Question
I have created a method that filters my dataset. I also created another method that counts the amount of items there are with the filters applied. This method looks like this:
return new Count
{
Address = this.Filter(/* paramters to filter */)
.GroupBy(person => person.Address.City)
.Select(group => new Amount<string>
{
Type = group.Key /* so the city */,
Count = group.Count()
}),
};
Count has a couple of lists of amount objects. The amount objects holds the name of what it will filter on and a count of how many the filter contains.
this.Filter()
Is a private method that will return an IQueryable from the DbContext.
Everything works, however, it is very slow with a large amount of data. The reason for this is that the GroupBy() and the Count() could not be translated and will be evaluated locally. It gives the following warnings:
warn: Microsoft.EntityFrameworkCore.Query[20500]
The LINQ expression 'GroupBy([entity.RequestRating], [entity])' could not be translated and will be evaluated locally.
warn: Microsoft.EntityFrameworkCore.Query[20500]
The LINQ expression 'Count()' could not be translated and will be evaluated locally.
warn: Microsoft.EntityFrameworkCore.Query[20500]
The LINQ expression 'Count()' could not be translated and will be evaluated locally.
What would be a better approach to this? This is a ASP.NET CORE project
Accepted Answer
Try this:
var amountList = Persons.Where(paramters to filter)
.GroupBy(person => person.Address.City)
.Select(group => new Amount()
{
City = group.Key,
CityCount = group.Count()
}).Tolist();
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