DynamoDB Document SDK

This SDK abstracts away the typing of attribute values in the low level SDK in order to provide a simpler developing experience.
JS datatypes like string or number can be passed directly into DynamoDB requests and the wrapping will be handled for you; similarly for responses, datatypes will be unwrapped.

For those DynamoDB types that do not have direct mappings to JS datatypes, a wrapper Object is provided to handle type ambiguities (i.e. StrSet, NumSet, BinSet).

Lastly, a Condition Object is being introduced to simplify the use of the KeyCondition and Expected portion of the request params.
Note: Condition Object serves to simplify previous api (NOT new expressions)

Getting Started

In order to instantiate the client, you still need the AWS JS SDK to store your region/credentials.

`` javascript
var AWS = require("aws-sdk");
var DOC = require("dynamodb-doc");

AWS.config.update({region: "us-west-1"});

var docClient = new DOC.DynamoDB();
`

Alternatively if you already have the existing DynamoDB Client, you can pass it in order to instantiate the client.

` javascript
// assumes AWS.config is set up already
var awsClient = AWS.DynamoDB();
var docClient = new DOC.DynamoDB(awsClient);
`

After this, you can make requests and receive responses with JS datatypes!

JS datatypes that can be used in place of DynamoDB Datatypes:

|Javascript| DynamoDB |
|:--------:|:----------:|
|string | S |
|number | N |
|boolean | BOOL |
|null | NULL |
|array | L |
|object | M |


For Sets, the client will provide object for you:

` javascript
docClient.Set(["a", "b", "c"], "S")
`

Refer to the Basic Usage and Nested DataTypes and More sections down below to see examples of the updated API.

In addition, the SDK also introduces a special kind of Object in order to simplify conditions.

` javascript
docClient.Condition(key, operator, val1, val2)
`

Refer to the section down below on Condition Objects to see an example of the usage.

NOTE: To build the node js files for the browser yourself, run

` bash
npm install; uglifyjs lib/* | sed 's/\"use strict\";//' > dynamodb-doc.min.js


sed portion is optional depending on your use case


`

For each example assume we have these variables available to us.

` javascript
// Basic Client creation
AWS.config.update({ / ...your config... / });
docClient = new DOC.DynamoDB();

// Basic Callback
var pfunc = function(err, data) {
if (err) {
console.log(err, err.stack);
} else {
console.log(data);
}
}
`

Basic Usage:

` javascript
// Basic Scalar Datatypes
var params = {};
params.TableName = "Users";
params.Item = {UserId : "John",
Age : 21,
Pic : docClient.StrToBin("someURI")};

docClient.putItem(params, pfunc);

params = {};
params.TableName = "Users";
params.Key = {UserId : "John"}

docClient.getItem(params, pfunc);

/* Response
{Item: {UserId : "John",
Age : 21,
Pic : Bin}}
*/
`

NOTE: StrToBin returns either a Buffer for NodeJS or Uint8Array for the browser.

Nested DataTypes and More:

` javascript
var params = {};
params.TableName = "Shopping Cart";

// Compatible is a Map of Part to List of PartId's
// OnSale is a BOOL type
// Discount is a NULL type
params.Item = {PartId : "CPU1",
OnSale : false,
Discount : null,
Compatible : {Motherboards : ["MB1", "MB2"],
RAM : ["RAM1"]}};

docClient.putItem(params, pfunc);

params = {};
params.Key = {PartId : "CPU1"};
params.TableName = "Shopping Cart";

docClient.getItem(params, pfunc);

/*Response
{Item: {PartId : "CPU1",
OnSale : false,
Discount : null,
Compatible : {Motherboards : ["MB1", "MB2"],
RAM : ["RAM1"]}}};
*/
`

Condition Object:

` javascript
var params = {};
params.TableName = "Houses";

// Note: This is a query on the Key Schema of the table.
// For queries on secondary indexes, specify params.IndexName = "index-name"

// use an array of Condition Objects for multiple conditions
params.KeyConditions = [docClient.Condition("HouseId", "NOT_NULL"),
docClient.Condition("YearBuilt", "GT", 2000)];

// use a Condition Object for just a single condition
params.QueryFilter = docClient.Condition("Price", "BETWEEN", 0, 900000);

docClient.query(params, pfunc);

/*Reponse
{Count: 3,
Items: [ { HouseId : "123 amzn way",
YearBuilt : 2001,
Price : 450000},
{ HouseId : "321 dynamo st",
YearBuilt : 2012,
Price : 100000},
{ HouseId : "213 JS ave",
YearBuilt : 2014,
Price : 1}],
ScannedCount: 3}
*/
`

Expressions (NEW!!):

` javascript
var params = {};
params.TableName = "SomeTable";
params.Key = {Some : "Key"};

// Use the #(variable) to substitute in place of attribute Names
// Use the :(variable) to subsitute in place of attribute Values
params.UpdateExpression = "set #a = :x + :y";
params.ConditionExpression = "#a < :MAX and Price = :correct";
params.ExpressionAttributeNames = {"#a" : "Description"};
params.ExpressionAttributeValues = {":x" : 20,
":y" : 45,
":MAX" : 100,
":correct" : "is right!!"};

docClient.updateItem(params, pfunc);
``