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dynamo-indexer.go
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dynamo-indexer.go
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package backends
import (
"fmt"
"math"
"strings"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/service/dynamodb"
"github.com/PerformLine/pivot/v3/dal"
"github.com/PerformLine/pivot/v3/filter"
)
func (self *DynamoBackend) IndexConnectionString() *dal.ConnectionString {
return &self.cs
}
func (self *DynamoBackend) IndexInitialize(Backend) error {
return nil
}
func (self *DynamoBackend) GetBackend() Backend {
return self
}
func (self *DynamoBackend) IndexExists(collection *dal.Collection, id interface{}) bool {
return self.Exists(collection.Name, id)
}
func (self *DynamoBackend) IndexRetrieve(collection *dal.Collection, id interface{}) (*dal.Record, error) {
return self.Retrieve(collection.Name, id)
}
func (self *DynamoBackend) IndexRemove(collection *dal.Collection, ids []interface{}) error {
return nil
}
func (self *DynamoBackend) Index(collection *dal.Collection, records *dal.RecordSet) error {
return nil
}
func (self *DynamoBackend) QueryFunc(collection *dal.Collection, flt *filter.Filter, resultFn IndexResultFunc) error {
if err := self.validateFilter(collection, flt); err != nil {
return fmt.Errorf("Cannot validate filter: %v", err)
}
ctx := aws.BackgroundContext()
pageNumber := 0
var processed int
// NOTE: we use the DynamoDB table name instead of .GetIndexName() because we only partially
// support querying (range scans only), so we're regularly going to be dealing with
// external indices with potentially-different names. If this function is being called, that means
// we're using DynamoDB as an indexer and we want the underlying name intact.
if flt == nil || flt.IsMatchAll() {
scan := &dynamodb.ScanInput{
TableName: aws.String(collection.Name),
Select: aws.String(`ALL_ATTRIBUTES`),
}
if flt.Limit > 0 {
scan.SetLimit(int64(flt.Limit))
}
return self.db.ScanPagesWithContext(ctx, scan, func(page *dynamodb.ScanOutput, lastPage bool) bool {
pageNumber += 1
return self.iterResult(
collection,
flt,
page.Items,
processed,
*page.Count,
pageNumber,
lastPage,
resultFn,
)
})
} else {
query := &dynamodb.QueryInput{
TableName: aws.String(collection.Name),
Select: aws.String(`ALL_ATTRIBUTES`),
}
if kcond, _, attrNames, attrValues, attrFieldMap, err := dynamoExprFromFilter(collection, flt); err == nil {
query = query.SetKeyConditionExpression(strings.Join(kcond, ` AND `))
query = query.SetExpressionAttributeNames(attrNames)
query = query.SetExpressionAttributeValues(
dynamoToDynamoAttributes(collection, attrValues, attrFieldMap),
)
return self.db.QueryPagesWithContext(ctx, query, func(page *dynamodb.QueryOutput, lastPage bool) bool {
pageNumber += 1
return self.iterResult(
collection,
flt,
page.Items,
processed,
*page.Count,
pageNumber,
lastPage,
resultFn,
)
})
} else {
return fmt.Errorf("Cannot get DynamoDB expression from filter: %v", err)
}
}
}
func dynamoExprFromFilter(collection *dal.Collection, flt *filter.Filter) ([]string, []string, map[string]*string, map[string]interface{}, map[string]string, error) {
fieldId := 0
valId := 0
keyCondExpr := []string{}
condExpr := []string{}
attrNames := map[string]*string{}
attrValues := map[string]interface{}{}
attrFieldMap := map[string]string{}
if flt != nil {
for _, criterion := range flt.Criteria {
if op := dynamoToNativeOp(&criterion); op != `` {
ors := make([]string, 0)
for _, value := range criterion.Values {
ors = append(ors, fmt.Sprintf("#F%d %v :v%d", fieldId, op, valId))
attrValues[fmt.Sprintf(":v%d", valId)] = value
attrFieldMap[fmt.Sprintf(":v%d", valId)] = criterion.Field
valId += 1
}
attrNames[fmt.Sprintf("#F%d", fieldId)] = aws.String(criterion.Field)
// key conditions
if collection.IsIdentityField(criterion.Field) || collection.IsKeyField(criterion.Field) {
keyCondExpr = append(keyCondExpr, `(`+strings.Join(ors, ` OR `)+`)`)
} else {
condExpr = append(condExpr, `(`+strings.Join(ors, ` OR `)+`)`)
}
fieldId += 1
} else {
return nil, nil, nil, nil, nil, fmt.Errorf("Unsupported operator '%v'", criterion.Operator)
}
}
}
return keyCondExpr, condExpr, attrNames, attrValues, attrFieldMap, nil
}
func (self *DynamoBackend) Query(collection *dal.Collection, f *filter.Filter, resultFns ...IndexResultFunc) (*dal.RecordSet, error) {
if f != nil {
f.Options[`ForceIndexRecord`] = true
}
return DefaultQueryImplementation(self, collection, f, resultFns...)
}
func (self *DynamoBackend) ListValues(collection *dal.Collection, fields []string, flt *filter.Filter) (map[string][]interface{}, error) {
return nil, fmt.Errorf("%T.ListValues: Not Implemented", self)
}
func (self *DynamoBackend) DeleteQuery(collection *dal.Collection, flt *filter.Filter) error {
return fmt.Errorf("%T.DeleteQuery: Not Implemented", self)
}
func (self *DynamoBackend) FlushIndex() error {
return nil
}
func (self *DynamoBackend) validateFilter(collection *dal.Collection, flt *filter.Filter) error {
if flt != nil {
for _, field := range flt.CriteriaFields() {
if collection.IsIdentityField(field) {
continue
}
if collection.IsKeyField(field) {
continue
}
return fmt.Errorf("Filter field '%v' cannot be used: not a key field", field)
}
}
return nil
}
func dynamoToNativeOp(criterion *filter.Criterion) string {
switch criterion.Operator {
case `not`:
return `<>`
case `lt`:
return `<`
case `lte`:
return `<=`
case `gt`:
return `>`
case `gte`:
return `>=`
case `is`, ``:
return `=`
default:
return ``
}
}
func (self *DynamoBackend) iterResult(collection *dal.Collection, flt *filter.Filter, items []map[string]*dynamodb.AttributeValue, processed int, totalResults int64, pageNumber int, lastPage bool, resultFn IndexResultFunc) bool {
if len(items) > 0 {
for _, item := range items {
record, err := dynamoRecordFromItem(collection, nil, item)
// fire off the result handler
if err := resultFn(record, err, IndexPage{
Page: pageNumber,
TotalPages: int(math.Ceil(float64(totalResults) / float64(25))),
Limit: flt.Limit,
Offset: (pageNumber - 1) * 25,
TotalResults: totalResults,
}); err != nil {
return false
}
// perform bounds checking
if processed += 1; flt.Limit > 0 && processed >= flt.Limit {
return false
}
}
return !lastPage
} else {
return false
}
}