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    1.0.0 • Public • Published

    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.

    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.

    // 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:

    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.

    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

    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.

    // 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 {

    Basic Usage:

    // 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:

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

    Condition Object:

    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);
    {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!!):

    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);


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    • a8m
    • aws
    • aws-dynamodb