Collections
Functionality
SymmetricDiff
Compare two dictionaries in order to be able to merge incoming data easily.
using WallyMathieu.Collections;
...
public async Task<string> Post(IEnumerable<ProductModel> body)
{
var comparison = db.Products.ToDictionary(c => c.Key)
.SymmetricDiff(body.ToDictionary(c => c.Id));
foreach (var valueIntersection in comparison.Intersection)
{
valueIntersection.Left.Description = valueIntersection.Right.Name;
}
foreach (var (key,incoming) in comparison.OnlyInRight)
{
db.Add(new Product
{
Key = incoming.Id,
Description = incoming.Name
});
}
foreach (var (key,outgoing) in comparison.OnlyInLeft)
{
db.Remove(outgoing);
}
await db.SaveChangesAsync();
...Compare two hash sets in order to quickly understand what's incoming and what's outgoing.
using WallyMathieu.Collections;
...
public async Task Post(PublishedProductsModel body)
{
var comparison = db.PublishedProducts.ToHashSet()
.SymmetricDiff(body.ProductIds.ToHashSet());
foreach (var product in db.Products.Where(p=>comparison.OnlyInRight.Contains(p.Key)))
{
await publisher.Publish(product);
}
foreach (var product in db.Products.Where(p=>comparison.OnlyInLeft.Contains(p.Key)))
{
await publisher.UnPublish(product);
}
...BatchesOf
In order to get subsets of a list with a specific number of elements.
using WallyMathieu.Collections;
...
foreach (var batch in hugelist.BatchesOf(2000))
{
await Process(batch);
await db.SaveChangesAsync();
}
...Pairwise
Used to iterate over collection and get the collection elements pairwise. Yields the result of the application of the map function over each pair.
using WallyMathieu.Collections;
...
var pairs = Enumerable.Range(0,4).Pairwise().ToArray();
// will be
Assert.Equal(new[] { (0, 1), (1, 2), (2, 3) },pairs);
