ThreeSevenths/Remote.Linq

Simply LINQ your remote resources...

Remote.Linq

branch	AppVeyor	Travis CI	Codecov.io	Codacy	CodeFactor	License
main

package	nuget	myget
Remote.Linq
Remote.Linq.Async.Queryable
Remote.Linq.EntityFramework
Remote.Linq.EntityFrameworkCore
Remote.Linq.Newtonsoft.Json
Remote.Linq.protobuf-net
Remote.Linq.Text.Json

Description

Remote.Linq is a small and easy to use - yet very powerful - library to translate LINQ expression trees to strongly typed, serializable expression trees and vice versa. It provides functionality to send arbitrary LINQ queries to a remote service to be applied and executed against any enumerable or queryable data collection.

Building a LINQ interface for custom services is made a breeze by using Remote.Linq.

Features

• Translate LINQ expressions into serializable expression trees (remote LINQ expression) and vice versa.
• Build remote single-type query services (paging, sorting, filtering).
• Build remote complex LINQ query services (arbitrary LINQ query including joins, groupings, aggregations, projections, etc.).

Scope

In contrast to re-linq, this project enables serialization and deserialization of expression trees and applying LINQ expressions to other LINQ providers e.g. linq-to-object, linq-to-entity, etc.

Remote.Linq makes it super easy to implement a service allowing LINQ queries defined on a client to be executed on a remote server.

Write operations (insert/update/delete) have to be implemented by other means if needed. InfoCarrier.Core might be interesting for such scenarios.

Sample

Check-out Remote.Linq.Samples.sln and samples folder for a number of sample use cases.

Client: Implement a repository class to set-up server connection and expose the queryable data sets (IQueryable<>)

public class ClientDataRepository
{
    private readonly Func<Expression, DynamicObject> _dataProvider;

    public RemoteRepository(string uri)
    {
        _dataProvider = expression =>
            {
                // setup service connectivity
                using IQueryService service = CreateServerConnection(uri);
                // send expression to service and get back results
                DynamicObject result = service.ExecuteQuery(expression);
                return result;
            };
    }

    public IRemoteQueryable<Blog> Blogs => RemoteQueryable.Factory.CreateQueryable<Blog>(_dataProvider);
   
    public IRemoteQueryable<Post> Posts => RemoteQueryable.Factory.CreateQueryable<Post>(_dataProvider);
   
    public IRemoteQueryable<User> Users => RemoteQueryable.Factory.CreateQueryable<User>(_dataProvider);
    
    // where IRemoteQueryable<out T> is IQueryable<out T>
}

Use your repository to compose LINQ query and let the data be retrieved from the backend service

var repository = new ClientDataRepository("https://myserver/queryservice");

var myBlogPosts = (
    from blog in repository.Blogs
    from post in blog.Posts
    join owner in repository.Users on blog.OwnerId equals owner.Id
    where owner.login == "hi-its-me"
    select new 
    {
        post.Title,
        post.Date,
        Preview = post.Text.Substring(0, 50)
    }).ToList();

Server: Implement the backend service to handle the client's query expression by applying it to a data source e.g. an ORM

public interface IQueryService : IDisposable
{
    DynamicObject ExecuteQuery(Expression queryExpression);
}

public class QueryService : IQueryService
{
    // any linq provider e.g. entity framework, nhibernate, ...
    private IDataProvider _datastore = new ObjectRelationalMapper();

    // you need to be able to retrieve an IQueryable by type
    private Func<Type, IQueryable> _queryableProvider = type => _datastore.GetQueryableByType(type);

    public DynamicObject ExecuteQuery(Expression queryExpression)
    {
        // `Execute` is an extension method provided by Remote.Linq
        // it applies an expression to a data source and returns the result
        return queryExpression.Execute(queryableProvider: _queryableProvider);
    }

    public void Dispose() => _datastore.Dispose();
}

Async

IAsyncRemoteQueryable<TEntity> asyncQuery = RemoteQueryable.Factory.CreateAsyncQueryable<TEntity>(...);
TEntity[] result = await asyncQuery.ToArrayAsync().ConfigureAwait(false);

// where interface IAsyncRemoteQueryable<out T> is IRemoteQueryable<out T> is IQueryable<out T>

Async Stream MS doc

IAsyncRemoteStreamQueryable<TEntity> asyncStreamQuery = RemoteQueryable.Factory.CreateAsyncStreamQueryable<TEntity>(...);
await foreach (TEntity item in asyncStreamQuery.ConfigureAwait(false))
{
}

// where interface IAsyncRemoteStreamQueryable<out T> is IQueryable<out T>

Remote.Linq.Async.Queryable

Provides interoperability with Interactive Extensions (Ix.NET / System.Linq.Async.Queryable).

Sample

System.Linq.IAsyncQueryable<TEntity> asyncQuery = RemoteQueryable.Factory.CreateAsyncQueryable<TEntity>(...);
await foreach (TEntity item in asyncQuery.ConfigureAwait(false))
{
}

Remote.Linq.EntityFramework / Remote.Linq.EntityFrameworkCore

Remote linq extensions for Entity Framework and Entity Framework Core.

Use this package when using features specific to EF6 and EF Core:

• Apply eager-loading (Include-expressions)

• Make use of DB functions
  e.g. queryable.Where(x => Microsoft.EntityFrameworkCore.EF.Functions.Like(x.Name, "%fruit%"))

Sample

Client: Query blogs including posts and owner

using var repository = new RemoteRepository();
var blogs = repository.Blogs
    .Include(x => x.Posts).ThenInclude(x => x.Owner)
    .ToList();

Server: Execute query on database via EF Core

public DynamicObject ExecuteQuery(Expression queryExpression)
{
    using var dbContext = new DbContext();
    return queryExpression.ExecuteWithEntityFrameworkCore(dbContext);
}

Remote.Linq.Newtonsoft.Json

Provides Json.NET serialization settings for Remote.Linq types.

Sample

public TExpression DeepCopy<TExpression>(TExpression expression)
    where TExpression : Remote.Linq.Expressions.Expression
{
    JsonSerializerSettings serializerSettings = new JsonSerializerSettings().ConfigureRemoteLinq(); 
    string json = JsonConvert.SerializeObject(expression, serializerSettings); 
    TExpression copy = JsonConvert.DeserializeObject<TExpression>(json, serializerSettings); 
    return copy;
}

Remote.Linq.Text.Json

Provides System.Text.Json serialization settings for Remote.Linq types.

Sample

TEntity entity = ...;
JsonSerializerOptions serializerSettings = new JsonSerializerOptions().ConfigureRemoteLinq();
string json = JsonSerializer.Serialize(entity, serializerSettings);
TEntity result = JsonSerializer.Deserialize<TEntity>(json, serializerSettings);

// Microsoft.AspNetCore.Hosting
new WebHostBuilder()
  .ConfigureServices(services => services
    .AddMvcCore()
    .AddJsonOptions(options => options.JsonSerializerOptions.ConfigureRemoteLinq()))