As far as I can tell, relay relies on nodeDefitions for queries when variables are being changed.
It'd appear that all objects with an id field should be a valid node. However, if I have data like this:
type User {
id: globalIdField('User'),
name: String,
folders: [ Folder ]
}
type Folder {
id: ???,
...
}
The data is stored in a document based solution, and the Folder objects are nested in the User object. But Folder objects are given an id so that some other objects could reference the Folder objects under the context of a User.
If Folder implements the nodeInterface, and uses globalIdField, then I need to figure out a way to fetch the Folder object from a globalId, meaning that I might have to scan through all the Users to find it, have a data map that'd allow me to find the object, or normalize the data so that Folders are in their own table.
If it doesn't implement the nodeInterface, and just uses Strings as id field, what happens when I try to mutate some fields on the Folder object?
It's often useful for these objects to have ids, even if there's no real id directly in your database. For example, if you want to write a mutation to rename a folder, it'd be great to have a global ID to reference this folder. Relay also uses them internally when the UI requests some additional data on a node that's not loaded yet.
One way to generate a global ID for the folder could be to take a prefix and add the user id and a way to identify the folder within the user, for example:
var folderID = ['folder', userID, folderID].join(':');
Whenever you want to resolve this id on your server, you split at the :, see that you want to load a folder by looking at the first part and then go via user to the right folder.
Related
I am currently setting up my realtime firebase database to my iOS application.
It is my first time trying to structure user data in a firebase database, and I am really, really struggling with understanding a few key things.
A bit of context to my application's database needs:
When a new user is created, the attributes assigned directly to the user are:
Age
Email
Username
Nationality
Later on, the user needs the option of creating personal diaries!
Each of these diaries being arrays/lists of objects... Where each object in a diary furthermore holds a few attributes in a list/array.
After reading everything I could find anywhere, I picture my database something like this:
I am terribly sorry if it becomes too specific - I will try to make the question as open as possible:
My question is:
How to create the different "children" programmatically and how to find the keys leading back to them, so I can refer to them at other times again? (when editing an attribute in a child).
A few methods I have tried:
setValue([ArrayOfObjects]) --> This creates the desired array, but I can't seem to find e.g. index 3 in this array, to allow user to change his/her email later on.
childByAutoID() --> This as well creates my array, but gives several other problems: User can only store one diary, still can't find the paths to specific indexes...
setValue(), andPriority() --> Can't seem to make the priority function. (Is this function also outdated??)
And a few more...
If anyone can tell me how to achieve just the first few steps in setting up my database structure, I will be forever grateful - I have spent literally all day on it and I am not moving forward ...
Or, at least tell me, if I am on the right track regarding my desired setup of the database. Is it flat enough? Is there a smarter way to store all these user created lists?
Thank you so much! :-)
I don't know Swift so my examples are in Dart but the methods are similar I believe.
First off, I would split the Users node into two. One to hold the user data, which is normally pretty static, and the other to hold the diaries. You would use the same uid key as reference to both. This way you have less nesting to worry about and therefore it is much easier to CRUD the data. If you are using Firebase to authenticate your users then I would use the unique key that Firebase creates for each user as the keys for these two nodes.
Then...
To create a user data node record the Dart code would be something like:
referenceUserData.child(<authenticated user id>).set({
"age": <age value>,
"email": <email value>,
"name": <name value>,
});
To create a user diary node object record the Dart code would be something like:
referenceUserData.child(<authenticated user id>).child(<diary key>).child(<diary object key>).set({
"object info value 1": <object value>,
"object info value 2": <object value>,
"object info value 3": <object value>,
});
You could also create all the object records at once by writing them as a List (array) using .set().
You also need to decide what your diary key should be. You could use Firebase to generate a unique key by using .push().set().
To read eg. the user data then your call could be:
referenceUserData
.child(<authenticated user id>)
.once()
.then(
(DataSnapshot snapshot) {
print(snapshot.key);
if (snapshot.value != null) {
print(snapshot.value);
<code to process your snapshot value>
}
};
BTW, 'priority' is legacy from the early days of Firebase RTDB so I wouldn't try to use it.
In my previous question I was looking for a way to access and store return value of the function in qaf step. I was provided with the following:
When create new user using "{'name':'user1','password':'user123'}"
And store into 'newUser'
Then system should have user '${newUser}'
Now, I'd like to know how to get value from object/collection stored.
If it is a simple object named newUser which has field Id. How would I pass Id on next step?
And, if return is List, how to get by index from stored list?
Resolved issue on my own. If anyone faces same unknowns, here is how I solved it.
For requirements to work around response data, parsing same stored objects in properties by specific fields or collecting data from other structures such as Maps or Lists, create common functions with #QAFTestStep annotation to get data for class member name, map by key or list by index and so on... Add those in common steps and then write stepname text in gherkin format with parameters specified. Let me know if someone needs help, always ready to help out...
We're in the process of moving to DTM implementation. We have several variables that are being defined on page. I understand I can make these variables available in DTM through data elements. Can I simply set up a data elem
So set data elements
%prop1% = s.prop1
%prop2% = s.prop2
etc
And then under global rules set
s.prop1 = %s.prop1%
s.prop2 = %s.prop2%
etc
for every single evar, sprop, event, product so they populate whenever they are set on a particular page. Good idea or terrible idea? It seems like a pretty bulky approach which raises some alarm bells. Another option would be to write something that pushes everything to the datalayer, but that seems like essentially the same approach with a redundant step when they can be grabbed directly.
Basically I want DTM to access any and all variables that are currently being set with on-page code, and my understanding is that in order to do that they must be stored in a data element first. Does anyone have any insight into this?
I use this spec for setting up data layers: Data Layer Standard
We create data elements for each key that we use from the standard data layer. For example, page name is stored here
digitalData.page.pageInfo.pageName
We create a data element and standardize the names to this format "page.pageInfo.pageName"
Within each variable field, you access it with the %page.pageInfo.pageName% notation. Also, within javascript of rule tags, you can use this:
_satellite.getVar('page.pageInfo.pageName')
It's a bit unwieldy at times but it allows you to separate the development of the data layer and tag manager tags completely.
One thing to note, make sure your data layer is complete and loaded before you call the satellite library.
If you are moving from a legacy s_code implementation to DTM, it is a good best practice to remove all existing "on page" code (including the reference to the s_code file) and create a "data layer" that contains the data from the eVars and props on the page. Then DTM can reference the object on the page and you can create data elements that map to variables.
Here's an example of a data layer:
<script type="text/javascript">
DDO = {} // Data Layer Object Created
DDO.specVersion = "1.0";
DDO.pageData = {
"pageName":"My Page Name",
"pageSiteSection":"Home",
"pageType":"Section Front",
"pageHier":"DTM Test|Home|Section Front"
},
DDO.siteData = {
"siteCountry":"us",
"siteRegion":"unknown",
"siteLanguage":"en",
"siteFormat":"Desktop"
}
</script>
The next step would be to create data elements that directly reference the values in the object. For example, if I wanted to create a data element that mapped to the page name element in my data layer I would do the following in DTM:
Create a new data element called "pageName"
Select the type as "JS Object"
In the path field I will reference the path to the page name in my data layer example above - DDO.pageData.pageName
Save the data element
Now this data element can be referenced in any variable field within any rule by simply typing a '%'. DTM will find any existing data elements and you can select them.
I also wrote about a simple script you can add to your implementation to help with your data layer validation.Validate your DTM Data Layer with this simple script
Hope this helps.
I would like to separate my reference data from my user data in my Core Data model to simplify future updates of my app (and because, I plan to store the database on the cloud and there is no need to store reference data on the cloud as this is part of my application). Therefore, I've been looking for a while for a way to code a cross-store relationship using fetched properties. I have not found any example implementations of this.
I have a Core Data model using 2 configurations :
data model config 1 : UserData (entities relative to user)
data model config 2 : ReferenceData (entities relative to application itself)
I set up 2 different SQLite persistent stores for both config.
UserData config (and store) contains entity "User"
ReferenceData config (and store) contains entities "Type" and "Item".
I would like to create two single-way weak relationships as below :
A "User" has a unique "Type"
A "User" has many "Items"
Here are my questions :
How do I set up my properties?
Do I need 2 properties for each relation (one for storing Unique ID and another to access my fetched results)?
Could this weak relationship be ordered?
Could someone give me an example implementation of this?
As a follow-on to Marcus' answer:
Looking through the forums and docs, I read that I should use the URI Representation of my entity instance instead of objectID. What is the reason behind this?
// Get the URI of my object to reference
NSURL * uriObjectB [[myObjectB objectID] URIRepresentation];
Next, I wonder, how do I store my object B URI (NSURL) in my parent object A as a weak relationship? What attribute type should I use? How do I convert this? I heard about archive... ?
Then, later I should retrieve the managed object the same way (by unconvert/unarchive the URIRepresentation) and get Object from URI
// Get the Object ID from the URI
NSManagedObjectID* idObjectB = [storeCoordinator managedObjectIDForURIRepresentation:[[myManagedObject objectID] URIRepresentation]];
// Get the Managed Object for the idOjectB ...
And last but not least, shouId I declare two properties in my entity A, one for persisting of URI needs and another for retrieving direclty object B?
NSURL * uriObjectB [objectA uriObjectB];
ObjectB * myObjectB = [objectA objectB];
As you can read, I really miss some simple example to implement thes weak relationships ! I would really appreciate some help.
Splitting the data is the right answer by far. Reference data should not be synced with the cloud, especially since iCloud has soft caps on what it will allow an application to sync and store in documents.
To create soft references across to stores (they do not need to be SQLite but it is a good idea for general app performance) you will need to have some kind of unique key that can be referenced from the other side; a good old fashioned foreign key.
From there you can create a fetched property in the model to reference the entity.
While this relationship cannot be ordered directly you can create order via a sort index or if it has a logical sort then you can sort it once you retrieve the data (I use convenience methods for this that return a sorted array instead of a set).
I can build up an example but you really are on the right track. The only fun part is migration. When you detect a migration situation you will need to migrate each store independently before you build up your core data stack. It sounds tricky but it really is not that hard to accomplish.
Example
Imagine you have a UserBar entity in the user store and a RefBar entity in the reference store. The RefBar will then have a fetchedProperty "relationship" with a UserBar thereby creating a ToOne relationship.
UserBar
----------
refBarID : NSInteger
RefBar
--------
identifier : NSInteger
You can then create a fetched property on the RefBar entity in the modeler with a predicate of:
$FETCHED_PROPERTY.refBarID == identifier
Lets name that predicate "userBarFetched"
Now that will return an array so we want to add a convenience method to the RefBar
#class UserBar;
#interface RefBar : NSManagedObject
- (UserBar*)userBar;
#end
#implementation RefBar
- (UserBar*)userBar
{
NSArray *fetched = [self valueForKey:#"userBarFetched"];
return [fetched lastObject];
}
#end
To create a ToMany is the same except your convenience method would return an array and you would sort the array before returning it.
As Heath Borders mentioned, it is possible to add a sort to the NSFetchedProperty if you want but you must do it in code. Personally I have always found it wasteful and don't use that feature. It might be more useful if I could set the sort in the modeler.
Using the ObjectID
I do not recommend using the ObjectID or the URIRepresentation. The ObjectID (and therefore the URIRepresentation of that ObjectID) can and will change. Whenever you migrate a database that value will change. You are far better off creating a non-changing GUID.
The weak relationship
You only need a single value on the M side of the relationship and that stores the foreign identifier. In your object subclass you only need to implement accessors that retrieve the object (or objects).
I would go with just one store.
For storing stuff in the cloud, you will anyway have to serialize the data, either as JSON or SQL statements, or whatever scheme you prefer.
You will need a local copy of the data on the user's device, so he can access it quickly and offline. The cloud store can have only the user entity, while the local store (part of the app) can also have the reference entity.
I have a similar project with a huge reference store (20000 records) with geographic information, and user generated content ("posts"). I use a single store. When I ship the app, the "posts" entity is also defined but empty. When I update the data model I simply re-generate the whole reference store before shipping.
I see absolutely no reason to go for a cross store solution here.
I am still mostly unfamiliar with Inversion of Control (although I am learning about it now) so if that is the solution to my question, just let me know and I'll get back to learning about it.
I have a pair of controllers which need to a Session variable, naturally nothing too special has happen because of how Session works in the first place, but this got me wondering what the cleanest way to share related objects between two separate controllers is. In my specific scenario I have an UploadController and a ProductController which work in conjunction with one another to upload image files. As files are uploaded by the UploadController, data about the upload is stored in the Session. After this happens I need to access that Session data in the ProductController. If I create a get/set property for the Session variable containing my upload information in both controllers I'll be able to access that data, but at the same time I'll be violating all sorts of DRY, not to mention creating a, at best, confusing design where an object is shared and modified by two completely disconnected objects.
What do you suggest?
Exact Context:
A file upload View posts a file to UploadController.ImageWithpreview(), which then reads in the posted file and copies it to a temporary directory. After saving the file, another class produces a thumbnail of the uploaded image. The path to both the original file and the generated thumbnail are then returned with a JsonResult to a javascript callback which updates some dynamic content in a form on the page which can be "Saved" or "Cancelled". Whether the uploaded image is saved or it is skipped, I need to either move or delete both it and the generated thumbnail from the temporary directory. To facilitate this, UploadController keeps track of all of the upload files and their thumbnails in a Session-maintained Queue object.
Back in the View: after the form is populated with a generated thumbnail of the image that was uploaded, the form posts back to the ProductsController where the selected file is identified (currently I store the filename in a Hidden field, which I realize is a horrible vulnerability), and then copied out of the temp directory to a permanent location. Ideally, I would like to simply access the Queue I have stored in the Session so that the form does not need to contain the image location as it does now. This is how I have envisioned my solution, but I'll eagerly listen to any comments or criticisms.
A couple of solutions come to mind. You could use a "SessionState" class that maps into the request and gets/sets the info as such (I'm doing this from memory so this is unlikely to compile and is meant to convey the point):
internal class SessionState
{
string ImageName
{
get { return HttpContext.Current.Session["ImageName"]; }
set { HttpContext.Current.Session["ImageName"] = value; }
}
}
And then from the controller, do something like:
var sessionState = new SessionState();
sessionState.ImageName = "xyz";
/* Or */
var imageName = sessionState.ImageName;
Alternatively, you could create a controller extension method:
public static class SessionControllerExtensions
{
public static string GetImageName(this IController controller)
{
return HttpContext.Current.Session["ImageName"];
}
public static string SetImageName(this IController controller, string imageName)
{
HttpContext.Current.Session["ImageName"] = imageName;
}
}
Then from the controller:
this.SetImageName("xyz");
/* or */
var imageName = this.GetImageName();
This is certainly DRY. That said, I don't particularly like either of these solutions as I prefer to store as little data, if any, in session. But if you're intent is to hold onto all of this information without having to load/discern it from some other source, this is the quickest (dirtiest) way I can think of to do it. I'm quite certain there's a much more elegant solution, but I don't have all of the information about what it is you're trying to do and what the problem domain is.
Keep in mind that when storing information in the session, you will have to dehydrate/rehydrate the objects via serialization and you may not be getting the performance you think you are from doing it this way.
Hope this helps.
EDIT: In response to additional information
Not sure on where you're looking to deploy this, but processing images "real-time" is a sure fire way to be hit with a DoS attack. My suggestion to you is as follows -- this is assuming that this is public facing and anyone can upload an image:
1) Allow the user to upload an image. This image goes into the processing queue for background processing by the application or some service. Additionally, the name of the image goes into the user's personal processing queue -- likely a table in the database. Information about background processing in a web app can be found # Schedule a job in hosted web server
2) Process these images and, while processing, display a "processing graphic". You can have an ajax request on the product page that checks for images being processed and trys to reload them every X seconds.
3) While an image is being "processed", the user can opt out of processing assuming they're the one that uploaded the image. This is available either on the product page(s) that display the image or on a separate "user queue" view that will allow them to remove the image from consideration.
So, you end up with some more domain objects and those objects are managed by the queue. I'm a strong advocate of convention over configuration so the final destination of the product image(s) should be predefined. Something like:
images/products/{id}.jpg or, if a collection, images/products/{id}/{sequence}.jpg.
You then don't need to know the destination in the form. It's the same for all images.
The queue then needs to know where the temp image was uploaded and what the product id was. The queue worker pops items from the queue, processes them, and stores them accordingly.
I know this sounds a little more "structured" than what you originally intended, but I think it's a little cleaner.
Is there complete equivalence between the UploadController and ProductController?
As files are uploaded by the UploadController, data about the upload is stored in the Session. After this happens I need to access that Session data in the ProductController.
As I read that the UploadControl needs read and write access to Upload data, the ProductController needs only read.
If that's true then you can make it clear by using an immuatable wrapper around the upload information and have the UploadController put that into the session.
The Session itself is by definiton a public shared noticeboard, decouples explicit relationships at the cost of allowing anyone to get and put. You could allow the ProductController to know about the UploadController and hence remove the need for passing the upload information via the session. My instinct is that the upload info is interesting to the public, so using Session is reasonable.
I don't see any DRY violation here, we are explicitly trying to separate responsibilities.