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using ExpressionTreeToString;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using Tango.BL;
namespace Tango.FSE.BL
{
public abstract class EntityRepositoryBase<TEntity, TCachedEntity> : FSEServiceBase where TEntity : ObservableEntity<TEntity> where TCachedEntity : ObservableEntityDTO<TCachedEntity, TEntity>
{
private MemoryCacheDictionary<String, TCachedEntity> _memoryCache;
public EntityRepositoryBase()
{
_memoryCache = MemoryCache.GetOrCreateCache<String, TCachedEntity>(typeof(TEntity).Name);
}
protected Task<List<TEntity>> FindAll(Expression<Func<TEntity, bool>> expression, params DataResolverNode[] nodes)
{
//Validate expression
if (expression.ToString().Contains("Convert("))
{
throw new NotSupportedException($"Type conversion is not supported by LiteDB. '{expression.ToString()}'");
}
return DataResolver<List<TEntity>>.Builder.New()
.ConfigureCascade(nodes)
.WithLogsCallingName(typeof(TEntity).Name.PluralizeMVC())
.InMemoryCache((context) =>
{
return _memoryCache
.ToList(true)
.Where(GetCacheExpression(expression).Compile())
.ToList()
.Select(x => ConvertToEntity(x))
.ToList();
})
.Online((context) =>
{
using (ObservablesContext db = ObservablesContext.CreateDefault())
{
var entities = db.Set<TEntity>().Where(expression).ToList();
List<TCachedEntity> cachedEntities = new List<TCachedEntity>();
try
{
foreach (var entity in entities)
{
var cachedEntity = ConvertToCached(entity);
cachedEntities.Add(cachedEntity);
_memoryCache.Put(entity.Guid, cachedEntity);
}
}
catch (Exception ex)
{
LogManager.Log(ex, $"Error occurred while trying to cache entities of type '{typeof(TEntity).Name}' to memory.");
}
try
{
using (var cache = DiskCache.CreateContext())
{
var collection = cache.Database.GetCollection<TCachedEntity>();
foreach (var cachedEntity in cachedEntities)
{
collection.Upsert(cachedEntity);
}
}
}
catch (Exception ex)
{
LogManager.Log(ex, $"Error occurred while trying to cache entities of type '{typeof(TEntity).Name}' to disk.");
}
return entities;
}
})
.DiskCache((context) =>
{
using (var cache = DiskCache.CreateContext())
{
List<TEntity> entities = new List<TEntity>();
var cachedEntities = cache.Database.GetCollection<TCachedEntity>().Find(GetCacheExpression(expression)).ToList();
foreach (var cachedEntity in cachedEntities)
{
_memoryCache.Put(cachedEntity.Guid, cachedEntity);
entities.Add(ConvertToEntity(cachedEntity));
}
return entities;
}
})
.BuildExecuteAsync();
}
protected Task<TEntity> FindOne(Expression<Func<TEntity, bool>> expression, params DataResolverNode[] nodes)
{
//Validate expression
if (expression.ToString().Contains("Convert("))
{
throw new NotSupportedException($"Type conversion is not supported by LiteDB. '{expression.ToString()}'");
}
return DataResolver<TEntity>.Builder.New()
.ConfigureCascade(nodes)
.WithLogsCallingName(typeof(TEntity).Name.PluralizeMVC())
.InMemoryCache((context) =>
{
return ConvertToEntity(_memoryCache
.ToList(true)
.First(GetCacheExpression(expression).Compile()));
})
.Online((context) =>
{
using (ObservablesContext db = ObservablesContext.CreateDefault())
{
var entity = db.Set<TEntity>().First(expression);
try
{
TCachedEntity cachedEntity = null;
cachedEntity = ConvertToCached(entity);
_memoryCache.Put(entity.Guid, cachedEntity);
try
{
using (var cache = DiskCache.CreateContext())
{
var collection = cache.Database.GetCollection<TCachedEntity>();
collection.Upsert(cachedEntity);
}
}
catch (Exception ex)
{
LogManager.Log(ex, $"Error caching entity '{entity.Guid}' of type '{typeof(TEntity).Name}' to disk.");
}
}
catch (Exception ex)
{
LogManager.Log(ex, $"Error caching entity '{entity.Guid}' of type '{typeof(TEntity).Name}'.");
}
return entity;
}
})
.DiskCache((context) =>
{
using (var cache = DiskCache.CreateContext())
{
var cachedEntity = cache.Database.GetCollection<TCachedEntity>().FindOne(GetCacheExpression(expression));
if (cachedEntity == null)
{
throw new KeyNotFoundException("The entity was not found on the disk cache.");
}
_memoryCache.Put(cachedEntity.Guid, cachedEntity);
return ConvertToEntity(cachedEntity);
}
})
.BuildExecuteAsync();
}
protected virtual Expression<Func<TCachedEntity, bool>> GetCacheExpression(Expression<Func<TEntity, bool>> expression)
{
var param = Expression.Parameter(typeof(TCachedEntity), expression.Parameters[0].Name);
var result = new CustomExpVisitor<TCachedEntity>(param).Visit(expression.Body);
Expression<Func<TCachedEntity, bool>> lambda = Expression.Lambda<Func<TCachedEntity, bool>>(result, new[] { param });
return lambda;
}
protected abstract TCachedEntity ConvertToCached(TEntity entity);
protected abstract TEntity ConvertToEntity(TCachedEntity cachedEntity);
private class CustomExpVisitor<T> : ExpressionVisitor
{
ParameterExpression _param;
public CustomExpVisitor(ParameterExpression param)
{
_param = param;
}
protected override Expression VisitParameter(ParameterExpression node)
{
return _param;
}
protected override Expression VisitMember(MemberExpression node)
{
if (node.Member.MemberType == MemberTypes.Property)
{
MemberExpression memberExpression = null;
var memberName = node.Member.Name;
var otherMember = typeof(T).GetProperty(memberName);
if (otherMember == null)
{
return base.VisitMember(node);
}
memberExpression = Expression.Property(Visit(node.Expression), otherMember);
return memberExpression;
}
else
{
return base.VisitMember(node);
}
}
}
}
}
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