Dataflow

Dataflow is a library that can be used to represent object data manipulation as a concise, jQuery-style series of function invocations. It supports both synchronous and asynchronous operations so the programming style is the same in both cases.

Example

To illustrate this concept with an example, consider the following:

var names = ["Dedekind", "Riemann", "Cauchy"];
new taiste.DataFlow([
        { test: 123, foo: "bar", users: [0, 2],
            votes: { 0: true, 1: false, 2: true } },
        { test: 456, foo: "barbar", users: [1, 0], votes: { 0: false }}
    ])
    .pluck('users')
        .asyncMapEach(function() {
            _.delay(_.bind(function() {
                this.setData( { name: names[this.data]} );
                this.next();
            }, this), 250);
        }).end()
    .pluck('votes')
        .each(function(value, key) {
            var context = this;
            new taiste.DataFlow(value, undefined, undefined, true)
                .each(function(vote, user) {
                    context.data[key][user] = {
                        vote: vote,
                        user: context.parent.users[key][user]
                    };
                });
        }).end()
    .asyncOperation(
        function() {
            console.log("Running async op");
            _.delay(_.bind(function() {
                this.next();
            }, this), 250);
        })
    .then(function() {
        var context = this;
        _.delay(function() {
            context.next();
        });

        return false;
    })
    .then(function() {
        console.log(this);
    });

The most important methods to understand are then, next, pluck, asyncMap, asyncEach, map, each and mapEach. then adds a new function to the asynchronously executed pqueue. The execution can be made asynchronous by returning false from the then function. The context contains next function that is required to be executed when the operation finishes.

The data is contained in the context's data property, that can be manipulated.

The queue is executed in the order the items are added to it. The pluck function can be used to separate a new "stack item" so that the following functions before end are operating with the plucked data. Pluck also accepts wildcards and nested plucking with * and .. The end can be then used to add the transformed data back to the master object. The root object is always accessible using the root function on the context.

The getJSON-method can be used to add data to the queue.

External requirements

• jQuery
• Underscore.js
• Taiste underscore extensions

Licence

Licenced under MIT:

Copyright (C) 2011 by Taiste Oy

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.