SimpleDB Query Builder

AWS's Node.js SDK doesn't support building SimpleDB select queries and hand writing/concatenating them feels weird, so I wrote this library to allow these queries to be built programatically.

API

There are three classes in this library, Query, Predicate, and Attribute. You probably won't be interacting the Predicate class directly, but instead using it through Attribute.

Query

Class Variables

• Query.ALL
• Query.ITEM_NAME
• Query.COUNT

These are options for Query#select.

Class Methods

• itemName(): creates a itemName() attribute so it doesn't get escaped on serialization.

Methods

• Query#select(param): Sets the attributes to return. param can be Query.ALL, Query.ITEM_NAME, Query.COUNT, a string of attributes (e.g. 'attr1,attr2,...attrN'), or an array of Attributes.
• Query#from(domain:String): Sets the domain to select from.
• Query#where(predicate:Predicate): Sets the where part of the query.
• Query#intersect(predicate:Predicate): Intersects another predicate. Essentially it will be (this INTERSECTION predicate).
• Query#order(order_by:Attribute, desc=false): Order result by order_by.
• Query#limit(take:Number): Limit the number of rows to return.
• Query#to_sql(): Returns to string representation in quasi-SQL format.

Predicate

Class Methods

• Predicate#and(predicate): Logically AND two predicates
• Predicate#or(predicate): Logically OR two predicates
• Predicate#to_sql(): Returns the predicate in quasi-SQL format.

Attribute

Methods

• new Attribute(name:String): Creates a new attribute with the attribute name name
• Attribute#equal(value:String): The equivalent of the SQL predicate name = value
• Similar methods are implemented for:
  • not_equal
  • like
  • not_like
  • gt: Greater than
  • gte: Greater than or equal to
  • lt: Less than
  • lte: Less than or equal to
• between(left:String, right:String): Equivalent of name BETWEEN left AND right
• in(list:Array): Equivalent of name IN (list_item_1, ..., list_item_N)
• is_null(): Equivalent of name IS NULL
• is_not_null()

Example

var builder = require('simpledb-query-builder')
  , attr = builder.attr
  , every = builder.every
  , Query = builder.Query;

var first_name = attr("first_name");
var last_name = attr("last_name");
var grade = attr("grade");

(new Query).select(Query.ALL).from("users").where(first_name.equal("John")).to_sql()
// SELECT * FROM users WHERE first_name = 'John'

var query_one = new Query;
var predicate_one = first_name.equal("John").and(grade.gt("7"))
query_one.select(Query.COUNT).from("users").where(predicate_one).to_sql()
// SELECT COUNT(*) FROM users WHERE first_name = 'John' AND grade > '7'

var query_two = new Query;
var predicate_two = first_name.equal("John").and(grade.gt("7")).intersect(first_name.equal("Joseph").and(grade.lt("8")))
query_two.from("users").where(predicate_two).to_sql()
// SELECT * FROM users WHERE (first_name = 'John' AND grade > '7') INTERSECTION (first_name = 'Joseph' AND grade < '8')