I insert/update my Realm database like this:
Realm.getDefaultInstance().use {
realmInstance -> realmInstance.executeTransaction {
realm -> realm.insertOrUpdate(data)
}
}
But this puts newly added data at the end of the table content. How can I put the data at the beginning?
Respone from API:
Latest item
Other items
Scenerio A: This is the first time I receive items from API. I insert them in database in the same exact order.
After a while, I've to send the latest item from my local storage. Usually this would be the last item in local database, but as the list is in reverse order from API, I've to send the first item (you can see order of list). Well. After some while I get a new data from API. We insert in database. From this moment, the latest item will be always the last one in database. I could avoid this mess if I just always knew, that the latest item would be the very first item. It would work for both cases.
Related
I am working on my cron system which gathers informaiton via an API call. For most, it has been fairly straight forward, but now I am faced with multiple difficulties, as the API call is dependant on who is making the API request. It runs through each users API Key and certain information will be visible/hidden to them and visaversa to the public.
There are teams, and users are part of teams. A user can stealth their move, however all information will be showed to them and their team, however this will not be visible to their oponent, however both teams share the same id and have access tothe same informaiton, just one can see more of it than the other.
Defendants Point Of View
"attacks": {
"12345`": {
"timestamp": 1645345234,
"attacker_id": "",
"attacker_team_id": "",
"defender_id": 321,
"defender_team_id": 1,
"stealthed": 1
}
}
Attackers Point Of View
"attacks": {
"12345`": {
"timestamp": 1645345234,
"attacker_id": 123,
"attacker_team_id": 2
"defender_id": 321,
"defender_team_id": 1,
"stealthed": 1,
"boosters": {
"fair_fight": 3,
"retaliation": 1,
"group_attack": 1
}
}
}
So, if the defendant's API key is first used, id 12345 will already be in the team_attacks table but will not include the attacker_id and attacker_team_id. For each insert there after, I need to check to see whether the new insert's ID already exist and has any additional information to add to the row.
Here is the part of my code that loops through the API and obtains the data, it loops through all the attacks per API Key;
else if ($category === "attacks") {
$database = new Database();
foreach($data as $attack_id => $info) {
$database->query('INSERT INTO team_attacks (attack_id, attacker_id, attacker_team_id, defender_id, defender_team_id) VALUES (:attack_id, :attacker_id, :attacker_team_id, :defender_id, :defender_team_id)');
$database->bind(':attack_id', $attack_id);
$database->bind(':attacker_id', $info["attacker_id"]);
$database->bind(':attacker_team_id', $info["attacker_team_id"]);
$database->bind(':defender_id', $info["defender_id"]);
$database->bind(':defender_team_id', $info["defender_team_id"]);
$database->execute();
}
}
I have also been submitting to the news table, and typically I have simply been submitting X new entries have been added or whatnot, however I haven't a clue if there is a way to check during the above if any new entries and any updated entries to produce two news feeds:
2 attacks have bee updated.
49 new attack information added.
For this part, I was simply counting how many is in the array, but this only works for the first ever upload, I know I cannot simply count the array length on future inserts which require additional checks.
If The attack_id Does NOT Already Exist I also need to submit the boosters into another table, for this I was adding them to an array during the above loop and then looping through them to submit those, but this also depends on the above, not simply attempting to upload for each one without any checks. Boosters will share the attack_id.
With over 1,000 teams who will potentially have at least one members join my site, I need to be as efficient as this as possible. The API will give the last 100 attacks per call and I want this to be within my cron which collects any new data every 30 seconds, so I need to sort through potentially 100,000.
In SQL, you can check conditions when inserting new data using merge:
https://en.wikipedia.org/wiki/Merge_(SQL)
Depending on the database you are using, the name and syntax of the command might be different. Common names for the command are also upsert and replace.
But: If you are seeking for high performance and almost-realtimeness, consider using a cache holding critical aggregated data instead of doing the aggregation 100'000 times per minute.
This may or may not be the "answer" you're looking for. The question(s) imply use of a single table for both teams. It's worth considering one table per team for writes to avoid write contention altogether. The two data sets could be combined at query time in order to return "team" results via the API. At scale, you could have another process calculating and storing combined team results in an API-specific cache table that serves the API request.
Deleting an item from a collection, which has a status field, through the UI or API results in the item being soft deleted. However, in this one particular instance, we want to remove it from the database entirely.
If not possible, can it safely be done through the database by just deleting it from the table carrying the name of the collection? Any side-effects when doing it this way?
Found the answer on this page https://v8.docs.directus.io/guides/status.html#soft-delete:
When deleting an item, the API does the following:
Check if the collection has a status field
Check if the delta data has the status field (meaning the status was changed)
Check if the new status value (from delta data) has soft_delete = true
If yes, it sets the action to SOFT_DELETE
If no, it hard deletes the item (permanently removed from the database)
I am attempting to make a database that stores user information on the device. I am using flutter combined with sqlflite. I want to always store the data of the current user in row one of the SQL database. Is there anyway to do that with the .insert method?
int id = await db.insert(
'user',
user.toMap(),
conflictAlgorithm: ConflictAlgorithm.replace,
);
This is the code I am using for inserting, but when the user changes the screen name or email, it will put the user now into the second row.
After a long period of research, I came to discover that the issue was not in my SQL code, it was instead in my use of the code. The object was returning a list of all objects and I was thinking it was returning one object.
I need to quickly check to see if I have some duplicate values in CoreData. I am doing some background syncing and occasionally a dupe makes it into my system.
I have a ManufacturerID and an ItemID and I cannot have a duplicate value for both, example of bad data:
ManufacturerID ItemID
35 IT001
35 IT001
So I would just want to know if that happened and maybe get a list of those ItemID's, then I need a way to figure out how to get rid of the dupes but this is a good start.
I just need a fast method figure out if they exist or not.
In my app I have a SynchManager that using NSoperations performs synch in background and store new records in the persistent sqlite store only if not alredy stored.
Basically what I do is:
execute a fetch request which retrieves a collections of stored ids (in my case these ids are strings representing urls)
before insert a new object in the store I call a method like "shouldImportObject:", which basically test that the url is not already stored in the database. This is a simplified implementation sample:
for (id objectID in ids) {
if ([objectID isEqual:objectToImport.objectID]) {
return NO;
}
}
return YES;
I need some guidance on adding / updating SQL records using EF. Lets say I am writing an application that stores info about files on a hard disk, into an EF4 database. When you press a button, it will scan all the files in a specified path (maybe the whole drive), and store information in the database like the file size, change date etc. Sometimes the file will already be recorded from a previous run, so its properties should be updated; sometimes a batch of files will be detected for the first time and will need to be added.
I am using EF4, and I am seeking the most efficient way of adding new file information and updating existing records. As I understand it, when I press the search button and files are detected, I will have to check for the presence of a file entity, retrieve its ID field, and use that to add or update related information; but if it does not exist already, I will need to create a tree that represents it and its related objects (eg. its folder path), and add that. I will also have to handle the merging of the folder path object as well.
It occurs to me that if there are many millions of files, as there might be on a server, loading the whole database into the context is not ideal or practical. So for every file, I might conceivably have to make a round trip to the database on disk to detect if the entry exists already, retrieve its ID if it exists, then another trip to update. Is there a more efficient way I can insert/update multiple file object trees in one trip to the DB? If there was an Entity context method like 'Insert If It Doesnt Exist And Update If It Does' for example, then I could wrap up multiple in a transaction?
I imagine this would be a fairly common requirement, how is it best done in EF? Any thoughts would be appreciated.(oh my DB is SQLITE if that makes a difference)
You can check if the record already exists in the DB. If not, create and add the record. You can then set the fields of the record which will be common to insert and update like the sample code below.
var strategy_property_in_db = _dbContext.ParameterValues().Where(r => r.Name == strategy_property.Name).FirstOrDefault();
if (strategy_property_in_db == null)
{
strategy_property_in_db = new ParameterValue() { Name = strategy_property.Name };
_dbContext.AddObject("ParameterValues", strategy_property_in_db);
}
strategy_property_in_db.Value = strategy_property.Value;