Scan
When scanning for rows, you can use filters the same as you would any query. For more information on filters, see the Filters section.
The scan method will be scoped to your Entity. This means your results will only include records that match the Entity defined in the model.
Fun Fact! Scanning DynamoDB is one of the least effective mechanisms for retrieving items from DynamoDB.
Example Setup
Table Definition
{ "TableName": "electro", "KeySchema": [ { "AttributeName": "pk", "KeyType": "HASH" }, { "AttributeName": "sk", "KeyType": "RANGE" } ], "AttributeDefinitions": [ { "AttributeName": "pk", "AttributeType": "S" }, { "AttributeName": "sk", "AttributeType": "S" }, { "AttributeName": "gsi1pk", "AttributeType": "S" }, { "AttributeName": "gsi1sk", "AttributeType": "S" } ], "GlobalSecondaryIndexes": [ { "IndexName": "gsi1pk-gsi1sk-index", "KeySchema": [ { "AttributeName": "gsi1pk", "KeyType": "HASH" }, { "AttributeName": "gsi1sk", "KeyType": "RANGE" } ], "Projection": { "ProjectionType": "ALL" } }, { "IndexName": "gsi2pk-gsi2sk-index", "KeySchema": [ { "AttributeName": "gsi2pk", "KeyType": "HASH" }, { "AttributeName": "gsi2sk", "KeyType": "RANGE" } ], "Projection": { "ProjectionType": "ALL" } } ], "BillingMode": "PAY_PER_REQUEST" }(Example code on this page that references the entityExample Entity
import DynamoDB from "aws-sdk/clients/dynamodb"; import { Entity } from "electrodb"; const client = new DynamoDB.DocumentClient(); const table = "electro"; const StoreLocations = new Entity( { model: { service: "MallStoreDirectory", entity: "MallStore", version: "1", }, attributes: { cityId: { type: "string", required: true, }, mallId: { type: "string", required: true, }, storeId: { type: "string", required: true, }, buildingId: { type: "string", required: true, }, unitId: { type: "string", required: true, }, category: { type: [ "spite store", "food/coffee", "food/meal", "clothing", "electronics", "department", "misc", ], required: true, }, leaseEndDate: { type: "string", required: true, }, rent: { type: "string", required: true, validate: /^(\d+\.\d{2})$/, }, discount: { type: "string", required: false, default: "0.00", validate: /^(\d+\.\d{2})$/, }, tenants: { type: "set", items: "string", }, warnings: { type: "number", default: 0, }, deposit: { type: "number", }, contact: { type: "set", items: "string", }, rentalAgreement: { type: "list", items: { type: "map", properties: { type: { type: "string", }, detail: { type: "string", }, }, }, }, petFee: { type: "number", }, fees: { type: "number", }, tags: { type: "set", items: "string", }, }, indexes: { stores: { pk: { field: "pk", composite: ["cityId", "mallId"], }, sk: { field: "sk", composite: ["buildingId", "storeId"], }, }, units: { index: "gsi1pk-gsi1sk-index", pk: { field: "gsi1pk", composite: ["mallId"], }, sk: { field: "gsi1sk", composite: ["buildingId", "unitId"], }, }, leases: { index: "gsi2pk-gsi2sk-index", pk: { field: "gsi2pk", composite: ["storeId"], }, sk: { field: "gsi2sk", composite: ["leaseEndDate"], }, }, }, }, { table, client }, );StoreLocationsuses the following Entity and Table Definition found below)
await StoreLocations.scan
.where(
({ category }, { eq }) => `
${eq(category, "food/coffee")} OR ${eq(category, "spite store")}
`,
)
.where(
({ leaseEndDate }, { between }) => `
${between(leaseEndDate, "2020-03", "2020-04")}
`,
)
.go();Response Format
{
data: Array<YOUR_SCHEMA>,
cursor: string | undefined
}Equivalent Parameters
{
"TableName": "StoreDirectory",
"ExpressionAttributeNames": {
"#category": "category",
"#leaseEndDate": "leaseEndDate",
"#pk": "pk",
"#sk": "sk",
"#__edb_e__": "__edb_e__",
"#__edb_v__": "__edb_v__"
},
"ExpressionAttributeValues": {
":category_w1": "food/coffee",
":category_w2": "spite store",
":leaseEndDate_w1": "2020-03",
":leaseEndDate_w2": "2020-04",
":pk": "$mallstoredirectory#cityid_",
":sk": "$mallstore_1#buildingid_",
":__edb_e__": "MallStore",
":__edb_v__": "1"
},
"FilterExpression": "begins_with(#pk, :pk) AND #__edb_e__ = :__edb_e__ AND #__edb_v__ = :__edb_v__ AND begins_with(#sk, :sk) AND (#category = :category_w1 OR #category = :category_w2) AND (#leaseEndDate between :leaseEndDate_w1 and :leaseEndDate_w2)"
}Execution Options
Query options can be added the .params() and .go() to change query behavior or add customer parameters to a query.
By default, ElectroDB enables you to work with records as the names and properties defined in the model. Additionally, it removes the need to deal directly with the docClient parameters which can be complex for a team without as much experience with DynamoDB. The Query Options object can be passed to both the .params() and .go() methods when building you query. Below are the options available:
{
params?: object;
table?: string;
data?: 'raw' | 'includeKeys' | 'attributes';
pager?: 'raw' | 'cursor';
originalErr?: boolean;
response?: "default" | "none" | "all_old" | "updated_old" | "all_new" | "updated_new";
ignoreOwnership?: boolean;
limit?: number;
count?: number;
pages?: number | 'all';
logger?: (event) => void;
listeners Array<(event) => void>;
attributes?: string[];
order?: 'asc' | 'desc';
};Query Execution Options
params
Default Value: {}
Properties added to this object will be merged onto the params sent to the document client. Any conflicts with ElectroDB will favor the params specified here. Consider this an escape hatch for options not yet supported by ElectroDB.
table
Default Value: (from constructor) Use a different table than the one defined in Service Options and/or Entity Options.
attributes
Default Value: (all attributes)
The attributes query option allows you to specify ProjectionExpression Attributes for your get or query operation.
data
Default Value: "attributes"
Accepts the values 'raw', 'includeKeys', 'attributes' or undefined. Use 'raw' to return query results as they were returned by the docClient. Use 'includeKeys' to include item partition and sort key values in your return object. By default, ElectroDB does not return partition, sort, or global keys in its response.
originalErr
Default Value: false
By default, ElectroDB alters the stacktrace of any exceptions thrown by the DynamoDB client to give better visibility to the developer. Set this value equal to true to turn off this functionality and return the error unchanged.
response
Default Value: "default"
Used as a convenience for applying the DynamoDB parameter ReturnValues. The options here are the same as the parameter values for the DocumentClient except lowercase. The "none" option will cause the method to return null and will bypass ElectroDB’s response formatting — useful if formatting performance is a concern.
ignoreOwnership
Default Value: false
By default, ElectroDB interrogates items returned from a query for the presence of matching entity “identifiers”. This helps to ensure other entities, or other versions of an entity, are filtered from your results. If you are using ElectroDB with an existing table/dataset you can turn off this feature by setting this property to true.
limit
Default Value: none
Used a convenience wrapper for the DynamoDB parameter Limit [read more]. When limit is paired option pages:"all", ElectroDB will paginate DynamoDB until the limit is at least reached or all items for that query have been returned; this means you may receive more items than your specified limit but never less.
Note: If your use case requires returning a specific number of items at a time, the
countoption is the better option.
count
Default Value: none
A target for the number of items to return from DynamoDB. If this option is passed, Queries on entities will paginate DynamoDB until the items found match the count is reached or all items for that query have been returned. It is important to understand that this option may result in ElectroDB making multiple calls to DynamoDB to satisfy the count. For this reason, you should also consider using the pages option to limit the number of requests (or “pages”) made to DynamoDB.
pages
Default Value: 1
How many DynamoDB pages should a query iterate through before stopping. To have ElectroDB automatically paginate through all results, pass the string value 'all'.
order
Default Value: ‘asc’
Convenience option for ScanIndexForward, to the change the order of queries based on your index’s Sort Key — valid options include ‘asc’ and ‘desc’. [read more]
listeners
Default Value: []
An array of callbacks that are invoked when internal ElectroDB events occur.
logger
Default Value: none A convenience option for a single event listener that semantically can be used for logging.