Posts tagged with '.net core'

This is a repost that originally appeared on the Couchbase Blog: C# Tuples: New C# 7 language feature.

C# tuples are a new feature of C# 7. I’m going to show you the basics of how C# tuples work. I’m also going to mix in a little Couchbase to show tuples in action. However, if you don’t want to install Couchbase just to play around with tuples, don’t worry, you will still be able to follow along.

Note: If you’ve been using C# for a while, you might remember the Tuple Class that was introduced in .NET 4. That class still exists, but it is not the same thing as the new tuple feature of C#.

What are C# tuples?

A "tuple" is a name for a mathematical concept that is just a list of elements. In the LISP family of languages, coding is built almost entirely around the idea that everything is a list. C# once again borrows the kernel of an idea from the functional programming world and integrates it into a non-functional language. So, we get C# tuples (check out the original C# tuple proposal by Mads Torgersen for more details and background).

Remember anonymous types?

But, to make it simple, let’s consider something you may already be familiar with in C#, an anonymous type. To review, you can instantiate a new object without specifying a type:

var myObject = new { Foo = "bar", Baz = 123 };

Behind the scenes, there actually is a type that inherits from the base Object type, but generally speaking, we only deal with the object, not its type.

Additionally, I can’t return an anonymous type from a method, or pass an anonymous type as a parameter without losing the type information in the process.

private object GetAnonymousObject()
{
    return new {Foo = "bar", Baz = 123};
}

private void AnotherMethod()
{
    var obj = GetAnonymousObject();
    Console.WriteLine(obj.Foo); // compiler error :(
}

They are useful, certainly, but I generally refer to these as anonymous objects as I use them, for these reasons.

What’s this got to do with C# tuples?

I think of C# tuples as richer anonymous types. They are a way to create a "class" on the fly without actually defining a class. The syntax for tuples is to simply put parenthesis around a comma separated list of types and names. A tuple literal is just a comma separated list of literals also surrounded by parenthesis. For instance:

(string FirstName, string LastName) myTuple = ("Matt", "Groves");

Console.WriteLine(myTuple.FirstName); // no compiler error :)
Console.WriteLine(myTuple.LastName);  // no compiler error :)

Note: Right now I’m preferring PascalCase for tuple properties. I don’t know if that’s the official guideline or not, but it "feels" right to me.

C# tuples in action

I put tuples to work in a simple console app that interacts with Couchbase.

I created a BucketHelper class that is a very simple facade over the normal Couchbase IBucket. This class has two methods: one to get a document by key and return a tuple, and one to insert a tuple as a document.

public class BucketHelper
{
    private readonly IBucket _bucket;

    public BucketHelper(IBucket bucket)
    {
        _bucket = bucket;
    }

    public (string Key, T obj) GetTuple<T>(string key)
    {
        var doc = _bucket.Get<T>(key);
        return (doc.Id, doc.Value);
    }

    public void InsertTuple<T>((string Key, T obj) tuple)
    {
        _bucket.Insert(new Document<T>
        {
            Id = tuple.Key,
            Content = tuple.obj
        });
    }
}

To instantiate this helper, you just need to pass an IBucket into the constructor.

Tuple as a return type

You can then use the GetTuple method to get a document out of Couchbase as a tuple.

var bucketHelper = new BucketHelper(bucket);

(string key, Film film) fightClub = bucketHelper.GetTuple<Film>("film-001");

The tuple will consist of a string (the document key) and an object of whatever type you specify. The document content is JSON and will be serialized to a C# object by the .NET SDK.

Also, notice that the name of the tuple properties don’t have to match. I used obj in BucketHelper but I used film when I called GetTuple<Film>. The types do have to match, of course.

Tuple as a parameter type

I can also go the other way and pass a tuple as a parameter to InsertTuple.

string key = Guid.NewGuid().ToString();
Film randomFilm = GenerateRandomFilm();
bucketHelper.InsertTuple((key, randomFilm));

The GenerateRandomFilm method returns a Film object with some random-ish values (check out the GitHub source for details). A tuple of (string, Film) is passed to InsertTuple. The Couchbase .NET SDK takes it from there and inserts a document with the appropriate key/value.

Running the console app, you should get an output that looks something like this:

C# tuples sample console output

Note that the Couchbase .NET SDK at this time doesn’t have any direct tuple support, and it may not ever need it. This code is simply to help demonstrate C# tuples. I would not recommend using the BucketHelper as-is in production.

TUH-ple or TOO-ple?

I seem to remember my professor(s) pronouncing it as "TOO-ple", so that’s what I use. Like the hard-G / soft-G debate of "GIF", I’m sure there are those who think this debate is of the utmost importance and are convinced their pronunciation is the one true way. But, both are acceptable.

If you have questions about tuples, I’d be happy to help. You can also contact me at Twitter @mgroves or email me matthew.groves@couchbase.com.

If you have questions about the Couchbase .NET SDK that I used in this post, please ask away in the Couchbase .NET Forums. Also check out the Couchbase Developer Portal for more information on the .NET SDK and Couchbase in general.

This is a repost that originally appeared on the Couchbase Blog: ASP.NET with NoSQL Workshop.

I delivered an ASP.NET with NoSQL workshop at the recent Indy.Code() conference in Indianapolis. I had a lot of fun at this conference, and I recommend you go next year. If you were unable to attend, don’t worry, because I’ve got the next best thing for you: all the material that I used in my workshop.

ASP.NET Workshop in 4 parts

This workshop contained four main parts:

  • Install a NoSQL database (Couchbase Server)

  • Interact with Couchbase Server (using both the Web Console and the .NET (or .NET Core) SDK)

  • Create a RESTful API using ASP.NET (or ASP.NET Core) WebAPI

  • Consume the RESTful API with an Angular frontend

Try it yourself

If you’d like to try it yourself, the ASP.NET with NoSQL Workshop materials are available on GitHub. Each part of the workshop contains a PPT and PDF file for you to follow along. Also, the "completed" version of each workshop is available.

If you get stuck or have any questions, please ask away in the Couchbase .NET Forums. Also check out the Couchbase Developer Portal for more information on the .NET SDK and Couchbase in general.

You can also contact me at Twitter @mgroves.

Bill Wagner is writing .NET Core documentation.

Show Notes:

Bill Wagner is on Twitter

Want to be on the next episode? You can! All you need is the willingness to talk about something technical.

Theme music is "Crosscutting Concerns" by The Dirty Truckers, check out their music on Amazon or iTunes.

This is a repost that originally appeared on the Couchbase Blog: .NET Core List, Queue, and Dictionary Data Structures backed by Couchbase.

The addition of the sub-document API to Couchbase 4.5 has paved the way for efficient data structure support in Couchbase.

In this blog post, I’m going to show a demo of three types of data structures you can use with the Couchbase .NET SDK:

  • List - a list of objects, basically a List<T> backed by Couchbase

  • Queue - a queue of objects, basically a Queue<T> backed by Couchbase

  • Dictionary - a dictionary of objects, basically a Dictionary<K,T> backed by Couchbase

I’ll also discuss a little bit how this works behind the scenes.

You can play along at home if you like. The source code for this blog is available on GitHub, and Couchbase Server is free to download (developer previews of version 5 are currently available monthly).

List

A List<T> is a .NET data structure that is held in memory. With the data structures provided by the Couchbase .NET SDK, you can store it in a Couchbase document.

To create a Couchbase-backed List:

var list = new CouchbaseList<dynamic>(bucket, "myList");

The string "myList" corresponds to the key for the document that will contain the list. When using CouchbaseList<T>, a single document with that key will be created (if one doesn’t exist already). If a document by that key already exists, CouchbaseList will use it.

You can now add/remove items from the list and that will all be persisted to the document. You can also perform other operations like getting a count of the items in the list.

// add 10 objects to the list
for(var i = 0; i < 10; i++)
    list.Add(new { num = i, foo = "bar" + Guid.NewGuid()});

// remove an item from the list by index
list.RemoveAt(5);

// show an item from the list by index
Console.WriteLine("5th item in the list: " + list[5].foo + " / " + list[5].num);

The above code would result in a document with a key "myList" that looks like below. Notice that the item with num of 5 is not listed, because it was removed.

There’s something subtle in the above example that needs to be pointed out. Notice that I used var item = list[5]; and then item.foo and item.num in the WriteLine. If I used list[5].foo and list[5].num directly, that would result in two different subdocument calls to Couchbase. Not only is this less than optimal efficiency, but it’s possible for the values to change between the two calls.

[
  {
    "num": 0,
    "foo": "bara1fd74ee-a790-4a0f-843c-abe449cb8b1d"
  },
  {
    "num": 1,
    "foo": "bardc1d8f9a-4e93-46f9-b8ae-ec036743869e"
  },
  {
    "num": 2,
    "foo": "bar9a60abe9-1e04-4fba-bd1f-f1ec39d69f56"
  },
  {
    "num": 3,
    "foo": "bar9566605b-7abf-4a0c-aa9d-63b98ce86274"
  },
  {
    "num": 4,
    "foo": "bar6261323f-de50-42a7-a8a7-6fcafb356deb"
  },
  {
    "num": 6,
    "foo": "bar13832bcb-2aa0-491a-a01f-1d496f999ffc"
  },

  // ... etc ...
]

Queue

Very similar to List, you can create a Couchbase-backed queue:

var queue = new CouchbaseQueue<dynamic>(bucket, "myQueue");

A queue is stored just like a list. The difference is that the ordering is significant, and this is reflected by the operations you perform on a queue: Enqueue and Dequeue.

for(var i = 0; i < 3; i++)
    queue.Enqueue(new { num = i, foo = "baz" + Guid.NewGuid()});

// dequeue
var item = queue.Dequeue();
Console.WriteLine("item num " + item.num + " was dequeued. There are now " + queue.Count + " items left in the queue.");

The above code would result in a document with a key "myQueue" (see JSON below). Notice there is no object in the array with num "0" because it was dequeued.

[
  {
    "num": 1,
    "foo": "baz64bb62b6-bf23-4e52-b584-d2fa02accce6"
  },
  {
    "num": 2,
    "foo": "baz0a160bd9-aa7b-4c45-9e19-d1a3d982a554"
  }
]

Dictionary

Hopefully you’re seeing a pattern now. To create a dictionary:

var dict = new CouchbaseDictionary<string,dynamic>(bucket, "myDict");

Again, a document will be created with the given key. The operations that can be performed include Add, Remove, and the indexer [] operation.

for(var i = 0; i < 5; i++)
    dict.Add("key" + Guid.NewGuid(), new { num = i, foo = "qux" + Guid.NewGuid()} );

// print out keys in the dictionary
Console.WriteLine("There are " + dict.Keys.Count + " keys in the dictionary.");
foreach(var key in dict.Keys)
    Console.WriteLine("key: " + key + ", value.num: " + dict[key].num);

A dictionary document looks like:

{
  "key5aa2520d-123c-4fca-b444-b0cb8846d46e": {
    "num": 0,
    "foo": "qux93b197dc-f175-4246-a38d-7b080eb9bea0"
  },
  "key55dee298-14c6-4da7-97a8-66c69d7e8a70": {
    "num": 1,
    "foo": "quxa593ee4c-682c-402d-887b-3f09f029e9b6"
  },
  "key3386afcf-7b70-4e4d-b9ae-6defbca33fe7": {
    "num": 2,
    "foo": "qux1259ae94-1008-4e1f-86a1-bfbd0873b09b"
  },
  "key2bc8c451-f125-4282-9fb4-7ea15f4b3168": {
    "num": 3,
    "foo": "qux1b6fb62b-9918-46dc-9a2f-610a55d017ef"
  },
  "key3f7041f3-abd3-49c7-a373-454cbd2ac0fc": {
    "num": 4,
    "foo": "qux0a87655f-197d-4fb2-8a54-b1de6e288de4"
  }
}

A note about C# dynamic: I used dynamic to keep the code samples short and simple. In your application, you are probably better off using a real defined C# type. It all gets serialized to JSON in Couchbase, of course.

Behind the scenes

Before the subdocument API was released in Couchbase Server 4.5, these data structures were possible, of course. The catch was that you would be loading up the entire document, putting it in a list, making changes to the list, and then saving the entire document. If you have large data structures, but are only reading or making changes to a single item, this would often result in wasted time and wasted bandwidth and possibly increased contention.

The subdocument-API (which you can use directly; I covered it in the Sub-document API in Couchbase Server 4.5 with the .NET SDK (revisited) blog post) is used behind the scenes in CouchbaseList, CouchbaseQueue, and CouchbaseDictionary. So when you add an item to a CouchbaseList, for instance, only that item is being sent over the wire, not the entire list.

Some operations will still need to get the entire document. For instance, iterating through a collection using a foreach loop will retrieve the full document. Removing an item from a list will result in the full document being scanned. But if sub-document operations come along in the future to support those actions, the SDK implementations will be updated accordinging.

Summary

These data structures are another tool to help you manage your data. Since they use the sub-document API, they are generally more performant than a whole-document approach. For more detail, check out the Data Structures documentation.

Have questions? Feedback? Need help? Please visit our forums, ping me on Twitter @mgroves, or leave a comment.

J. Tower is answering all my burning questions about .NET and .NET Core

Show Notes:

J. Tower is on Twitter

Want to be on the next episode? You can! All you need is the willingness to talk about something technical.

Theme music is "Crosscutting Concerns" by The Dirty Truckers, check out their music on Amazon or iTunes.

Matthew D. Groves

About the Author

Matthew D. Groves lives in Central Ohio. He works remotely, loves to code, and is a Microsoft MVP.

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