Dynamo Request Builder

An intuitive DynamoDB request building API for JavaScript.

Contents

• Installation
• Creating Requests
• Attributes
• Logical Operators
• Executing Requests

Installation

npm install dynamo-request-builder

Creating Requests

Use the DynamoRequestBuilderCreator with a DynamoDB DocumentClient to create a DynamoRequestBuilder.

import DynamoRequestBuilderCreator from "dynamo-request-builder";

const requestBuilder = new DynamoRequestBuilderCreator(dynamoDocClient).create("table_name");

Delete

import { attribute, sizeOf } from "dynamo-request-builder/attributes";
import { or } from "dynamo-request-builder/operators";
import { ReturnValues } from "dynamo-request-builder/return-values";

const request = requestBuilder.delete("partitionKeyName", "partitionKeyValue")
  .withSortKey("sortKeyName", "sortKeyValue") // Sort key condition
  .onlyIfAttribute("attribute").eq("value") // Add an attribute condition
  .onlyIfSizeOfAttribute("attribute").lte(1) // Add a size of attribute condition
  .onlyIf(
    or(attribute("attribute1").gte(1), attribute("attribute2").contains("value")),
    sizeOf("attribute3").eq(2)
  ) // Add multiple attribute conditions
  .returnValues(ReturnValues.AllOld); // Specify values to return

Get

const request = requestBuilder.get("partitionKeyName", "partitionKeyValue")
  .withSortKey("sortKeyName", "sortKeyValue") // Sort key condition
  .getAttributes("attribute", "attribute[0]", "attribute[0].subAttribute") // Specify attributes to retrieve
  .consistentRead(); // Use consistent read

Put

import { attribute, sizeOf } from "dynamo-request-builder/attributes";
import { not } from "dynamo-request-builder/operators";
import { ReturnValues } from "dynamo-request-builder/return-values";

const item = {
  ...
};

const request = requestBuilder.put(item)
  .ifItemNotExists("partitionKeyName", "sortKeyName") // Only put the item if it doesn't already exist
  .onlyIfAttribute("attribute").eq("value") // Add an attribute condition
  .onlyIfSizeOfAttribute("attribute").lte(1) // Add a size of attribute condition
  .onlyIf(
	  not(attribute("attribute1").gte(1)),
	  sizeOf("attribute3").eq(2)
  ) // Add multiple attribute conditions
  .returnValues(ReturnValues.AllOld); // Specify values to return

Query

import { attribute, sizeOf } from "dynamo-request-builder/attributes";
import { or } from "dynamo-request-builder/operators";

const request = requestBuilder.query("partitionKeyName", "partitionKeyValue")
  .whereSortKey("sortKeyName").beginsWith("value") // Add a sort key condition
  .whereAttribute("attribute").eq("value") // Add an attribute condition
  .whereSizeOfAttribute("attribute").lt(1) // Add a size of attribute condition
  .where(
    or(attribute("attribute1").gte(1), attribute("attribute2").contains("value")),
    sizeOf("attribute3").eq(2)
  ) // Add multiple attribute conditions
  .getAttributes("attribute", "attribute[0]", "attribute[0].subAttribute") // Specify attributes to retrieve
  .limit(5) // Specify a limit on the number of items to return
  .useIndex("indexName") // Specify an index to use
  .scanIndexDescending(); // Scan the index in descending order

Scan

import { attribute, sizeOf } from "dynamo-request-builder/attributes";
import { or } from "dynamo-request-builder/operators";

const request = requestBuilder.scan()
  .whereAttribute("attribute").eq("value") // Add an attribute condition
  .whereSizeOfAttribute("attribute").lt(1) // Add a size of attribute condition
  .where(
    or(attribute("attribute1").gte(1), attribute("attribute2").contains("value")),
    sizeOf("attribute3").eq(2)
  ) // Add multiple attribute conditions
  .getAttributes("attribute", "attribute[0]", "attribute[0].subAttribute") // Specify attributes to retrieve
  .limit(5) // Specify a limit on the number of items to return
  .useIndex("indexName") // Specify an index to use

Update

import { attribute, sizeOf, update } from "dynamo-request-builder/attributes";
import { or } from "dynamo-request-builder/operators";

const request = requestBuilder.update("partitionKeyName", "partitionKeyValue")
  .withSortKey("sortKeyName", "sortKeyValue") // Sort key condition
  .updateAttribute("attribute").incrementBy(5) // Add an update operation
  .operations(update("attribute1").add(1, 2, 3), update("attribute2").remove()) // Add multiple update operations
  .onlyIfAttribute("attribute").eq("value") // Add an attribute condition
  .onlyIfSizeOfAttribute("attribute").lte(1) // Add a size of attribute condition
  .onlyIf(
    or(attribute("attribute1").gte(1), attribute("attribute2").contains("value")),
    sizeOf("attribute3").eq(2)
  ) // Add multiple attribute conditions
  .returnValues(UpdateReturnValues.UpdatedNew); // Specify values to return

You can check the generated request parameters for yourself by accessing request.params.

Attributes

The ability to select specific attributes and apply constraint conditions and update operations to them are needed for certain expressions.

Attribute Type	Attribute Selectors	Use Cases	Methods
Condition Attribute	attribute(attributePath), sizeOf(attributePath)	Condition Expressions onlyIfAttribute(attributePath) onlyIfSizeOfAttribute(attributePath) onlyIf(...conditionExpressions) Filter Expressions whereAttribute(attributePath) whereSizeOfAttribute(attributePath) where(...filterExpressions) Key Condition Expressions whereSortKey(sortKeyName)	beginsWith(subString) - Check if the string attribute begins with a substring between(value1, value2) - Check if the numerical attribute is between two values eq(value) - Check if the attribute is equal to a value ne(value) - Check if the attribute is not equal to a value lt(value) - Check if the numerical attribute is less than a value gt(value) - Check if the numerical attribute is greater than a value lte(value) - Check if the numerical attribute is less than or equal to a value gte(value) - Check if the numerical attribute is greater than or equal to a value exists() - Check if the attribute exists notExists() - Check if the attribute doesn't exist contains(value) - Check if a string contains a substring or a set or list contains an element notContains(value) - Check if a string doesn't contain a substring or a set or list doesn't contain an element ofType(type) - Check if an attribute is of a type in(...values) - Check if an attribute is in a list of values
Update Operation Attribute	update(attributePath)	Update Expressions updateAttribute(attributePath) operations(...updateExpressions)	add(...values) - Add a numerical value to the numerical attribute or values to the set attribute increment() - Increment the numerical attribute by 1 incrementBy(value) - Increment the numerical attribute by a value decrement() - Decrement the numerical attribute by 1 decrementBy(value) - Decrement the numerical attribute by a value appendToStartOfList(...values) - Append values to the start of the list attribute appendToEndOfList(...values) - Append values to the end of the list attribute set(value, ifNotExists = false) - Set the value of the attribute (optional only set the value if the attribute doesn't exist) remove() - Remove the attribute removeFromListAt(...indices) - Remove elements from the list attribute at the specific indices removeFromSet(...values) - Remove values from the set attribute

Logical Operators

Logical operators are used to extend the logic of condition expressions, filter expressions and key condition expressions.

Operator	Description
not(conditionExpression)	The condition expression must evaluate to false for the result to be true
and(...conditionExpressions)	All condition expressions must evaluate to true for the result to be true
or(...conditionExpressions)	Only one condition expression must evaluate to true for the result to be true

Executing Requests

Once a request has been created, it can be executed and the return values can be used.

Request Type	Inheriting Types	Methods
BaseRequest	All	execFullResponse() - Execute and return the full response
ReadManyRequest	QueryRequest, ScanRequest	exec() - Execute and return requested items execCount() - Execute and return the count of the number of items found execSingle() - Execute and return a single item
WriteRequest	DeleteRequest, PutRequest, UpdateRequest	exec() - Execute and return requested attributes
GetRequest	None	exec() - Execute and return the requested item