im trying to figure out a good data model approach when using parse (underlying mongodb) for users that are allowed to select a tag and provide a value to them, lets call it just a rating since thats the easiest to understand.
Im working on a class that is called user tags that has the following structure currently in its collection.
User (pointer to user class)
Object (pointer to object to tag)
Tags (array of tags with values)
The tags can be up to maybe 30 tags and each one of them can have a rating of 1-5 in this case...
I was wondering if I could do a PFRelationship in an array that has the objectId of the tag as the key and value as the 1 - 5 rating.. here is an example json object mocked up to what im saying.
{
"3q24afadfadf": 3.5 //parse relation object id : value,
"234rrdfadfk": 2.4 //parse relation object id : value,
"as4q2w34lsdf": 2.3 //parse relation object id : value
}
This way I can store one row for the item that the user tagged and all the tags with its rating value along with that.
I'm not sure this is the right way or if its scalable when doing queries for get me all users items he or she tagged, along with the tag (name) and the values).
I also on top of that need to figure out a way to when many users tag the same item with different values that I build up some analytics or maybe counter class that gets incremented or averaged in to then be displayed along with the item. I might try cloudcode to do saveafter to update the analytic data class for that item.
Anyhow Any thoughts on this model would be appreciated and most importantly need to be able to get at the data inside the tag array, with hopefully the key being a pointer, if not a pointer i'm up to suggestions because the result should return
Item A
Tag name 1 with value 4.5
Tag Name 2 with value 3.5
and so on..
...
Also if you have any pointers to how to build aggregated data of the item and its over all value that many users have tagged over time.. My thought as above is to have a analytic class that the cloud code increments or that the app then increments, the challenge is to load all the user tags of item x, and get the tag and value out of the array and then add them to the analytic class. I could run this at night since it doesn't have to be real time.
Related
I have 100.000 images, each of them have 500 orb vectors, and each image has a unique tag.
My general issue is, when I insert a new image (i.e. 500 new vectors), how can I know if the image's tag is already in the database ?
What I do is to attache to each vector a metadata "tag". In can retrieve the inserted tags with
result = client.query.get('orb_vector', ['tag'])\
.with_limit(200)\
.do()
This provides more or less 200 tags among the 100.000 existing.
Accordingly to the documentation, that way of doing is not scalable.
How do I do ?
Context:
My database is not very dynamic; apart of the initial big insertion (100.000+ images), there will be few insertions each day. So I'm okay with a request taking 5 minutes and keeping the result in memory in a non-dynamic way. Plain python list is okay.
Clarification: each image has one tag, but 500 vectors. So each tag is present 500 times in the database.
I'm using python.
What I can do:
Writing the list of tags in a json/mongo/other and reading/updating it each time I insert new images.
I prefer to avoid this solution since the synchronization between the weaviate database and the json will just be a nightmare.
Have you considered creating a separate class for the tags and using query filters?
For example, define a schema for a class named Tag where:
it has a property called "name" to store the tag's name e.g. outdoors, indoors, etc
it has a property called "images" to store the cross references to the images that are tagged with "outdoors".
Then, when you want to insert an image with tag "car", for example, you do a WHERE filter on the Tag class where the name name is Equal to "car".
If the result is empty, then that tag does not exist.
I am pretty new to both Swift and Firebase, and I am attempting to make a simple app using Firebase as the backend. As far as I know, there is no memory-efficient way to use the numChildren() function without loading every single child into memory for counting, so I am implementing my own simple counter for the number of "Events" that have been created in my app.
The documentation for Firebase states that the childByAutoID() method should be used for updating lists in multi-user applications. I am assuming it adds a timestamp to the requested update and does them in order.
My question is whether it is necessary to use childByAutoID() when only updating a SINGLE field in a multi-user application. That is, will there be conflicts on my numEvents field if I do:
dbRef = FIRDatabase.database().reference()
dbRef.child("numEvents").setValue(num)
Or must I do:
dbRef = FIRDatabase.database().reference()
dbRef.child("numEvents").childByAutoId().setValue(num)
In order to avoid write conflicts? My only real confusion is that the documentation for childByAutoID stresses that it is useful when the children are a list of items, but mine is only a single item.
If you are only updating a single field you should not be using childByAutoId. To update a child value for an object, you need to obtain a reference to that object somehow, perhaps by a query of some sort (in many cases you will naturally already have a reference to the object if it needs to be changed) and you can change the value like this:
dbRef.child("events").child(objectToUpdateId).child(fieldToUpdateKey).setValue(newValue)
childByAutoId in this context would be used to create a new field like:
dbRef.child("events").childByAutoId().setValue(newObject)
I'm not exactly sure how this applies to your situation, but those are some descriptions of how to update a field, and use childByAutoId.
What childByAutoId does is create a unique key for a node, to avoid using the same key multiple times and then creating data conflicts like inconsistency (not write conflicts) to avoid write conflicts you use the transaction blocks.
The best way to learn is to try it out
If num == 1 , in the first example the result will be
dbRef:{
numEvents:1
}
While the second will be
dbRef:{
numEvents:{
//The auto-generated key
KLBHJBjhbjJBJHB:1
}
}
The childByAutoId would be useful if you want to save in a node multiple children of the same type, that way each children will have its own unique identifier
For example
pet:{
KJHBJJHB:{
name:fluffy,
owner:John Smith,
},
KhBHJBJjJ:{
name:fluffy,
owner:Jane Foster,
}
}
This way you have a unique identifier for cases where there is no clear way with the item data to guarantee it will be unique (in this case the pet's name)
Few things here:
childByAutoId is not a timestamp. But is used to create unique nodes in any given node.
Use case of childByAutoId :
You have messages node which stores messages from multiple user who are involved in a group chat. So each user can add messages in the group chat so you would do something like this each time user sends message:
dbRef = FIRDatabase.database().reference()
dbRef.child("messages").childByAutoId().setValue(messageText)
So this will create a unique message id for each message from different users. This will kind of act like primary key of message in normal databases.
The structure of database will be something like this:
messages: {
"randomIdGenerated-12asd12" : "hello",
"randomIdGenerated-12323D123" : "Hi, HOw are you",
}
So in your case your first approach is good enough! Since you dont need unique node for counting number of events added.
So, my Swift app allows a user to choose sports teams to see historic match information for. Currently, a user selects team(s) and the JSON data file of historic matches is scanned.
If a historic match includes a name of a selected team, the details of the match are stored in a Core Data entity, which is fed into my main Table View.
However, this presents an issue I can't get my head around solving.
If a user selects team A and B, and the database contains a match where team A and B played EACH OTHER, two objects for the match details are created, and as such, Table View cell is created twice, once for team A being found in the instance of the match, and again for team B.
Is there an easy and efficient way to trim any duplicates caused in this way? I don't know whether to handle this at the object creation time, or just to find a way of removing any duplicated cells from my Table View.
Thanks so much.
I think you should redesign your setup. Have all the records to be searched stored in Core Data.
If you have a hardcoded JSON file - import it on first start. If you have retrieved JSON - insert / update the elements that are new / changed in your Core Data object graph.
You would have a Match or Game entity and it would be retrieved only once. The fetch predicate would be something like
NSPredicate(format: "homeTeam = %# || guestTeam = %#", selectedTeam, selectedTeam)
I am trying to create nested FB Graph API request to get images for public event.
The full JSON object is given at this gist: https://gist.github.com/ZeKoU/be92b88440a6ca3d6be3
What I am trying to do is to get only data.0.images object, i.e. I want to get first object from data , then to get images array, and then to pick some fields from there (source for example).
However, all my attempts (see picture below) are returning only two fields for each object inside data field.
Not sure what you're trying to do, but from what I understood the query
/310897782446456?fields=photos.fields(id,images{source}).limit(1)
should be an example of getting the first photo, extract only some fields from the object (id and images for example), and then get a single field (source for example) from the images array's objects.
https://developers.facebook.com/tools/explorer?method=GET&path=310897782446456%3Ffields%3Dphotos.fields(id%2Cimages%7Bsource%7D).limit(1)&version=v2.3
See
https://developers.facebook.com/docs/graph-api/using-graph-api/v2.3#fieldexpansion
I am trying to store metadata (basically a unique id) along with each cell of a table in a Word document. Currently, for the add-in I'm developing, I am querying the database, and building a table inside the Word document using the data that is retrieved.
I want to be able to save any of the user's edits to the document, and persist it back to the database. My initial thought was to store a unique id along with each cell in the table so that I would be able to tell which records to update. I would also like to store some sort of "isChanged" flag within each cell so that I could tell which cells were changed. I found that I could add the needed information into the "ID" property of the cell - however, that information was not retained if the user saved the document, closed it, and re-opened it. I then tried storing the data by adding a data to the "Fields" collection - but that did not work and threw a runtime error. Here is the code that I tried:
object t1 = Word.WdFieldType.wdFieldEmpty;
object val = "myValue: " + counter;
object preserveFormatting = true;
tbl.Cell(i, j).Range.Fields.Add(tbl.Cell(i, j).Range, ref t1, ref val, ref preserveFormatting);
This compiles fine, but throws this runtime error "This command is not available".
So, is this possible at all? Or am I headed in the wrong direction?
Thanks in advance.
Wound up using "ContentControls" to store the information I needed. I used the "Title" field to store the unique id, and the "tag" field to track whether the field had been changed or not. See this link for more info: http://blogs.technet.com/gray_knowlton/archive/2010/01/15/associating-data-with-content-controls.aspx
Since a "Word 2007 Document" is XML, you can add a namespace to the document then adore the elements with attributes from your namespace. Word should ignore your namespace when loading and saving. Moreover, you can add new elments to store any information (metadata) needed.
With that said, I have not used this technique with Word, but I have done it successfully using Excel 2003.
First thing to try, is create a bare "Word 2007 Document". In your case, add a simple two by two table. Open it with a text or XML editor and add your namespace, and adore an attribute and add an element. Open with Word make a change then save it. Open with editor and make sure your namespace attribute and element have not been changed.