evalphobia/aws-sdk-go-v2-wrapper

package dynamodb

import (
    "context"

    SDK "github.com/aws/aws-sdk-go-v2/service/dynamodb"

    "github.com/evalphobia/aws-sdk-go-v2-wrapper/errors"
    "github.com/evalphobia/aws-sdk-go-v2-wrapper/private/pointers"
)

// Scan executes `Scan` operation.
func (svc *DynamoDB) Scan(ctx context.Context, r ScanRequest) (*ScanResult, error) {
    in, err := r.ToInput()
    if err != nil {
        return nil, err
    }

    out, err := svc.RawScan(ctx, in)
    if err == nil {
        return NewScanResult(out), nil
    }

    err = svc.errWrap(errors.ErrorData{
        Err:          err,
        AWSOperation: "Scan",
    })
    svc.Errorf(err.Error())
    return nil, err
}

// ScanRequest has parameters for `Scan` operation.
type ScanRequest struct {
    TableName string

    // optional
    ConsistentRead            bool
    ExclusiveStartKey         map[string]AttributeValue
    ExpressionAttributeNames  map[string]string
    ExpressionAttributeValues map[string]AttributeValue
    FilterExpression          string
    IndexName                 string
    Limit                     int64
    ProjectionExpression      string
    ReturnConsumedCapacity    ReturnConsumedCapacity
    Segment                   int64
    Select                    Select
    TotalSegments             int64

    XConditions XConditions
}

func (r ScanRequest) ToInput() (*SDK.ScanInput, error) {
    in := &SDK.ScanInput{}

    if r.TableName != "" {
        in.TableName = pointers.String(r.TableName)
    }

    if r.ConsistentRead {
        in.ConsistentRead = pointers.Bool(r.ConsistentRead)
    }

    if len(r.ExclusiveStartKey) != 0 {
        m := make(map[string]SDK.AttributeValue, len(r.ExclusiveStartKey))
        for key, val := range r.ExclusiveStartKey {
            m[key] = val.ToSDK()
        }
        in.ExclusiveStartKey = m
    }

    in.ExpressionAttributeNames = r.ExpressionAttributeNames

    if len(r.ExpressionAttributeValues) != 0 {
        m := make(map[string]SDK.AttributeValue, len(r.ExpressionAttributeValues))
        for key, val := range r.ExpressionAttributeValues {
            m[key] = val.ToSDK()
        }
        in.ExpressionAttributeValues = m
    }

    if r.FilterExpression != "" {
        in.FilterExpression = pointers.String(r.FilterExpression)
    }
    if r.IndexName != "" {
        in.IndexName = pointers.String(r.IndexName)
    }

    if r.Limit != 0 {
        in.Limit = pointers.Long64(r.Limit)
    }
    if r.ProjectionExpression != "" {
        in.ProjectionExpression = pointers.String(r.ProjectionExpression)
    }

    in.ReturnConsumedCapacity = SDK.ReturnConsumedCapacity(r.ReturnConsumedCapacity)

    in.Select = SDK.Select(r.Select)

    if r.XConditions.hasValue() {
        expr, err := r.XConditions.Build()
        if err != nil {
            return nil, err
        }
        in.ExpressionAttributeNames = expr.Names()
        in.ExpressionAttributeValues = expr.Values()
        in.FilterExpression = expr.Filter()
        in.ProjectionExpression = expr.Projection()
    }
    return in, nil
}

// ScanResult contains results from `Scan` operation.
type ScanResult struct {
    ConsumedCapacity ConsumedCapacity
    Count            int64
    Items            []map[string]SDK.AttributeValue // keep original type to reduce unmarshal cost
    LastEvaluatedKey map[string]AttributeValue
    ScannedCount     int64
}

func NewScanResult(output *SDK.ScanResponse) *ScanResult {
    r := &ScanResult{}
    if output == nil {
        return r
    }

    if output.ConsumedCapacity != nil {
        r.ConsumedCapacity = newConsumedCapacity(*output.ConsumedCapacity)
    }

    if output.Count != nil {
        r.Count = *output.Count
    }

    r.Items = output.Items
    r.LastEvaluatedKey = newAttributeValueMap(output.LastEvaluatedKey)

    if output.ScannedCount != nil {
        r.ScannedCount = *output.ScannedCount
    }
    return r
}

func (r ScanResult) ToSliceMap() ([]map[string]interface{}, error) {
    return ToSliceMapValues(r.Items), nil
}

func (r ScanResult) Unmarshal(out interface{}) error {
    return RawUnmarshalAttributeValues(r.Items, out)
}