flankershark / linqit

LINQ-like functions in JavaScript

linqit

A couple of LINQ-like functions. Truth to be told, it's far away to be a real project and deal with more complicated requirements in the real world. It's just for fun coz I was playing around with JavaScript and Node.js =]

Runtime Environment

node.js
tested on v5.3.0

Samples

Let's say we have a piece of data, it can be either

• object array like JSON object or
• primitve array like numbers

One of the most popular scenarios is to manipulate data by using ways to deal with different business rules, requirements or whatever you name it. However, these can be divided into may be three categories:

• fitering
• sorting and
• joining data

Or I forgot something else, but hope I didn't. Anyway, let's get started.

Let's make some sample data first (Again, primitive array works as well)

var users = [
    {
        id: 1,
        first_name: 'Emily',
        last_name: 'Perri',
        avatar: 'perrie.png'
        // and some fields you like
    }
    
    // ..., and, thousands of records here, aren't there?
    // Your imagination is necessary for that :)
];

You might be familar with LINQ and SQL. Assuming that you know SQL at least. So the following linqit code are equivalent to the SQL statement followed by

console.log(
    linqit()
        .from(users)
        .where(user => user.last_name === 'Perri')
        .orderby((a, b) => (a.id - b.id))
        .select(
            { id: user.id, first_name: user.first_name, avatar: user.avatar }
        )
);

SELECT id, first_name, avatar
    FROM users
    WHERE last_name = 'Perri'
    ORDER BY id ASC
    ;

Of course, each single part can work as a standalone function as well. So it can also be like this:

console.log(
    linqit()
        .from(users)
        .where(user => user.last_name === 'Perri')
        .orderby((a, b) => (a.id - b.id))
);

or

console.log(
    linqit()
        .from(users)
        .where(user => user.last_name === 'Perri')
);

even

console.log(
    linqit()
        .from(users)
);

With operator .select(), columns in result set can be reordered even renamed

console.log(
    linqit()
        .from(users)
        .where(user => util.count(user.last_name) > 6)
        .orderby((a, b) => (a.id - b.id))
        .select(
            user => (
                {   // reorder, rename your data ('work_email', a new alias given here, like SQL keyword AS)
                    work_email: user.email,
                    last_name: user.last_name,
                    first_name: user.first_name,
                    avatar: user.avatar,
                    id: user.id
                }
            )
        )
);

TODO

A few more features might be put on the list

1. to join something on something else
2. to group by and handle having part
3. to constrain the number of records, by using a series of functions: limit(cursor, offset), limit(n), all()
4. a few of SQL-related functions, such as count() [done], max(), min(), sum(), avg()

Operators .join(), .on(), and .as() might be like this

linqit()
    .from(users).as(a)
    .join(following).as(b).on((a, b) => (a.id === b.id))
    .join(activities).as(c).on((a, c) => (a.id === c.id))

For sure that everything can be on put the same line as expected

linqit().from(users).where(user => user.id < 5).orderby((a, b) => (a.id - b.id)).select(user => ({ id: user.id, first_name: user.first_name }));

And

Hope it's gonna be a real project soon :)

console.log('Happy New Years & Have fun :)');

//:)~

References

1. Microsoft LINQ
   https://msdn.microsoft.com/en-us/library/bb397926.aspx
2. [TODO]