[dynamodb] Add BatchGetItem function (#71)

dynamodb/client_op_batch_get_item.go

@@ -0,0 +1,82 @@
+package dynamodb
+
+import (
+	SDK "github.com/aws/aws-sdk-go/service/dynamodb"
+	"github.com/aws/aws-sdk-go/service/dynamodb/dynamodbattribute"
+)
+
+// BatchGetAll executes batch_get_item operation
+func (svc *DynamoDB) BatchGetAll(in BatchGetAllRequest) (*BatchGetAllResponse, error) {
+	o, err := svc.client.BatchGetItem(in.ToInput())
+	if err != nil {
+		return nil, err
+	}
+	return newBatchGetItemResponse(o), nil
+}
+
+type BatchGetAllRequest struct {
+	RequestItems           map[string]KeysAndAttributes
+	ReturnConsumedCapacity string
+}
+
+func (r *BatchGetAllRequest) ToInput() *SDK.BatchGetItemInput {
+	i := SDK.BatchGetItemInput{}
+	i.RequestItems = make(map[string]*SDK.KeysAndAttributes, len(r.RequestItems))
+	for key, item := range r.RequestItems {
+		i.RequestItems[key] = item.ToSDK()
+	}
+	if r.ReturnConsumedCapacity != "" {
+		i.ReturnConsumedCapacity = &r.ReturnConsumedCapacity
+	}
+	return &i
+}
+
+type BatchGetAllResponse struct {
+	Responses        map[string][]map[string]*SDK.AttributeValue
+	UnprocessedKeys  map[string]KeysAndAttributes
+	ConsumedCapacity []ConsumedCapacity
+}
+
+func newBatchGetItemResponse(output *SDK.BatchGetItemOutput) *BatchGetAllResponse {
+	r := &BatchGetAllResponse{}
+	if output == nil {
+		return r
+	}
+	r.ConsumedCapacity = newConsumedCapacities(output.ConsumedCapacity)
+	r.Responses = output.Responses
+
+	r.UnprocessedKeys = make(map[string]KeysAndAttributes, len(output.UnprocessedKeys))
+	for key, val := range output.UnprocessedKeys {
+		r.UnprocessedKeys[key] = newKeysAndAttributes(val)
+	}
+	return r
+}
+
+// UnmarshalItems unmarshals given slice pointer struct from DynamoDB item result to mapping.
+//     e.g. err = Unmarshal(&[]*yourStruct)
+// The struct tag `dynamodb:""` is used to unmarshal.
+func (r BatchGetAllResponse) Unmarshal(v interface{}) error {
+	return r.UnmarshalWithTagName(v, defaultResultTag)
+}
+
+// UnmarshalWithTagName unmarshals given slice pointer struct and tag name from DynamoDB item result to mapping.
+func (r BatchGetAllResponse) UnmarshalWithTagName(v interface{}, structTag string) error {
+	decoder := dynamodbattribute.NewDecoder()
+	decoder.TagKey = structTag
+
+	itemsMap := make(map[string]*SDK.AttributeValue, len(r.Responses))
+	for tableName, i := range r.Responses {
+		items := make([]*SDK.AttributeValue, len(i))
+		for i, m := range i {
+			items[i] = &SDK.AttributeValue{M: m}
+		}
+		itemsMap[tableName] = &SDK.AttributeValue{
+			L: items,
+		}
+	}
+	val := &SDK.AttributeValue{M: itemsMap}
+	if err := decoder.Decode(val, v); err != nil {
+		return err
+	}
+	return nil
+}

dynamodb/table_op_batch_get_item.go

@@ -0,0 +1,73 @@
+package dynamodb
+
+import (
+	SDK "github.com/aws/aws-sdk-go/service/dynamodb"
+	"github.com/aws/aws-sdk-go/service/dynamodb/dynamodbattribute"
+)
+
+// BatchGet executes batch_get_item operation
+func (t *Table) BatchGet(req BatchGetRequest) (*BatchGetResponse, error) {
+	res, err := t.service.client.BatchGetItem(req.ToInput(t.nameWithPrefix))
+	if err != nil {
+		return nil, err
+	}
+	return newBatchGetResponse(res, t.nameWithPrefix), nil
+}
+
+type BatchGetRequest struct {
+	RequestItems           KeysAndAttributes
+	ReturnConsumedCapacity string
+}
+
+func (r *BatchGetRequest) ToInput(tableName string) *SDK.BatchGetItemInput {
+	i := SDK.BatchGetItemInput{}
+	i.RequestItems = make(map[string]*SDK.KeysAndAttributes)
+	i.RequestItems[tableName] = r.RequestItems.ToSDK()
+	if r.ReturnConsumedCapacity != "" {
+		i.ReturnConsumedCapacity = &r.ReturnConsumedCapacity
+	}
+	return &i
+}
+
+type BatchGetResponse struct {
+	Responses        []map[string]*SDK.AttributeValue
+	UnprocessedKeys  KeysAndAttributes
+	ConsumedCapacity []ConsumedCapacity
+}
+
+func newBatchGetResponse(output *SDK.BatchGetItemOutput, tableName string) *BatchGetResponse {
+	r := &BatchGetResponse{}
+	if output == nil {
+		return r
+	}
+	if res, ok := output.Responses[tableName]; ok {
+		r.Responses = res
+	}
+	if keys, ok := output.UnprocessedKeys[tableName]; ok {
+		r.UnprocessedKeys = newKeysAndAttributes(keys)
+	}
+	r.ConsumedCapacity = newConsumedCapacities(output.ConsumedCapacity)
+	return r
+}
+
+func (r BatchGetResponse) Unmarshal(v interface{}) error {
+	return r.UnmarshalWithTagName(v, defaultResultTag)
+}
+
+// UnmarshalWithTagName unmarshals given slice pointer sturct and tag name from DynamoDB item result to mapping.
+func (r BatchGetResponse) UnmarshalWithTagName(v interface{}, structTag string) error {
+	decoder := dynamodbattribute.NewDecoder()
+	decoder.TagKey = structTag
+
+	items := make([]*SDK.AttributeValue, len(r.Responses))
+	for i, m := range r.Responses {
+		items[i] = &SDK.AttributeValue{M: m}
+	}
+	val := &SDK.AttributeValue{
+		L: items,
+	}
+	if err := decoder.Decode(val, v); err != nil {
+		return err
+	}
+	return nil
+}