How to update/remove certain items in a cache object using IMemoryCache?
When getting cache object, I do below...
[HttpGet]
public IEnumerable<string> Get()
{
string key = "ALLCar-Key";
IList<CarModel> carModelCached = _cache.GetOrCreate(key, entry =>
{
var sampleRecordFromDB = new List<CarModel>
{
new CarModel() { Id = 10, Name = "Hyundai", Year = 1998 },
new CarModel() { Id = 20, Name = "GMC", Year = 2013 },
new CarModel() { Id = 30, Name = "Subaru", Year = 2019 },
};
return sampleRecordFromDB.ToList();
});
return carModelCached;
}
but, if after I do an update/insert, I have to refetch from DB and insert back the updated data to cache.
[HttpPost]
public void Post(List<CarModel> car)
{
string key = "ALLCar-Key";
//fetch from db (removed for brevity...)
var sampleRecordFromDB = new List<CarModel>
{
new CarModel() { Id = 10, Name = "Hyundai", Year = 1998 },
new CarModel() { Id = 20, Name = "GMC", Year = 2020 }, //<<<<------UPDATED VALUE HERE
new CarModel() { Id = 30, Name = "Subaru", Year = 2019 },
};
MemoryCacheEntryOptions options = new MemoryCacheEntryOptions
{
AbsoluteExpiration = DateTime.Now.AddDays(1)
};
_cache.Set(key, sampleRecordFromDB.ToList(), options);
}
My data runs around 150K item, and doing just a simple update to one item then do the cache update is too expensive (performance wise - slow).
Is there a way that I could read from cache and do a single item update/insert from within the cache object?
How to update/remove certain items in a cache object using IMemoryCache?
Pretty simple. The tricky part with your design is the cached item is a collection. Get the collection by key. Update/Remove the collection item using standard LINQ syntax.
static void Main(string[] args)
{
var sampleRecordFromDB = new List<CarModel>
{
new CarModel() { Id = 10, Name = "Hyundai", Year = 1998 },
new CarModel() { Id = 20, Name = "GMC", Year = 2019 },
new CarModel() { Id = 30, Name = "Subaru", Year = 2019 }
};
sampleRecordFromDB.FirstOrDefault(m => m.Id == 20).Year = 2020;
foreach(var item in sampleRecordFromDB)
{
Console.WriteLine($"{item.Id}\t{item.Name}\t{item.Year}");
}
}
Update/Remove the collection item using standard LINQ syntax.
Hi mgebhard,
What I meant was to update/remove the items inside the cache object collection by not filtering the db. Is that even possible, like read the cache object then insert items within that cache object?
What I meant was to update/remove the items inside the cache object collection by not filtering the db. Is that even possible, like read the cache object then insert items within that cache object?
And that's exactly what the code does. It's unclear why you think there is database access in the sample code. Clearly, the collection is cached. The collection might have originated from a DB but that does not matter.
Is there an expression or equivalent query to do the CRUD within a cache collection like below?
var updatedCache = _cache.Get(key).Where(s => s.Id == 20).Year = 2020;
I've already explained what to do. For the second time.... you cached a collection. First you need to get the collection from the cache. Then you can update the collection using LINQ.
I've already explained what to do. For the second time.... you cached a collection. First you need to get the collection from the cache. Then you can update the collection using LINQ.
Thank You a million! and sorry for the confusion. Your solution works!
Member
323 Points
1308 Posts
How to update/remove certain items in a cache object?
Apr 11, 2020 12:47 PM|imperialx|LINK
Hello,
How to update/remove certain items in a cache object using IMemoryCache?
When getting cache object, I do below...
[HttpGet] public IEnumerable<string> Get() { string key = "ALLCar-Key"; IList<CarModel> carModelCached = _cache.GetOrCreate(key, entry => { var sampleRecordFromDB = new List<CarModel> { new CarModel() { Id = 10, Name = "Hyundai", Year = 1998 }, new CarModel() { Id = 20, Name = "GMC", Year = 2013 }, new CarModel() { Id = 30, Name = "Subaru", Year = 2019 }, }; return sampleRecordFromDB.ToList(); }); return carModelCached; }but, if after I do an update/insert, I have to refetch from DB and insert back the updated data to cache.
[HttpPost] public void Post(List<CarModel> car) { string key = "ALLCar-Key"; //fetch from db (removed for brevity...) var sampleRecordFromDB = new List<CarModel> { new CarModel() { Id = 10, Name = "Hyundai", Year = 1998 }, new CarModel() { Id = 20, Name = "GMC", Year = 2020 }, //<<<<------UPDATED VALUE HERE new CarModel() { Id = 30, Name = "Subaru", Year = 2019 }, }; MemoryCacheEntryOptions options = new MemoryCacheEntryOptions { AbsoluteExpiration = DateTime.Now.AddDays(1) }; _cache.Set(key, sampleRecordFromDB.ToList(), options); }My data runs around 150K item, and doing just a simple update to one item then do the cache update is too expensive (performance wise - slow).
Is there a way that I could read from cache and do a single item update/insert from within the cache object?
Thanks,
All-Star
53661 Points
24020 Posts
Re: How to update/remove certain items in a cache object?
Apr 11, 2020 07:05 PM|mgebhard|LINK
Pretty simple. The tricky part with your design is the cached item is a collection. Get the collection by key. Update/Remove the collection item using standard LINQ syntax.
static void Main(string[] args) { var sampleRecordFromDB = new List<CarModel> { new CarModel() { Id = 10, Name = "Hyundai", Year = 1998 }, new CarModel() { Id = 20, Name = "GMC", Year = 2019 }, new CarModel() { Id = 30, Name = "Subaru", Year = 2019 } }; sampleRecordFromDB.FirstOrDefault(m => m.Id == 20).Year = 2020; foreach(var item in sampleRecordFromDB) { Console.WriteLine($"{item.Id}\t{item.Name}\t{item.Year}"); } }Results
10 Hyundai 1998 20 GMC 2020 30 Subaru 2019Member
323 Points
1308 Posts
Re: How to update/remove certain items in a cache object?
Apr 12, 2020 02:54 PM|imperialx|LINK
Hi mgebhard,
What I meant was to update/remove the items inside the cache object collection by not filtering the db. Is that even possible, like read the cache object then insert items within that cache object?
Thanks,
All-Star
53661 Points
24020 Posts
Re: How to update/remove certain items in a cache object?
Apr 12, 2020 03:03 PM|mgebhard|LINK
And that's exactly what the code does. It's unclear why you think there is database access in the sample code. Clearly, the collection is cached. The collection might have originated from a DB but that does not matter.
Member
323 Points
1308 Posts
Re: How to update/remove certain items in a cache object?
Apr 12, 2020 03:10 PM|imperialx|LINK
Hi mgebhard,
In your code below, if i'm not mistaken it's hitting the db which uses LINQ?
Member
323 Points
1308 Posts
Re: How to update/remove certain items in a cache object?
Apr 12, 2020 03:16 PM|imperialx|LINK
Is there an expression or equivalent query to do the CRUD within a cache collection like below?
All-Star
53661 Points
24020 Posts
Re: How to update/remove certain items in a cache object?
Apr 12, 2020 04:14 PM|mgebhard|LINK
No. LINQ also works with collections.
I've already explained what to do. For the second time.... you cached a collection. First you need to get the collection from the cache. Then you can update the collection using LINQ.
Member
323 Points
1308 Posts
Re: How to update/remove certain items in a cache object?
Apr 13, 2020 01:52 AM|imperialx|LINK
Thank You a million! and sorry for the confusion. Your solution works!
Cheers!