{"id":1817,"date":"2014-12-16T17:46:21","date_gmt":"2014-12-16T17:46:20","guid":{"rendered":"https:\/\/www.couchbase.com\/blog\/?p=1817"},"modified":"2017-05-04T13:31:17","modified_gmt":"2017-05-04T20:31:17","slug":"using-c-domain-objects-define-couchbase-views","status":"publish","type":"post","link":"https:\/\/www.couchbase.com\/blog\/using-c-domain-objects-define-couchbase-views\/","title":{"rendered":"Using C# Domain Objects to Define Couchbase Views"},"content":{"rendered":"

The Couchbase Client Library 1.2-Beta includes a new API for some basic cluster management.\u00a0 There are methods for creating, removing and listing buckets.\u00a0 There are similar methods for managing design documents.\u00a0 These new features are found in the new class CouchbaseCluster<\/em>, under the Couchbase.Management<\/em> namespace.\u00a0 The main benefit of this new API is that it’s now possible to allow your application to create its bucket and set its design documents when it starts up.<\/p>\n

One of the overloads for creating new design documents allows you to specify a Stream<\/em> as the source of the design document.\u00a0 With this version, it’s easy to create design documents from a set of files.\u00a0 You can also just specify a string containing the document.<\/p>\n

I recently had an idea to create a simple command line utility to use these design doc management methods to automate the creation of basic views.\u00a0 The result of this idea is up on GitHub at https:\/\/github.com\/jzablocki\/couchbase-model-views<\/a>.\u00a0 Using this framework, you’ll be able to automate the creation of views simply by decorating your existing model classes with custom attributes.<\/p>\n

Consider a Beer<\/em> class with a properties for Name, Description, Brewery and ABV.<\/p>\n

\n
\n

public<\/span> class<\/span> Beer
\n{<\/span>
\npublic<\/span> string<\/span> Id {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

public<\/span> string<\/span> Name {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

public<\/span> string<\/span> Description {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

public<\/span> float<\/span> ABV {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

public<\/span> string<\/span> Brewery {<\/span> get;<\/span> set;<\/span> }<\/span>
\n}<\/span><\/p>\n<\/div>\n<\/div>\n

This class maps to “beer” documents in your Couchbase bucket.<\/p>\n

\n
{<\/span>
\n“name”<\/span>:<\/span> “Samuel Adams Summer Ale”<\/span>,<\/span>
\n“abv”<\/span>:<\/span> 5.2<\/span>,<\/span>
\n“type”<\/span>:<\/span> “beer”<\/span>,<\/span>
\n“brewery_id”<\/span>:<\/span> “110f04db06”<\/span>,<\/span>
\n“description”<\/span>:<\/span> “Bright and citrusy, brewed with mysterious grains of…
\n}<\/span><\/div>\n<\/div>\n

To achieve this mapping, you’d likely use Newtonsoft<\/em>.Json<\/em>‘s property mapping attributes.<\/p>\n

\n
\n

public<\/span> class<\/span> Beer
\n{<\/span>
\npublic<\/span> string<\/span> Id {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

[<\/span>JsonProperty(<\/span>“name”<\/span>)<\/span>]<\/span>
\npublic<\/span> string<\/span> Name {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

[<\/span>JsonProperty(<\/span>“description”<\/span>)<\/span>]<\/span>
\npublic<\/span> string<\/span> Description {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

[<\/span>JsonProperty(<\/span>“abv”<\/span>)<\/span>]<\/span>
\npublic<\/span> float<\/span> ABV {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

[<\/span>JsonProperty(<\/span>“breweryId”<\/span>)<\/span>]<\/span>
\npublic<\/span> string<\/span> Brewery {<\/span> get;<\/span> set;<\/span> }<\/span>
\n}<\/span><\/p>\n<\/div>\n<\/div>\n

Using two new attributes found in the CouchbaseModelViews.Framework<\/em> project, you could further decorate this class to declare which properties in this class should be indexed by Couchbase Server.\u00a0 These attributes are CouchbaseDesignDocument<\/em> and CouchbaseViewKey<\/em>.<\/p>\n

\n
\n

[<\/span>CouchbaseDesignDoc(<\/span>“beers”<\/span>, “beer”<\/span>)<\/span>]<\/span>
\npublic<\/span> class<\/span> Beer
\n{<\/span>
\npublic<\/span> string<\/span> Id {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

[<\/span>JsonProperty(<\/span>“name”<\/span>)<\/span>]<\/span>
\n[<\/span>CouchbaseViewKey(<\/span>“by_abv_and_name”<\/span>, “name”<\/span>, 1<\/span>)<\/span>]<\/span>
\n[<\/span>CouchbaseViewKey(<\/span>“by_name”<\/span>, “name”<\/span>)<\/span>]<\/span>
\npublic<\/span> string<\/span> Name {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

[<\/span>JsonProperty(<\/span>“description”<\/span>)<\/span>]<\/span>
\npublic<\/span> string<\/span> Description {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

[<\/span>JsonProperty(<\/span>“abv”<\/span>)<\/span>]<\/span>
\n[<\/span>CouchbaseViewKey(<\/span>“by_abv_and_name”<\/span>, “abv”<\/span>, 0<\/span>)<\/span>]<\/span>
\npublic<\/span> float<\/span> ABV {<\/span> get;<\/span> set;<\/span> }<\/span><\/p>\n

[<\/span>JsonProperty(<\/span>“breweryId”<\/span>)<\/span>]<\/span>
\n[<\/span>CouchbaseViewKey(<\/span>“by_brewery”<\/span>, “breweryId”<\/span>)<\/span>]<\/span>
\npublic<\/span> string<\/span> Brewery {<\/span> get;<\/span> set;<\/span> }<\/span>
\n}<\/span><\/p>\n<\/div>\n<\/div>\n

The CouchbaseDesignDoc<\/em> attribute is set on a model class.\u00a0 It uses a plain-old-CLR-object (POCO) to define a design document.\u00a0 If you omit the name argument, a design document with the same name (lowercased) as the class will be created.\u00a0 If you omit the type argument, views will check that documents have a type property with the value of the name (lowercased) of the class.<\/p>\n

The CouchbaseViewKey<\/em> attribute is set on properties in a POCO class that should be indexed.\u00a0 For example, the Name property in the Beer<\/em> class above has a CouchbaseViewKey<\/em> attribute on it with the arguments “by_name” and “name.”\u00a0 The view that will result from these values is as follows:<\/p>\n

\n
function<\/span>(<\/span>doc,<\/span> meta)<\/span> {<\/span>
\nif<\/span> (<\/span>doc.type<\/span> ==<\/span> “beer”<\/span> &&<\/span> doc.name<\/span>)<\/span> {<\/span>
\nemit(<\/span>doc.name<\/span>,<\/span> null<\/span>)<\/span>;<\/span>
\n}<\/span>
\n}<\/span><\/div>\n<\/div>\n

The “by_name” argument is the name of this view and the “name” argument defines what property is checked for existence and emitted.<\/p>\n

It’s also possible to include composite keys by decorating multiple properties with CouchbaseViewKey<\/em> attributes containing the same value for the viewName parameter.\u00a0 Composite keys are demonstrated with “by_abv_and_name” on the ABV and Name properties.\u00a0 Notice also that there is an optional order parameter that allows you to set the order in which properties are emitted.<\/p>\n

\n
function(<\/span>doc, meta)<\/span> {<\/span>
\nif<\/span> (<\/span>doc.<\/span>type<\/span> ==<\/span> “beer”<\/span> &&<\/span> doc.<\/span>abv<\/span> &&<\/span> doc.<\/span>name<\/span>)<\/span> {<\/span>
\nemit(<\/span>[<\/span>doc.<\/span>abv<\/span>, doc.<\/span>name<\/span>]<\/span>, null<\/span>)<\/span>;<\/span>
\n}<\/span>
\n}<\/span><\/div>\n<\/div>\n

Once you’ve decorated your class with the appropriate attributes, you can use the CouchbaseModelViewsGenerator<\/em> project to run the models through the view generator.\u00a0 This is a simple command line project that requires an app.config with a section listing all assemblies containing models that will be used to create views.<\/p>\n

\n
\n

<sectionGroup<\/span> name<\/span>=“modelViews”<\/span>><\/span><\/span>
\n<section<\/span> name<\/span>=“assemblies”<\/span> type<\/span>=“System.Configuration.DictionarySectionHandler”<\/span>\/><\/span><\/span>
\n><\/span><\/span><\/p>\n

<modelViews><\/span><\/span><\/span>
\n<assemblies><\/span><\/span><\/span>
\n<add<\/span> key<\/span>=“DemoModels”<\/span> value<\/span>=“CouchbaseModelViews.DemoModels”<\/span> \/><\/span><\/span>
\n><\/span><\/span>
\n><\/span><\/span><\/p>\n<\/div>\n<\/div>\n

Additionally, you will need to configure the CouchbaseCluster<\/em>.\u00a0 CouchbaseCluster<\/em> instances are creating using the same configuration (code or app.config) as the existing CouchbaseClient<\/em>.\u00a0 However, there are now an additional two properties you can set to provide the administrator credentials.<\/p>\n

\n
<couchbase><\/span><\/span><\/span>
\n<servers<\/span> bucket<\/span>=“default”<\/span> bucketPassword<\/span>=“”<\/span> username<\/span>=“Administrator”<\/span> password<\/span>=“qwerty”<\/span>><\/span><\/span>
\n<add<\/span> uri<\/span>=“https:\/\/localhost:8091\/pools”<\/span> \/><\/span><\/span>
\n><\/span><\/span>
\n><\/span><\/span><\/div>\n<\/div>\n

Once you’ve setup your app.config, make sure you have the listed assemblies in the bin directory where they can be loaded.\u00a0 The easiest way to achieve this discover-ability is of course to reference them.\u00a0 However, if you just want to use a compiled version of the console app, then simply copy them into the bin directory.<\/p>\n

When executed, the framework will create a “beers” design document that looks like the following:<\/p>\n

\n
{<\/span>
\n“views”<\/span>:<\/span> {<\/span>
\n“by_abv_and_name”<\/span>:<\/span> {<\/span>
\n“map”<\/span>:<\/span> “function(doc, meta) { r<\/span>n<\/span>t<\/span> if (doc.type == “<\/span>beer“<\/span> && doc.abv && doc.name) { r<\/span>n<\/span>t<\/span>t<\/span> emit([doc.abv, doc.name], null); r<\/span>n<\/span>t<\/span> } r<\/span>n<\/span> }”<\/span>
\n}<\/span>,<\/span>
\n“by_name”<\/span>:<\/span> {<\/span>
\n“map”<\/span>:<\/span> “function(doc, meta) { r<\/span>n<\/span>t<\/span> if (doc.type == “<\/span>beer“<\/span> && doc.name) { r<\/span>n<\/span>t<\/span>t<\/span> emit(doc.name, null); r<\/span>n<\/span>t<\/span> } r<\/span>n<\/span> }”<\/span>
\n}<\/span>,<\/span>
\n“by_brewery”<\/span>:<\/span> {<\/span>
\n“map”<\/span>:<\/span> “function(doc, meta) { r<\/span>n<\/span>t<\/span> if (doc.type == “<\/span>beer“<\/span> && doc.breweryId) { r<\/span>n<\/span>t<\/span>t<\/span> emit(doc.breweryId, null); r<\/span>n<\/span>t<\/span> } r<\/span>n<\/span> }”<\/span>
\n}<\/span>
\n}<\/span>
\n}<\/span><\/div>\n<\/div>\n

The console contains no actual view creation logic.\u00a0 It just orchestrates calls to the various plumbing components inside the Framework<\/em> project.\u00a0 If you prefer to include the view creation inside of Global.asax or some other app start event, you could simply make these calls yourself.\u00a0 There are four primary components of the framework.<\/p>\n