simple-dynamo

Abstraction of Amazons Dynamo DB Service. Usage of AWS DynamoDB incredible simple.

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simple-dynamo

is a abstraction layer to Jed Schmidt's dynamo Node.js driver.

Build Status Travis currently fails because the credentials are no longer vaild

It provides a absolute simple JSON-CRUD Interface without any knowledge of Dynamos specialties.

A special feature is the combineTableTo options for tables. It adds the ability to combine multiple models into one Dymamo-table, but use them separately in your application. So you have to pay only one throughput capacity.

Need a offline version of Dynamo? mysql-dynamo is a solution to use the same interface of this simple-dynamo module with a MySQL database.

Written in coffee-script

INFO: all examples are written in coffee-script

Install

  npm install simple-dynamo

Connection and Table

Initialize

first you have to define the connection and table attributes and get an instance of the simple-dynamo interface.

new SimpleDynamo( connectionSettings, tables )

connection Settings

  • accessKeyId : Your AWS access key id
  • secretAccessKey : Your AWS secret access key
  • region : The region your Dynamo-Tables will be placed

table Definition

An Object of Tables.
The key you are using will be the key to get the table object.

Every object can have the following keys:

  • name : ( String required )
    Tablename for AWS
  • hashKey : ( String required )
    The hash key name of your ids/hashes
  • hashKeyType : ( String optional: default = S )
    The type of the hashKey. Possible values are: S = String and N = Numeric
  • rangeKey: ( String optional )
    The range key name of your range attribute. If not defined the table will be generated without the range methods
  • rangeKeyType: ( String optional: default = N )
    The type of the rangeKey. Possible values are: S = String and N = Numeric
  • fnCreateHash: ( Function optional: default = new UUID )
    Method to generate a custom hash key.
  • defaultfields: ( Array optional )
    List of fields to return as default. If nothing is defined all fields will be received. You always can overwrite this using options.fields.
  • combineTableTo: ( String optional ) Option to combine multiple models into one dynamo-table. Makes sense if you want to pay only one table. Combinations are not allowed for tables of different types ( Hash-table and HashRange-table ) and you have to use the same hashKey and rangeKey. The module will handle all interactions with the models transparent, so you only have to define this option.
    Note: If you use this feature and predefine the id/hash you have to add the name of the table in front of every id/hash.
  • overwriteExistingHash: ( Boolean optional: default = false )
    Overwrite a item on create of an existing hash.
  • consistent: ( Boolean optional: default = false )
    Do consistend reads on table.get() and table.find() as default
    Method Arguments
    • attributes: The given attributes on create
    • cb: Callback method to pass the custom generates id/hash. cb( "my-special-hash" )
  • fnCreateRange: ( Function optional: default = current Timestamp )
    Method to generate a custom range key.
    Method Arguments
    • attributes: The given attributes on create
    • cb: Callback method to pass the custom generates id/hash. cb( "my-special-range" )
  • attributes: ( Array of Objects required )
    An array of attribute Objects. Which will be validated
    Attributes keys
    • key: ( String required )
      Column/Attribute name/key
    • type: ( String required )
      Datatype. possible values are string = String, number = Numeric and array = Array/Set of Strings
    • required: ( Boolean optional: default = false )
      Validate the attribute to be required. ( Not implemented yet ! )

Example

# import module
SimpleDynamo = require "simple-dynamo"

# define connection settings
connectionSettings =
    accessKeyId: "-"
    secretAccessKey: "-"
    region: "eu-west-1"

# define tables
tables = 
    "Users":
        name: "users"
        hashKey: "id"

        attributes: [
            { key: "name", type: "string", required: true }
            { key: "email", type: "string" }
        ]

    "Todos":
        name: "todos"
        hashKey: "id"
        rangeKey: "_t"
        rangeKeyType: "N"

        fnCreateHash: ( attributes, cb )=>
            cb( attributes.user_id )
            return

        attributes: [
            { key: "title", type: "string", required: true }
            { key: "done", type: "number" }
        ]

    # example for a combined table usage
    "Combined1":
        name: "c1"
        hashKey:  "id"
        combineTableTo: "combined_hash"

        attributes: [
            { key: "title", type: "string", required: true }
        ]

    "Combined2":
        name: "c2"
        hashKey:  "id"
        combineTableTo: "combined_hash"

        attributes: [
            { key: "title", type: "string", required: true }
        ]

# create instance
sdManager = new SimpleDynamo( connectionSettings, tables )

# connect
sdManager.connect ( err )->
    console.log( "simple-dynamo ready to use" )

First connect to AWS

The module has to know about the existing AWS tables so you have to read them first.
If you do not run .connect() the module will throw an error everytime

Manager.connect( fnCallback ) Arguments :

  • fnCallback: ( Function required )
    Callback method. Single arguments on return is the error object. On success the error is null

Example

sdManager.connect ( err )->
    if err
        console.error( "connect ERROR", err )
    else
        console.log( "simple-dynamo ready to use" )

Create all tables

to create all missing tables just call .createAll().

This is not necessary if you know the tables has been created in the past.

Note! The generating of tables could take a few Minutes

Manager.generateAll( fnCallback ) Arguments :

  • fnCallback: ( Function required )
    Callback method. Single arguments on return is the error object. On success the error is null

Example

sdManager.generateAll ( err )->
    if err
        console.error( "connect ERROR", err )
    else
        console.log( "simple-dynamo ready to use" )

Get a table instance

To interact with a table you have to retrieve the table object. It's defined in the table-definitions

Manager.get( 'tableName' ) Arguments :

  • tableName: ( String required )
    Method to retrieve the instance of a table object.

Example

tblTodos = sdManager.get( 'Todos' )

Destroy a table

destroy table at AWS. This removes the table from AWS will all the data

Table.destroy( fnCallback ) Arguments :

  • fnCallback: ( Function required )
    Callback method.
    Method Arguments
    • err: Usually null. On an error a object with error and msg

Example

tblTodos.del ( err )->
    if err
        console.error( "destroy ERROR", err )
    else
        console.log( "table destroyed" )

Item handling

Write a new item (INSERT)

Create a new item in a select table. You can also add some attributes not defined in the table-definition, which will be saved, too.

Table.set( data, options, fnCallback ) Arguments :

  • data: ( Object required )
    The data to save. You can define the hash and/or range key. If not the module will generate a hash/range automatically.
    Note: If the used table uses the combined feature and you define the hash-key it's necessary to add the name out of the table-config in front of every hash.
  • options: ( Object optional )
    • fields: ( Array ) An array of fields to receive
    • overwriteExistingHash: ( Boolean optional: default = [tableConfig.overwriteExistingHash] ) Overwrite a item it already exists.
  • fnCallback: ( Function required )
    Callback method.
    Method Arguments
    • err: Usually null. On an error a object with error and msg
    • item: the save item as simple object

Example

data = 
    title: "My First Todo"
    done: 0
    aditionalData: "Foo bar"

tblTodos.set data, ( err, todo )->
    if err
        console.error( "insert ERROR", err )
    else
        console.log( todo )

Get a item (GET)

Get an existing element by id/hash

Table.get( id, fnCallback ) Arguments :

  • id: ( String|Number|Array required )
    The id of an element. If the used table is a range table you have to use an array [hash,range] as combined id. Otherwise you will get an error.
  • options: ( Object optional )
    • fields: ( Array ) An array of fields to receive. If nothing is defined all fields are returned.
    • consistent: ( Boolean optional: default = [tableConfig.consistent] ) do a consitent read
  • fnCallback: ( Function required )
    Callback method.
    Method Arguments
    • err: Usually null. On an error a object with error and msg
    • item: the database item as simple object. If not found null

Example

tblTodos.get 'myTodoId', ( err, todo )->
    if err
        console.error( "get ERROR", err )
    else
        console.log( todo )
tblRangeTodos.get [ 'myHash', 'myRange' ], ( err, todo )->
    if err
        console.error( "get ERROR", err )
    else
        console.log( todo )

Get many items (MGET)

Get an many existing elements by id/hash in one request

Table.mget( [ id1, id2, .. ], options, fnCallback ) Arguments :

  • ids: ( Array required )
    An array of id of an elements. If the used table is a range table you have to use an array of arrays [hash,range] as combined id. Otherwise you will get an error.
  • options: ( Object optional )
    • fields: ( Array ) An array of fields to receive. If nothing is defined all fields are returned.
  • fnCallback: ( Function required )
    Callback method.
    Method Arguments
    • err: Usually null. On an error a object with error and msg
    • items: the database items as a array of simple objects. Only existing items will be received.

Example

tblTodos.mget [ 'myTodoIdA', 'myTodoIdB' ], ( err, todos )->
    if err
        console.error( "get ERROR", err )
    else
        console.log( todos )
tblRangeTodos.mget [ [ 'myHash', 1 ], [ 'myHash', 2 ] ], ( err, todos )->
    if err
        console.error( "get ERROR", err )
    else
        console.log( todos )

Update an item (UPDATE)

update an existing item.
To remove a attribute you have to set the value to null

Table.set( id, data, options, fnCallback ) Arguments :

  • id: ( String|Number|Array required )
    The id of an element. If the used table is a range table you have to use an array [hash,range] as combined id. Otherwise you will get an error.
  • data: ( Object required )
    The data to update. You can redefine the range key. If you pass the hash key it will be ignored
  • options: ( Object optional )
    For update you can define some options.
    • fields: ( Array ) An array of fields to receive
    • conditionals ( Object ) A query object to define a conditional. Only {"==": value}, {"==": null}, and {"!=": null} are allowed. How to build? … have a look at Jed's Predicates
  • fnCallback: ( Function required )
    Callback method.
    Method Arguments
    • err: Usually null. On an error a object with error and msg
    • item: the database item as simple object. If not found null

Example

data = 
    title: "My First Update"
    done: 1

tblTodos.set 'myTodoId', data, ( err, todo )->
    if err
        console.error( "update ERROR", err )
    else
        # note. the key 'aditionalData' will be gone
        console.log( todo )

Delete an item (DELETE)

delete an item by id/hash

Table.del( id, fnCallback ) Arguments :

  • id: ( String|Number|Array required )
    The id of an element. If the used table is a range table you have to use an array [hash,range] as combined id. Otherwise you will get an error.
  • fnCallback: ( Function required )
    Callback method.
    Method Arguments
    • err: Usually null. On an error a object with error and msg

Example

tblTodos.del 'myTodoId', ( err )->
    if err
        console.error( "delete ERROR", err )
    else
        console.log( "delete done" )

Query a table (FIND)

run a query on a table. The module automatically trys to do a Dynamo.db scan or Dynamo query.

Table.find( query, startAt, options, fnCallback ) Arguments :

  • query: ( Object : default = {} all )
    A query object. How to build … have a look at Jed's Predicates
  • startAt: ( String|Number|Array optional )
    To realize a paging you can define a startAt. Usually the last item of a list. If you define startAt with the last item of the previous find you get the next collection of items without the given startAt item.
    If the used table is a range table you have to use an array [hash,range] as combined startAt. Otherwise you will get an error.
  • options: ( Object optional )
    • fields: ( Array ) An array of fields to receive
    • limit: ( Number ) Define the max. items to return
    • forward: ( Boolean default = true ) define the direction acs or desc for range querys.
    • consistent: ( Boolean optional: default = [tableConfig.consistent] ) do a consitent read.
      Note! This is only availible for real query's through range-tables. This means if you query by hash and range ( e.g. Advanced Examples )
  • fnCallback: ( Function required )
    Callback method.
    Method Arguments
    • err: Usually null. On an error a object with error and msg
    • items: an array of objects found

Example

tblTodos.find {}, ( err, items )->
    if err
        console.error( "delete ERROR", err )
    else
        console.log( "all existend items", items )

Advanced Examples

# create a query to read all todos from last hour
_query = 
    id: { "!=": null }
    _t: { "<": ( Date.now() - ( 1000 * 60 * 60 ) ) }

tblTodos.find , ( err, items )->
    if err
        console.error( "delete ERROR", err )
    else
        console.log( "found items", items )
# read 4 todos from last hour beginning starting with a known id
_query = 
    id: { "!=": null }
    _t: { "<": ( Date.now() - ( 1000 * 60 * 60 ) ) }

_startAt = "myid_todoItem12"

_options = { "limit": 4, "fields": [ "id", "_t", "title" ] }

tblTodos.find _query, _startAt, _options, ( err, items )->
    if err
        console.error( "delete ERROR", err )
    else
        console.log( "4 found items", items )

Working with sets

Dynamo has the ability to work with sets. That means you can save a Set of Strings as an Array.
During an update you have the ability to add or remove a single value out of the set. Or you can reset the whole set.

But you can only perform one action per key and you obnly can use the functionalty if defined through the table-definition ( type:"array" ).

Existing values will be ignored.

The following key variants are availible:

  • "key":[ "a", "b", "c" ]': Resets the whole value of the key
  • "key":{ "$add": [ "d", "e" ] }: Add some values to the set
  • "key":{ "$rem": [ "a", "b" ] }: remove some values
  • "key":{ "$reset": [ "x", "y" ] }: reset the whole value. Same as "key":[ "x", "y" ]'
  • "key":{ "$add": "d"}: Add a single value to the set
  • "key":{ "$rem": "a" }: remove a single value
  • "key":{ "$reset": "y" }: reset the whole set to a single value. Same as "key":[ "y" ]'

Examples

# Source "key: [ "a", "b", "c" ]"

data = 
    key: [ "x", "y", "z" ]

tblSets.set 'mySetsId', data, ( err, setData )->
    # Result "key: [ "x", "y", "z" ]"
    console.log( setData )
# Source "key: [ "a", "b", "c" ]"

data = 
    key: { "$add": [ "a", "d", "e" ] }

tblSets.set 'mySetsId', data, ( err, setData )->
    # Result "key: [ "a", "b", "c", "d", "e" ]"
    console.log( setData )
# Source "key: [ "a", "b", "c" ]"

data = 
    key: { "$rem": [ "a", "b", "x" ] }

tblSets.set 'mySetsId', data, ( err, setData )->
    # Result "key: [ "c" ]"
    console.log( setData )
# Source "key: [ "a", "b", "c" ]"

data = 
    key: { "$reset": [ "x", "y", "z" ] }

tblSets.set 'mySetsId', data, ( err, setData )->
    # Result "key: [ "x", "y", "z" ]"
    console.log( setData )

Events

To provide a API to react on different events you can listen to a bunch of events.

Manager Events

  • new-table: Table object initialized and ready to use. This means only the client model is ready. Eventually you have to create the table first.
    Event Arguments
    • name: the name og the table, like you would use with `Manager.get()
    • Table: the Table object
  • table-generated: Fired after all a new tables has been generated. Event Arguments
    • Meta: the tables meta-data
  • all-tables-generated: Fired after all tables are generated.

Table Events

  • create-status: fired on table create.
    Event Arguments
    • status: describes the state of table creation. Possible values are: already-active, waiting, active
  • get: fired after a table.get.
    Event Arguments
    • item: the item
  • get-empty: fired after a table.get with an empty result.
  • mget: fired after a table.mget.
    Event Arguments
    • items: the items
  • mget-empty: fired after a table.mget with no results.
  • create: fired after a item has been created.
    Event Arguments
    • item: the created item
  • update: fired after a item has been updated.
    Event Arguments
    • item_new: the item after the update
  • delete: fired after a item has been deleted.
    Event Arguments
    • item_old: the item before the delete

Changelogs

0.3.11

  • correct handling of a string predicate with filter for null

0.3.10

  • toString radix bugfix

0.3.9

  • removed log output

0.3.8

  • Added option to be able to increment a numeric by n. To use this you can set the field e.g. to table_key: { "$add": 1 }

0.3.7

  • Bugfix for correct handling of BETWEEN predicates

0.3.6

  • Added conditionals to delete

0.3.5

  • fixed #5: fixed bug for set empty array on create
  • fixed #9: fixed bug for null on fliedtype `number

0.3.4

  • fixed #7: bug fix set a attribute to null will lead to a removal. For a string attribute a set to an empty string will also lead to a attribute removal

0.3.3

  • bug fix set handling by passing empty arrays
  • feature #6: added defaultfields option to table-config.

0.3.2

  • added implicit set detection for update by testing for a object with one of the keys $add, $rem and $reset

0.3.1

  • bugfix option.forward on find.()

0.3.0

  • changed update behavior. Now there is not get before set.
  • Event update, no longer with new and old value. Just the new value. This is a victim to the removal of get before set.
  • added option conditionals to update. So you can define conditions to your update
  • removed option removeMissing. Now you have to set a attribute to null to remove it.
  • added forward option to .find() to define the direction of a range query

Todos

  • handle throughput exceedwith a retry
  • better check of the given config-data
  • check for node.js 0.8.0

Work in progress

simple-dynamo is work in progress. Your ideas, suggestions etc. are very welcome.

License

(The MIT License)

Copyright (c) 2010 TCS <dev (at) tcs.de>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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