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sql-aggregator.go
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sql-aggregator.go
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package backends
// this file satifies the Aggregator interface for SqlBackend
import (
"database/sql"
"reflect"
"github.com/ghetzel/go-stockutil/typeutil"
"github.com/ghetzel/pivot/v3/dal"
"github.com/ghetzel/pivot/v3/filter"
"github.com/ghetzel/pivot/v3/filter/generators"
)
type sqlAggResultFunc func(*sql.Rows, *generators.Sql, *dal.Collection, *filter.Filter) (interface{}, error)
func (self *SqlBackend) Sum(collection *dal.Collection, field string, f ...*filter.Filter) (float64, error) {
return self.aggregateFloat(collection, filter.Sum, field, f)
}
func (self *SqlBackend) Count(collection *dal.Collection, f ...*filter.Filter) (uint64, error) {
whatToCount := collection.IdentityField
if typeutil.IsZero(whatToCount) {
whatToCount = `1`
}
v, err := self.aggregateFloat(collection, filter.Count, whatToCount, f)
return uint64(v), err
}
func (self *SqlBackend) Minimum(collection *dal.Collection, field string, f ...*filter.Filter) (float64, error) {
return self.aggregateFloat(collection, filter.Minimum, field, f)
}
func (self *SqlBackend) Maximum(collection *dal.Collection, field string, f ...*filter.Filter) (float64, error) {
return self.aggregateFloat(collection, filter.Maximum, field, f)
}
func (self *SqlBackend) Average(collection *dal.Collection, field string, f ...*filter.Filter) (float64, error) {
return self.aggregateFloat(collection, filter.Average, field, f)
}
func (self *SqlBackend) GroupBy(collection *dal.Collection, groupBy []string, aggregates []filter.Aggregate, f ...*filter.Filter) (*dal.RecordSet, error) {
if result, err := self.aggregate(collection, groupBy, aggregates, f, self.extractRecordSet); err == nil {
return result.(*dal.RecordSet), nil
} else {
return nil, err
}
}
func (self *SqlBackend) aggregateFloat(collection *dal.Collection, aggregation filter.Aggregation, field string, f []*filter.Filter) (float64, error) {
if result, err := self.aggregate(collection, nil, []filter.Aggregate{
{
Aggregation: aggregation,
Field: field,
},
}, f, self.extractSingleFloat64); err == nil {
return result.(float64), nil
} else {
return 0, err
}
}
func (self *SqlBackend) aggregate(collection *dal.Collection, groupBy []string, aggregates []filter.Aggregate, f []*filter.Filter, resultFn sqlAggResultFunc) (interface{}, error) {
queryGen := self.makeQueryGen(collection)
var flt *filter.Filter
if len(f) == 0 {
flt = filter.New()
} else {
flt = f[0]
}
for _, g := range groupBy {
queryGen.GroupByField(g)
}
for _, agg := range aggregates {
queryGen.AggregateByField(agg.Aggregation, agg.Field)
}
if err := queryGen.Initialize(collection.Name); err == nil {
if stmt, err := filter.Render(queryGen, collection.Name, flt); err == nil {
querylog.Debugf("[%T] %s %v", self, string(stmt[:]), queryGen.GetValues())
// perform query
if rows, err := self.db.Query(string(stmt[:]), queryGen.GetValues()...); err == nil {
defer rows.Close()
return resultFn(rows, queryGen, collection, flt)
} else {
return nil, err
}
} else {
return nil, err
}
} else {
return nil, err
}
}
func (self *SqlBackend) AggregatorConnectionString() *dal.ConnectionString {
return self.GetConnectionString()
}
func (self *SqlBackend) AggregatorInitialize(parent Backend) error {
return nil
}
func (self *SqlBackend) extractSingleFloat64(rows *sql.Rows, _ *generators.Sql, _ *dal.Collection, _ *filter.Filter) (interface{}, error) {
if rows.Next() {
var rv sql.NullFloat64
if err := rows.Scan(&rv); err == nil {
return rv.Float64, nil
} else {
return float64(0), err
}
} else {
return float64(0), nil
}
}
func (self *SqlBackend) extractRecordSet(rows *sql.Rows, queryGen *generators.Sql, collection *dal.Collection, flt *filter.Filter) (interface{}, error) {
recordset := dal.NewRecordSet()
if columns, err := rows.Columns(); err == nil {
for rows.Next() {
if record, err := self.scanFnValueToRecord(queryGen, collection, columns, reflect.ValueOf(rows.Scan), flt.Fields); err == nil {
recordset.Push(record)
} else {
return nil, err
}
}
} else {
return nil, err
}
return recordset, nil
}