@jitterbit/npdynamodb/lib/dialects/2012-08-10/feature.js

A Node.js Simple Query Builder and ORM for AWS DynamoDB.

'use strict';

var _ = require('lodash');
var util = require('util');
var EventEmitter = require('events').EventEmitter;

var utils = require('../../utils');
var api = require('./api');

var clientPools = {};

var extraOperators = {
  where: [
    'BEGINS_WITH',
    'BETWEEN'
  ],
  filter: [
    'BETWEEN',
    'BEGINS_WITH',
    'NOT_NULL',
    'NULL',
    'CONTAINS',
    'NOT_CONTAINS',
    'IN'
  ]
};

var availableOperators = api.availableOperators.concat(extraOperators.filter);

var parameterBuilder = {};

parameterBuilder.createTable = parameterBuilder.deleteTable = function(feature){
  return { conditions: feature.params };
};

parameterBuilder.deleteItem = parameterBuilder.getItem = parameterBuilder.updateItem = function(feature){
  var cond = utils.collectionFlatten(_.map(feature.whereConditions, function(param){
    return utils.newObject(param.key, param.values[0]);
  }));

  return { conditions: { Key: cond } };
};

parameterBuilder.query = function(feature){
  var obj = {};

  obj.KeyConditions = feature.toDocClientConditon(feature.whereConditions);

  if(!_.isEmpty(feature.filterConditions)){
    obj.QueryFilter = feature.toDocClientConditon(feature.filterConditions);
  }

  return { conditions: obj };
};

parameterBuilder.putItem = function(feature){
  if(_.isArray(feature.params)) {
    var items = feature.params.map(function(item){
      return {PutRequest: { Item: item } };
    });

    var tableName = feature.conditions.TableName;

    return {
      beforeQuery: function(){
        this.nonTable();
      },
      nextThen: 'batchWriteItem',
      conditions: {
        RequestItems: utils.newObject(tableName, items)
      }
    };

  }else{
    return {conditions: { Item: feature.params } };
  }
};

parameterBuilder.batchGetItem = function(feature){
  var requestItems = {};
  requestItems[feature.conditions.TableName] = {
    Keys: feature.whereInConditions
  };

  ['AttributesToGet', 'ConsistentRead', 'ProjectionExpression', 'ExpressionAttributeNames'].forEach(function(attr){
    if(feature.conditions[attr]){
      requestItems[feature.conditions.TableName][attr] = feature.conditions[attr];
      delete feature.conditions[attr];
    }
  });

  return {
    beforeQuery: function(){
      this.nonTable();
    },
    conditions: {
      RequestItems : requestItems
    }
  };
};

function Feature(clients){
  EventEmitter.call(this);

  this.client = clients.dynamodb;

  this.promisifidRawClient = clients.promisifidRawClient;

  this.nextThen = undefined;

  this.params = {};

  this.whereConditions = [];

  this.whereInConditions = [];

  this.filterConditions = [];

  this.conditions = {};

  this.schema = {};
}

util.inherits(Feature, EventEmitter);

_.each(api.operations, function(spec, method){
  _.each(spec.input.members, function(typeSpec, member){
    Feature.prototype[_.camelCase(member)] = function(params){
      this.conditions[member] = params;
      return this;
    };
  });
});

_.each(api.transformFunctionMap, function(oldM, newM){
  Feature.prototype[newM] = function(params){
    this.nextThen = oldM;
    this.params = params;
  };
});

Feature.prototype.select = function(){
  this.attributesToGet(_.toArray(arguments));
};

Feature.prototype.table = function(tableName){
  this.tableName(tableName);
};

Feature.prototype.count = function(){
  this.conditions.Select = 'COUNT';
  this.nextThen = 'query';
};

Feature.prototype.offset = function(exclusiveStartKey){
  this.exclusiveStartKey(exclusiveStartKey);
};

Feature.prototype.whereIn = function(keys, values){
  //items[this.conditions.TableName] = {};
  if(!_.isArray(keys)) {
    keys = [keys];
  }
  this.whereInConditions = this.whereInConditions.concat(values.map(function(val){
    if(!_.isArray(val)){
      val = [val];
    }

    if(val.length !== keys.length) {
      throw new Error('the length of key and value did not match.');
    }
    return utils.pairEach(keys, val);
  }));
  this.nextThen = 'batchGetItem';
};

_.each([
  'filter',
  'where'
], function(operator){

  Feature.prototype[operator] = function(){
    addConditions.apply(this, [operator].concat(_.toArray(arguments)));
    return this;
  };

  _.each(extraOperators[operator], function(_operator){
    Feature.prototype[operator + utils.toPascalCase(_operator.toLowerCase())] = function(){
      var args = _.toArray(arguments);
      var newArgs = [operator, args.shift(), _operator].concat(args);
      addConditions.apply(this, newArgs);
      return this;
    };
  });
});

function addConditions(){
  var args = _.toArray(arguments);
  var col = args[1], op = args[2], val = args[3];
  if(!_.includes(availableOperators, op)){
    val = op;
    op = '=';
  }

  this[args[0]+'Conditions'].push({
    key: col,
    values: [val].concat(Array.prototype.slice.call(args, 4)),
    operator: op
  });
}

Feature.prototype.toDocClientConditon = function(conditions){
  var self = this;
  return conditions.map(function(cond){
    var args = [
      cond.key,
      api.transformOperatorMap[cond.operator] || cond.operator
    ].concat(cond.values);
    return self.client.Condition.apply(null, args);
  });
};

Feature.prototype.set = function(key, action, value){
  if(!this.conditions.AttributeUpdates) {
    this.conditions.AttributeUpdates = {};
  }

  this.conditions.AttributeUpdates[key] = {
    Action: action,
    Value: value
  };

  return this;
};

Feature.prototype.asc = function(){
  this.scanIndexForward(true);
};

Feature.prototype.desc = function(){
  this.scanIndexForward(false);
};

Feature.prototype.nonTable = function(){
  this.conditions = _.omit(this.conditions, 'TableName');
};

Feature.prototype.normalizationRawResponse = function(data){
  // query operation
  if(data.Items) {
    return data.Items;
  }

  // getItem operation
  if(data.Item) {
    return data.Item;
  }

  // batchGetItem Operation
  if(data.Responses && data.Responses[this.conditions.TableName]) {
    return data.Responses[this.conditions.TableName].reverse();
  }
};

Feature.prototype.buildQuery = function(){
  var nextThen = this.nextThen || 'query';
  var self = this;

  if(this.whereInConditions.length > 0 && this.whereConditions.length > 0) {
    throw new Error('Can not specify the parameters of batchGetImte and Query operation at the same time');
  }

  function supplement(builder){
    if(!builder) return undefined;

    return function(){
      var result = builder(self);
      if(!result.beforeQuery) result.beforeQuery = function(){};
      if(!result.nextThen) result.nextThen = nextThen;

      return result;
    };
  }

  var builder = supplement(parameterBuilder[nextThen]) || function(){
    return {
      beforeQuery: function(){},
      conditions: {},
      nextThen: nextThen
    };
  };

  var built = builder();
  built.beforeQuery.call(this);

  this.nextThen = built.nextThen;
  this.conditions = _.extend(this.conditions, built.conditions);

  return {
    params: this.conditions,
    method: this.nextThen
  };
};


module.exports = Feature;