Moviegraph

Moviegraph is a demo and training application for ASP.NET Core and Neo4j.

Setup 1: Install Neo4j

wget http://dist.neo4j.org/neo4j-community-3.4.7-unix.tar.gz
tar xf neo4j-community-3.4.7-unix.tar.gz
cd neo4j-community-3.4.7
bin/neo4j-admin set-initial-password password
bin/neo4j start|console

Setup 2: Install a data set

Browse to
http://localhost:7474/
:play movies
call db.schema
(explore a bit)

Setup 3: Install application skeleton

git clone ...
export ASPNETCORE_ENVIRONMENT=Development
cd MovieGraph.Web && dotnet run

If you want to use a different language, feel free to convert the code.

Setup 4: Open the application

http://127.0.0.1:5000

Code walk 1: Project structure

• Answers/ - all the answers!!
• MovieGraph.sln - the solution file that includes the project MovieGraph.Web
• MovieGraph.Web/ - the project itself
• MovieGraph.Web/Controllers/ - the MVC controllers
• MovieGraph.Web/Views/ - the MVC views (razor)
• MovieGraph.Web/Model/ - the MVC models
• MovieGraph.Web/Helpers/ - couple of extension methods for Neo4j
• MovieGraph.Web/wwwroot/ - the static files (css)

Code walk 2: Neo4j driver

The driver is added as a service - Startup.cs

// Add Neo4j Driver As A Singleton Service
services.AddSingleton<IDriver>(provider => GraphDatabase.Driver("bolt://localhost:7687", AuthTokens.Basic("neo4j", "password")));

Code walk 3: MVC Controllers

MVC controllers accept IDriver in their constructors, ASP.NET MVC passes our already registered singleton instance.

private readonly IDriver driver;

public HomeController(IDriver driver)
{
    this.driver = driver;
}

Code walk 4: Home page

You can have a look at the home page view templates at Views/Home.

[Route("")]
public async Task<IActionResult> Index(string q)
{
    return View("Index", await MatchMovies(q));
}

Code walk 5: MatchMovies function

private async Task<IEnumerable<MovieModel>> MatchMovies(string term)
{
    if (string.IsNullOrEmpty(term))
    {
        return Enumerable.Empty<MovieModel>();
    }

    var session = driver.Session();
    try
    {
        return await session.ReadTransactionAsync(async tx =>
        {
            var cursor =
                await tx.RunAsync(
                    "MATCH (movie:Movie) WHERE toLower(movie.title) " +
                    "CONTAINS toLower($term) RETURN movie",
                    new {term});

            return await cursor.ToListAsync(record => new MovieModel(record));
        });
    }
    finally
    {
        if (session != null)
        {
            await session.CloseAsync();
        }
    }
}

Code walk 6: Movie page

You can have a look at the home page view templates at Views/Movie.

[Route("{id}")]
public async Task<IActionResult> Index(string id)
{
    var movie = await MatchMovie(id);
    if (movie == null)
    {
        return StatusCode(404);
    }

    return View("Index", movie);
}

Code walk 7: MatchMovie function

private async Task<MovieModel> MatchMovie(string title)
{
    var session = driver.Session();
    try
    {
        return await session.ReadTransactionAsync(async tx =>
        {
            var cursor =
                await tx.RunAsync(
                    "MATCH (movie:Movie) WHERE movie.title = $title " +
                    "OPTIONAL MATCH(person) -[:ACTED_IN]->(movie) " +
                    "RETURN movie, collect(person) AS actors",
                    new {title});

            return new MovieModel(await cursor.SingleAsync());
        });
    }
    finally
    {
        if (session != null)
        {
            await session.CloseAsync();
        }
    }
}

Code walk 8: MovieModel model

GetOrDefault functions used are defined as extension methods by the static classes in Helpers folder.

public class MovieModel
{
    public const string MovieKey = "movie";
    public const string TitleKey = "title";
    public const string TaglineKey = "tagline";
    public const string ReleasedKey = "released";
    public const string ActorsKey = "actors";

    public MovieModel(IRecord record)
    {
        var movie = record.GetOrDefault(MovieKey, (INode) null);
        if (movie != null)
        {
            Title = movie.GetOrDefault<string>(TitleKey, null);
            Tagline = movie.GetOrDefault<string>(TaglineKey, null);
            Released = movie.GetOrDefault<int?>(ReleasedKey, null);
        }

        var actors = record.GetOrDefault(ActorsKey, (List<object>) null);
        if (actors != null)
        {
            Actors = actors.Select(actor => new PersonModel((INode) actor)).OrderBy(p => p.Name);
        }
    }

    public string Title { get; }

    public string Tagline { get; }

    public int? Released { get; }

    public IEnumerable<PersonModel> Actors { get; }
}

Code walk 9: PersonModel model

GetOrDefault functions used are defined as extension methods by the static classes in Helpers folder.

public class PersonModel
{
    public const string NameKey = "name";

    public PersonModel(INode node)
    {
        if (node == null)
        {
            throw new ArgumentNullException(nameof(node));
        }

        Name = node.GetOrDefault<string>(NameKey, null);
    }

    public string Name { get; }
}

Exercise 1: Add Person pages

• Add links behind the movie cast list (movies are rendered by templates in Views/Movie)
• Add a new Person controller (in Controllers)
• Modify PersonModel to include year of birth and all films played in (in Model)
• Add a new view template for Person (save new view file(s) in Views/Person)

cd Answers/1/MovieGraph.Web && dotnet run

Exercise 2: Add star ratings

• Add clickable star rating to each movie (movies are rendered by templates in Views/Movie)
• Add handler for POST requests to /movie/<title> (in Controllers/MovieController)
• Modify MovieModel to include stored star rating (in Model)

cd Answers/2/MovieGraph.Web && dotnet run

Exercise 3: Improve search page

• Add stars to search results (search results are rendered by templates in Views/Home)
• Add order by box (search box is rendered in Views/Shared/_Layout.cshtml)

cd Answers/3/MovieGraph.Web && dotnet run