the entity manager into your entity).
Your question is an interesting one, because at first glance, I would also think of using $store->getMessages(). But because of your custom criteria, I think you're better off using a custom repository class for Messages. You might then have methods like
$messageRepo->getForStoreOrderedBy($storeId, $orderBy)
and
$messageRepo->getForStoreWhereVerified($storeId).
Now, you could do this from the Store entity with methods like $store->getMessagesWhereVerified() but I think that you would be polluting the store entity, especially if you need more and more of these custom methods. I think by keeping them in a Message repository, you're separating your concerns in a cleaner fashion. Also, with the Message repository, you might save yourself a query by not needing to first fetch your Store object, since you would only need to query to Message table and use its store_id in your WHERE clause.
Hope this helps.
The code:
public ChatMessage[] GetAllMessages(int chatRoomId)
{
using (ChatModelContainer context = new ChatModelContainer(CS))
{
//var temp = context.ChatMessages.ToArray();
ChatRoom cr = context.ChatRooms.FirstOrDefault(c => c.Id == chatRoomId);
if (cr == null) return null;
return cr.ChatMessages.ToArray();
}
}
The problem:
The method (part of WCF-service) returns an empty array. If I uncomment the commented line it starts working as expected. I have tried turning of lazy loading but it didnt help.
Also, when it works, I get ChatMessages with a reference to ChatRoom populated but not the ChatParticipant. They are both referenced by the ChatMessage-entity in the schema with both Id and Navigation Properties. The Ids are set and points to the right entities but on the client-side only the ChatRoom-reference has been populated.
Related questions:
Is an array the preferred method to return collections of EF-entities like this?
When making a change in my model (edmx) Im required to run the "Generate Database from Model..."-option before I can run context.CreateDatabase(). Why? I get some error message pointing to old SSDL but I cant find where the SSDL is stored. Is this created when I run this "Generate Database..."-option?
Is it safe to return entire entity-graphs to the client? Ive read some about "circular reference exeptions" but is this fixed in EF4?
How and when is references populated in EF4? If I have lazy-loading turned on I suspect only entities I touch is populated? But with lazy loading turned off, should the entire graph be populated always then?
Are there any drawbacks of using self-updating entities over ordinary entities in EF4? I dont need self-updating right now but I might do later. Can I upgrade easily or should I start with self-updating from the start?
Why cant I use entity-keys with type string?
Each of your questions needs a separate answer, but I'll try to answer them as briefly as possible.
First of all, in the code sample you provided, you get a ChatRoom object and then try to access a related object that is not included in your query (ChatMessages). If lazy loading is turned off as you had suggested, then you will need the Include("ChatMessages") call in your query, so your LINQ query should look like this:
ChatRoom cr = context.ChatRooms.Include("ChatMessages").FirstOrDefault(c => c.Id == chatRoomId);
Please ensure that your connection string is in your config file as well.
For the related questions:
You can return collections in any way you choose - I have typically done them in a List object (and I think that's the common way), but you could use arrays if you want. To return as a list, use the .ToList() method call on your query.
I don't understand what you're trying to do here, are you using code to create your database from your EDMX file or something? I've typically used a database-first approach, so I create my tables etc then update my EDMX from the database. Even if you generate your DB from your model, you shouldn't have to run CreateDatabase in code, you should be able to run the generated script against your DB. If you are using code-only then you need to dump the EDMX file.
You can generally return entity graphs to the client, should handle ok.
EF4 should only populate what you need. If you use lazy loading, it will automatically load things that you do not include in your LINQ query when you reference them and execute the query (e.g. do a ToList() operation). This won't work so well if your client is across a physical boundary (eg a service boundary) obviously :) If you don't use lazy loading, it will load what you tell it to in your query and that is all.
Self tracking entities are used for n-tier apps, where objects have to be passed across physical boundaries (eg services). They come with an overhead of generated code for each object to keep track of its changes, they also generate POCO objects which are not dependent on EF4 (but obviously contain generated code that would make the tracked changes work with the EF4 tracker). I'd say it depends on your usage, if you're building a small app that's quite self contained, and don't really care about separation for testability without the infrastructure in place, then you don't need to use self tracking entities. I say only use framework features when you need them, so if you're not writing an enterprise scale application (enterprise doesn't have to be big, but something scalable, highly testable, high quality etc) then no need to go for self tracking POCOs.
I haven't tried but you should be able to do that - that would be a candidate for a separate question if you can't get it to work :)
I first apologize for my poor english level and maybe for the stupidity of my question ;)
I am on an alfresco project to learn how it works.
I have to browse programatically my content repository and gather datas all along. In order to do that I guessed I had to use a ContentReader (I get from my ContentService) but the method getReader wants a nodeRef and a propertyQualifiedName.
I am ok with the nodeRef, I get what it's needed for.
But the propertyQualifiedName puzzles me, I barely get what it is but I frankly don't get how it is used.
Reading some alfresco forum threads I get more and more scared that I dont even get how a reader works, I somewhere saw that a reader can read only one node and only one time per instance.
If anyone knows a bit about the Java API for Alfresco Content Repository use I am all hears !
Cheers all !
ContentReader is a wrapper class for the content of a given property of a node. So, in order to get an instance of ContentReader you'll have to give the node from which you the property from and the property qualified name.
As for the qualified name, every node property is identified by the conjunction of two string values:
The property namespace. Usually an uri like "http://www.alfresco.org/model/content/1.0"
The property local name. Usually a simple string like "created".
These two values put together constitute the property qualified name. There are constants defined for most standard properties of the alfresco model in the org.alfresco.model.ContentModel interface. For example, to get the creator of a node you would do something like:
contentService.getReader(myNode, ContentModel.PROP_CREATOR).getContentString();