A lightweight Q/Promise-based adapter of the cumbersome node.js dynamodb API
npm install dynamodb-q --save
var dq = require('dynamodb-q')
dq.GetItem(dq.Table('employees').Key('name', 'JohnDoe').Attribs(['department', 'title','salary']))
.then(function(data){
console.log(data);
}, function(reason){
console.log(reason);
}
);
//If any data is retrieved:
//{ department: 'IT', title: 'Engineer', salary: 120000 }
//Otherwise it will look like this:
//[Error: Empty data]
Default region is set to us-west-2 but you can change this by calling:
dq.SetRegion('your-dynamodb-region');
This constructs a table object to be converted into dynamodb params.
From above example:
dq.Table('employees').Key('name', 'JohnDoe').Attribs(['department', 'title','salary']
In plain English:
- For Table named 'employees'
- Where the key called 'name' is equal to 'JohnDoe'
- Get only these attributes : 'department', 'title','salary'
dq.GetItem(dq.Table('employees').Key('name', 'JohnDoe').Attribs(['department', 'title','salary'])).then(...);
dq.UpdateItem(dq.Table('employees').Key('name', 'JohnDoe').AttribUpdates({salary:140000, title:'Senior Engineer'})).then(...);
dq.PutItem(dq.Table('employees').Item({name:'JaneRoe', department:'HR', title:'Recruiter', salary:70000})).then(...);
dq.DeleteItem(dq.Table('employees').Key('name', 'JohnDoe')).then(...);
Since all operations are promises, you can chain them together (callback flattening) like so:
dq.GetItem(dq.Table('Purchases').Key('ID', 1).Attribs(['ProductName', 'Amount']))
.then(function(data){
return [data, dq.GetItem(dq.Table('Stock').Key('ProductName', data.ProductName).Attribs(['Remaining']))];
})
.spread(function(purchaseData, stockData){
return dq.UpdateItem(dq.Table('Stock').Key('ProductName', purchaseData.ProductName).AttribUpdates({Remaining: stockData.Remaining - purchaseData.Amount}));
});
.then(null, function(reason){
console.log('Failed to update stock because ' + reason);
});
For learning how promises can be used you can refer to the Q Library
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