Session: Querying: How to perform dynamic aggregation?

Dynamic aggregation can be performed using AggregateBy method. Internally such aggregation is an extended faceted search.

Syntax

DynamicAggregationQuery<TResult> AggregateBy<TResult>(
	this IQueryable<TResult> queryable,
	string path,
	string displayName = null) { ... }

DynamicAggregationQuery<TResult> AggregateBy<TResult>(
	this IQueryable<TResult> queryable,
	Expression<Func<TResult, object>> path) { ... }

DynamicAggregationQuery<TResult> AggregateBy<TResult>(
	this IQueryable<TResult> queryable,
	Expression<Func<TResult, object>> path,
	string displayName) { ... }

Example I - summing

// sum up all order prices
// for each customer
// where price is higher than 500
FacetResults aggregationResults = session.Query<Order>("Orders/All")
	.Where(x => x.TotalPrice > 500)
	.AggregateBy(x => x.CustomerId)
		.SumOn(x => x.TotalPrice)
	.ToList();

FacetResult customerAggregation = aggregationResults.Results["CustomerId"];
double? sum = customerAggregation.Values[0].Sum;

Example II - counting

// count all orders
// for each customer
// where price is higher than 500
FacetResults aggregationResults = session.Query<Order>("Orders/All")
	.Where(x => x.TotalPrice > 500)
	.AggregateBy(x => x.CustomerId)
		.CountOn(x => x.TotalPrice)
	.ToList();

FacetResult customerAggregation = aggregationResults.Results["CustomerId"];
int? count = customerAggregation.Values[0].Count;

Example III - average

// count price average for orders
// for each customer
// where price is higher than 500
FacetResults aggregationResults = session.Query<Order>("Orders/All")
	.Where(x => x.TotalPrice > 500)
	.AggregateBy(x => x.CustomerId)
		.AverageOn(x => x.TotalPrice)
	.ToList();

FacetResult customerAggregation = aggregationResults.Results["CustomerId"];
double? average = customerAggregation.Values[0].Average;

Example IV - maximum and minimum

// count max and min price for orders
// for each customer
// where price is higher than 500
FacetResults aggregationResults = session.Query<Order>("Orders/All")
	.Where(x => x.TotalPrice > 500)
	.AggregateBy(x => x.CustomerId)
		.MinOn(x => x.TotalPrice)
		.MaxOn(x => x.TotalPrice)
	.ToList();

FacetResult customerAggregation = aggregationResults.Results["CustomerId"];
double? min = customerAggregation.Values[0].Min;
double? max = customerAggregation.Values[0].Max;

Example V - adding ranges

FacetResults aggregationResults = session.Query<Order>("Orders/All")
	.AggregateBy(x => x.CustomerId)
		.AddRanges(x => x.TotalPrice < 100)
		.AddRanges(x => x.TotalPrice >= 100 && x.TotalPrice < 500)
		.AddRanges(x => x.TotalPrice >= 500 && x.TotalPrice < 1000)
		.AddRanges(x => x.TotalPrice >= 1000)
	.ToList();

FacetResult customerAggregation = aggregationResults.Results["CustomerId"];
FacetValue range1 = customerAggregation.Values.First(x => x.Range == "[NULL to Dx100]");
FacetValue range2 = customerAggregation.Values.First(x => x.Range == "{Dx100 to Dx500]");
FacetValue range3 = customerAggregation.Values.First(x => x.Range == "{Dx500 to Dx1000]");
FacetValue range4 = customerAggregation.Values.First(x => x.Range == "{Dx1000 to NULL]");

Example VI - multiple aggregations

// sum up all order prices
// for each customer
// count price average for all orders
// for each company
FacetResults aggregationResults = session.Query<Order>("Orders/All")
	.AggregateBy(x => x.CustomerId)
		.SumOn(x => x.TotalPrice)
	.AndAggregateOn(x => x.CompanyId)
		.AverageOn(x => x.TotalPrice)
	.ToList();

FacetResult customerAggregation = aggregationResults.Results["CustomerId"];
FacetResult companyAggregation = aggregationResults.Results["CompanyId"];

double? sum = customerAggregation.Values[0].Sum;
double? average = companyAggregation.Values[0].Average;