I am trying to find records in a Postgresql table with a column of type Date using a simple equality. I am using DateTime properties (not noda)
I am sure that I am missing something very basic because I am not succeeding after trying many different ways.
The following code does not return any result even though the date is equal to Dates in the database:
var m = new Model {
dateprop = default(DateTime)
}
var result = await context.Model
.Where(a => a.dateprop == m.dateprop)
.ToListAsync()
In the database, there are plenty of records with such date, 0001-01-01, in the column.
Besides, I have tried:
.Where(a => a.dateprop == m.dateprop.Date)
.Where(a => a.dateprop.Date == m.dateprop.Date)
.Where(a => a.dateprop.Date == m.dateprop)
.Where(a => a.dateprop.Equals( m.dateprop)) and all the varieties above
Then, if I get the query that EF produces for .Where(a => a.dateprop.Date == m.dateprop.Date) and run it from a SQL client, it works and returns all the records.
What is the correct way to define the Date equality condition in the where clause?
Edit
I have edited the question since it was misleading, my apologies. Originally, the code showed as:
var m = new Model {
dateprop = DateTime.Parse("1970-01-01")
}
var result = await context.Model
.Where(a => a.dateprop == m.dateprop)
.ToListAsync()
The following runnable code sample works. I'd double-check my database to see exactly what's in there and whether it corresponds to default(DateTime), and if you're still convinced there's an issue, try tweaking the code below to make it appear.
class Program
{
static async Task Main(string[] args)
{
await using var ctx = new BlogContext();
await ctx.Database.EnsureDeletedAsync();
await ctx.Database.EnsureCreatedAsync();
var m = new Model
{
DateProperty = default
};
var result = await ctx.Model
.Where(a => a.DateProperty == m.DateProperty)
.ToListAsync();
Console.WriteLine($"Count: {result.Count}");
}
}
public class BlogContext : DbContext
{
public DbSet<Model> Model { get; set; }
static ILoggerFactory ContextLoggerFactory
=> LoggerFactory.Create(b => b.AddConsole().AddFilter("", LogLevel.Information));
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
=> optionsBuilder
.UseNpgsql(#"Host=localhost;Username=test;Password=test")
.EnableSensitiveDataLogging()
.UseLoggerFactory(ContextLoggerFactory);
protected override void OnModelCreating(ModelBuilder modelBuilder)
=> modelBuilder.Entity<Model>().HasData(
new Model { Id = -1, DateProperty = default });
}
public class Model
{
public int Id { get; set; }
public DateTime DateProperty { get; set; }
}
I'm using Specification pattern in EF Code First. When I do order by operation, VS throw a new exception
The specification pattern is copy from eShopOnWeb
I just change a little bit, here is my change code:
public class Specification<T> : ISpecification<T>
{
public Expression<Func<T, object>> OrderBy { get; private set; }
public Specification(Expression<Func<T, bool>> criteria)
{
Criteria = criteria;
}
public Specification<T> OrderByFunc(Expression<Func<T, object>> orderByExpression)
{
OrderBy = orderByExpression;
return this;
}
}
Here is my invoke code, it's very pretty simple:
static void TestSpec()
{
var spec = new Specification<ExcelData>(x => x.RowIndex == 5)
.OrderByFunc(x => x.ColumnIndex);
using (var dbContext = new TechDbContext())
{
var top10Data = dbContext.ExcelData.Take(10).ToList();
var listExcel = dbContext.ApplySpecification(spec).ToList();
Console.WriteLine();
}
}
If I comment OrderByFunc, then everything is fine to me. no error throw from vs.
I had try many times search the error message in google, but none of answer is my case.
So I have to ask a question in here.
When I debug OrderBy property in SpecificationEvaluator.cs, I found there is a Convert method.
So I know the error is about cast error, but how do I fix this cast type error?
Please help me!
The solution is to create new lambda expression with cast (Convert) removed, and then use it to call the Queryable class OrderBy / OrderByDescending method either dynamically (using DLR dispatch or reflection) or by emitting Expression.Call to it.
For the first part, add the following helper method to the SpecificationEvaluator class:
static LambdaExpression RemoveConvert(LambdaExpression source)
{
var body = source.Body;
while (body.NodeType == ExpressionType.Convert)
body = ((UnaryExpression)body).Operand;
return Expression.Lambda(body, source.Parameters);
}
Then replace the code
query = query.OrderBy(specification.OrderBy);
with either
query = Queryable.OrderBy((dynamic)query, (dynamic)RemoveConvert(specification.OrderBy));
or
var keySelector = RemoveConvert(specification.OrderBy);
query = query.Provider.CreateQuery<T>(Expression.Call(
typeof(Queryable), nameof(Queryable.OrderBy),
new[] { typeof(T), keySelector.ReturnType },
query.Expression, keySelector));
Do similar for the specification.OrderByDescending.
The examples I've seen for using moq for a repository only show how to mock things being returned. I have a somewhat strange requirement: when a query is executed, if a condition exists, a certain item should be added to the repository. I am wondering how to test this without querying the database. I know how to mock the condition existing, but then how do you setup the mock so that you can test that the certain item is added?
Try to use fake in memory repository instead of moq, for example universal generic repository for all entities:
public interface IInMemoryRepository<T> where T : class
{
IQueryable<T> GetAll();
void Create(T item);
void Update(T item);
T GetItem(Expression<Func<T, bool>> expression);
void Delete(T item);
}
public class InMemoryRepository<T> : IInMemoryRepository<T> where T : class
{
private int _incrementer = 0;
public Dictionary<int, T> List = new Dictionary<int, T>();
public IQueryable<T> GetAll()
{
return List.Select(x => x.Value).AsQueryable();
}
public void Create(T item)
{
_incrementer++;
item.GetType().GetProperties().First(p => p.Name == "Id").SetValue(item, _incrementer, null);
List.Add(_incrementer, item);
}
public void Update(T item)
{
var key = (int)item.GetType().GetProperties().First(p => p.Name == "Id").GetValue(item, null);
List[key] = item;
}
public T GetItem(Expression<Func<T, bool>> expression)
{
return List.Select(x => x.Value).SingleOrDefault(expression.Compile());
}
public void Delete(T item)
{
var key = (int)item.GetType().GetProperties().First(p => p.Name == "Id").GetValue(item, null);
List.Remove(key);
}
}
You would not mock the repository; you would have an alternate repository that would use an in-memory store instead of the database, then use IoC to select the correct repository implementation for tests/code.
This blog article might be of use, although my design has changed somewhat since I wrote the post and I really need to update it. I used teh generic repository pattern in a way that enables the DbContext to be mocked. This allows the data access layer to be tested 'right up to the edges'.
Times have changed -- since the release of Entity Framework 6 it has become much easier to mock database context and datasets. This article outlines the particulars.
Testing non-query scenarios
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Moq;
using System.Data.Entity;
namespace TestingDemo
{
[TestClass]
public class NonQueryTests
{
[TestMethod]
public void CreateBlog_saves_a_blog_via_context()
{
var mockSet = new Mock<DbSet<Blog>>();
var mockContext = new Mock<BloggingContext>();
mockContext.Setup(m => m.Blogs).Returns(mockSet.Object);
var service = new BlogService(mockContext.Object);
service.AddBlog("ADO.NET Blog", "http://blogs.msdn.com/adonet");
mockSet.Verify(m => m.Add(It.IsAny<Blog>()), Times.Once());
mockContext.Verify(m => m.SaveChanges(), Times.Once());
}
}
}
Testing query scenarios
Query testing is pretty sweet now, because you can build up test data sets in code and then execute your tests against them:
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Moq;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
namespace TestingDemo
{
[TestClass]
public class QueryTests
{
[TestMethod]
public void GetAllBlogs_orders_by_name()
{
var data = new List<Blog>
{
new Blog { Name = "BBB" },
new Blog { Name = "ZZZ" },
new Blog { Name = "AAA" },
}.AsQueryable();
var mockSet = new Mock<DbSet<Blog>>();
mockSet.As<IQueryable<Blog>>().Setup(m => m.Provider).Returns(data.Provider);
mockSet.As<IQueryable<Blog>>().Setup(m => m.Expression).Returns(data.Expression);
mockSet.As<IQueryable<Blog>>().Setup(m => m.ElementType).Returns(data.ElementType);
mockSet.As<IQueryable<Blog>>().Setup(m => m.GetEnumerator()).Returns(0 => data.GetEnumerator());
var mockContext = new Mock<BloggingContext>();
mockContext.Setup(c => c.Blogs).Returns(mockSet.Object);
var service = new BlogService(mockContext.Object);
var blogs = service.GetAllBlogs();
Assert.AreEqual(3, blogs.Count);
Assert.AreEqual("AAA", blogs[0].Name);
Assert.AreEqual("BBB", blogs[1].Name);
Assert.AreEqual("ZZZ", blogs[2].Name);
}
}
}
You can do this by mocking the DbSet.Add() method, like so:
[Fact]
public void CreateBlog_saves_a_blog_via_context()
{
var data = new List<Blog>
{
new Blog { Name = "BBB" },
new Blog { Name = "ZZZ" },
new Blog { Name = "AAA" },
};
var mockSet = new Mock<DbSet<Blog>>();
mockSet.Setup(blogs => blogs.Add(It.IsAny<Blog>)).Returns<Blog>(blog =>
{
data.Add(blog);
return blog;
});
var mockContext = new Mock<BloggingContext>();
mockContext.Setup(m => m.Blogs).Returns(mockSet.Object);
var service = new BlogService(mockContext.Object);
var blog = service.AddBlog("_ADO.NET Blog", "http://blogs.msdn.com/adonet");
var blogs = service.GetAllBlogs();
mockSet.Verify(m => m.Add(It.IsAny<Blog>()), Times.Once());
mockContext.Verify(m => m.SaveChanges(), Times.Once());
Assert.NotNull(blog)
Assert.Equal(4, blogs.Count);
Assert.Equal("AAA", blogs(1).Name);
Assert.Equal("BBB", blogs(2).Name);
Assert.Equal("ZZZ", blogs(3).Name);
}
This is adapted from the documentation found here.
How do I view the SQL generated by entity framework ?
(In my particular case I'm using the mysql provider - if it matters)
For those using Entity Framework 6 and up, if you want to view the output SQL in Visual Studio (like I did) you have to use the new logging/interception functionality.
Adding the following line will spit out the generated SQL (along with additional execution-related details) in the Visual Studio output panel:
using (MyDatabaseEntities context = new MyDatabaseEntities())
{
context.Database.Log = s => System.Diagnostics.Debug.WriteLine(s);
// query the database using EF here.
}
More information about logging in EF6 in this nifty blog series: http://blog.oneunicorn.com/2013/05/08/ef6-sql-logging-part-1-simple-logging/
Note: Make sure you are running your project in DEBUG mode.
You can do the following:
IQueryable query = from x in appEntities
where x.id == 32
select x;
var sql = ((System.Data.Objects.ObjectQuery)query).ToTraceString();
or in EF6:
var sql = ((System.Data.Entity.Core.Objects.ObjectQuery)query)
.ToTraceString();
or in EF6.3+:
var sql = ((dynamic)flooringStoresProducts).Sql;
That will give you the SQL that was generated.
Starting with EF6.1 you can use Interceptors to register a database logger.
See chapters "Interceptors" and "Logging Database Operations" to a File here
<configuration>
<entityFramework>
<interceptors>
<interceptor type="System.Data.Entity.Infrastructure.Interception.DatabaseLogger, EntityFramework">
<parameters>
<parameter value="C:\Temp\LogOutput.txt"/>
<parameter value="true" type="System.Boolean"/>
</parameters>
</interceptor>
</interceptors>
</entityFramework>
</configuration>
If you are using a DbContext, you can do the following to get the SQL:
var result = from i in myContext.appEntities
select new Model
{
field = i.stuff,
};
var sql = result.ToString();
EF Core 5.0+
This loooong-awaited feature is available in EF Core 5.0! This is from the weekly status updates:
var query = context.Set<Customer>().Where(c => c.City == city);
Console.WriteLine(query.ToQueryString())
results in this output when using the SQL Server database provider:
DECLARE p0 nvarchar(4000) = N'London';
SELECT [c].[CustomerID], [c].[Address], [c].[City], [c].[CompanyName],
[c].[ContactName], [c].[ContactTitle], [c].[Country], [c].[Fax], [c].[Phone],
[c].[PostalCode], [c].[Region]
FROM [Customers] AS [c]
WHERE [c].[City] = #__city_0
Notice that declarations for parameters of the correct type are also
included in the output. This allows copy/pasting to SQL Server
Management Studio, or similar tools, such that the query can be
executed for debugging/analysis.
woohoo!!!
(Note: You will need using Microsoft.EntityFrameworkCore;)
Applicable for EF 6.0 and above:
For those of you wanting to know more about the logging functionality and adding to the some of the answers already given.
Any command sent from the EF to the database can now be logged. To view the generated queries from EF 6.x, use the DBContext.Database.Log property
What Gets Logged
- SQL for all different kinds of commands. For example:
- Queries, including normal LINQ queries, eSQL queries, and raw queries from methods such as SqlQuery.
- Inserts, updates, and deletes generated as part of SaveChanges
- Relationship loading queries such as those generated by lazy loading
- Parameters
- Whether or not the command is being executed asynchronously
- A timestamp indicating when the command started executing
- Whether or not the command completed successfully, failed by throwing an exception, or, for async, was canceled
- Some indication of the result value
- The approximate amount of time it took to execute the command. Note that this is the time from sending the command to getting the result object back. It does not include time to read the results.
Example:
using (var context = new BlogContext())
{
context.Database.Log = Console.Write;
var blog = context.Blogs.First(b => b.Title == "One Unicorn");
blog.Posts.First().Title = "Green Eggs and Ham";
blog.Posts.Add(new Post { Title = "I do not like them!" });
context.SaveChangesAsync().Wait();
}
Output:
SELECT TOP (1)
[Extent1].[Id] AS [Id],
[Extent1].[Title] AS [Title]
FROM [dbo].[Blogs] AS [Extent1]
WHERE (N'One Unicorn' = [Extent1].[Title]) AND ([Extent1].[Title] IS NOT NULL)
-- Executing at 10/8/2013 10:55:41 AM -07:00
-- Completed in 4 ms with result: SqlDataReader
SELECT
[Extent1].[Id] AS [Id],
[Extent1].[Title] AS [Title],
[Extent1].[BlogId] AS [BlogId]
FROM [dbo].[Posts] AS [Extent1]
WHERE [Extent1].[BlogId] = #EntityKeyValue1
-- EntityKeyValue1: '1' (Type = Int32)
-- Executing at 10/8/2013 10:55:41 AM -07:00
-- Completed in 2 ms with result: SqlDataReader
UPDATE [dbo].[Posts]
SET [Title] = #0
WHERE ([Id] = #1)
-- #0: 'Green Eggs and Ham' (Type = String, Size = -1)
-- #1: '1' (Type = Int32)
-- Executing asynchronously at 10/8/2013 10:55:41 AM -07:00
-- Completed in 12 ms with result: 1
INSERT [dbo].[Posts]([Title], [BlogId])
VALUES (#0, #1)
SELECT [Id]
FROM [dbo].[Posts]
WHERE ##ROWCOUNT > 0 AND [Id] = scope_identity()
-- #0: 'I do not like them!' (Type = String, Size = -1)
-- #1: '1' (Type = Int32)
-- Executing asynchronously at 10/8/2013 10:55:41 AM -07:00
-- Completed in 2 ms with result: SqlDataReader
To log to an external file:
using (var context = new BlogContext())
{
using (var sqlLogFile = new StreamWriter("C:\\temp\\LogFile.txt"))
{
context.Database.Log = sqlLogFile.Write;
var blog = context.Blogs.First(b => b.Title == "One Unicorn");
blog.Posts.First().Title = "Green Eggs and Ham";
context.SaveChanges();
}
}
More info here: Logging and Intercepting Database Operations
You can do the following in EF 4.1:
var result = from x in appEntities
where x.id = 32
select x;
System.Diagnostics.Trace.WriteLine(result .ToString());
That will give you the SQL that was generated.
My answer addresses EF core. I reference this github issue, and the docs on configuring DbContext:
Simple
Override the OnConfiguring method of your DbContext class (YourCustomDbContext) as shown here to use a ConsoleLoggerProvider; your queries should log to the console:
public class YourCustomDbContext : DbContext
{
#region DefineLoggerFactory
public static readonly LoggerFactory MyLoggerFactory
= new LoggerFactory(new[] {new ConsoleLoggerProvider((_, __) => true, true)});
#endregion
#region RegisterLoggerFactory
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
=> optionsBuilder
.UseLoggerFactory(MyLoggerFactory); // Warning: Do not create a new ILoggerFactory instance each time
#endregion
}
Complex
This Complex case avoids overriding the DbContext OnConfiguring method. , which is discouraged in the docs: "This approach does not lend itself to testing, unless the tests target the full database."
This Complex case uses:
The IServiceCollection in Startup class ConfigureServices method
(instead of overriding the OnConfiguring method; the benefit is a looser coupling between the DbContext and the ILoggerProvider you want to use)
An implementation of ILoggerProvider (instead of using the ConsoleLoggerProvider implementation shown above; benefit is our implementation shows how we would log to File (I don't see a File Logging Provider shipped with EF Core))
Like this:
public class Startup
public void ConfigureServices(IServiceCollection services)
{
...
var lf = new LoggerFactory();
lf.AddProvider(new MyLoggerProvider());
services.AddDbContext<YOUR_DB_CONTEXT>(optionsBuilder => optionsBuilder
.UseSqlServer(connection_string)
//Using the LoggerFactory
.UseLoggerFactory(lf));
...
}
}
Here's the implementation of a MyLoggerProvider (and its MyLogger which appends its logs to a File you can configure; your EF Core queries will appear in the file.)
public class MyLoggerProvider : ILoggerProvider
{
public ILogger CreateLogger(string categoryName)
{
return new MyLogger();
}
public void Dispose()
{ }
private class MyLogger : ILogger
{
public bool IsEnabled(LogLevel logLevel)
{
return true;
}
public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
{
File.AppendAllText(#"C:\temp\log.txt", formatter(state, exception));
Console.WriteLine(formatter(state, exception));
}
public IDisposable BeginScope<TState>(TState state)
{
return null;
}
}
}
To have the query always handy, without changing code
add this to your DbContext and check it on the output window in visual studio.
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
Database.Log = (query)=> Debug.Write(query);
}
Similar to #Matt Nibecker answer, but with this you do not have to add it in your current code, every time you need the query.
There are two ways:
To view the SQL that will be generated, simply call ToTraceString(). You can add it into your watch window and set a breakpoint to see what the query would be at any given point for any LINQ query.
You can attach a tracer to your SQL server of choice, which will show you the final query in all its gory detail. In the case of MySQL, the easiest way to trace the queries is simply to tail the query log with tail -f. You can learn more about MySQL's logging facilities in the official documentation. For SQL Server, the easiest way is to use the included SQL Server profiler.
I am doing integration test, and needed this to debug the generated SQL statement in Entity Framework Core 2.1, so I use DebugLoggerProvider or ConsoleLoggerProvider like so:
[Fact]
public async Task MyAwesomeTest
{
//setup log to debug sql queries
var loggerFactory = new LoggerFactory();
loggerFactory.AddProvider(new DebugLoggerProvider());
loggerFactory.AddProvider(new ConsoleLoggerProvider(new ConsoleLoggerSettings()));
var builder = new DbContextOptionsBuilder<DbContext>();
builder
.UseSqlServer("my connection string") //"Server=.;Initial Catalog=TestDb;Integrated Security=True"
.UseLoggerFactory(loggerFactory);
var dbContext = new DbContext(builder.Options);
........
Here is a sample output from Visual Studio console:
SQL Management Studio => Tools => SQL Server profiler
File => New Trace...
Use the Template => Blank
Event selection => T-SQL
Lefthandside check for: SP.StmtComplete
Column filters can be used to select a specific ApplicationName or DatabaseName
Start that profile running then trigger the query.
Click here for Source information
Use Logging with Entity Framework Core 3.x
Entity Framework Core emits SQL via the logging system. There are only a couple of small tricks. You must specify an ILoggerFactory and you must specify a filter. Here is an example from this article
Create the factory:
var loggerFactory = LoggerFactory.Create(builder =>
{
builder
.AddConsole((options) => { })
.AddFilter((category, level) =>
category == DbLoggerCategory.Database.Command.Name
&& level == LogLevel.Information);
});
Tell the DbContext to use the factory in the OnConfiguring method:
optionsBuilder.UseLoggerFactory(_loggerFactory);
From here, you can get a lot more sophisticated and hook into the Log method to extract details about the executed SQL. See the article for a full discussion.
public class EntityFrameworkSqlLogger : ILogger
{
#region Fields
Action<EntityFrameworkSqlLogMessage> _logMessage;
#endregion
#region Constructor
public EntityFrameworkSqlLogger(Action<EntityFrameworkSqlLogMessage> logMessage)
{
_logMessage = logMessage;
}
#endregion
#region Implementation
public IDisposable BeginScope<TState>(TState state)
{
return default;
}
public bool IsEnabled(LogLevel logLevel)
{
return true;
}
public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
{
if (eventId.Id != 20101)
{
//Filter messages that aren't relevant.
//There may be other types of messages that are relevant for other database platforms...
return;
}
if (state is IReadOnlyList<KeyValuePair<string, object>> keyValuePairList)
{
var entityFrameworkSqlLogMessage = new EntityFrameworkSqlLogMessage
(
eventId,
(string)keyValuePairList.FirstOrDefault(k => k.Key == "commandText").Value,
(string)keyValuePairList.FirstOrDefault(k => k.Key == "parameters").Value,
(CommandType)keyValuePairList.FirstOrDefault(k => k.Key == "commandType").Value,
(int)keyValuePairList.FirstOrDefault(k => k.Key == "commandTimeout").Value,
(string)keyValuePairList.FirstOrDefault(k => k.Key == "elapsed").Value
);
_logMessage(entityFrameworkSqlLogMessage);
}
}
#endregion
}
IQueryable query = from x in appEntities
where x.id = 32
select x;
var queryString = query.ToString();
Will return the sql query. Working using datacontext of EntityFramework 6
Necromancing.
This page is the first search result when searching for a solution for any .NET Framework, so here as a public service, how it's done in EntityFrameworkCore (for .NET Core 1 & 2):
var someQuery = (
from projects in _context.projects
join issues in _context.issues on projects.Id equals issues.ProjectId into tmpMapp
from issues in tmpMapp.DefaultIfEmpty()
select issues
) //.ToList()
;
// string sql = someQuery.ToString();
// string sql = Microsoft.EntityFrameworkCore.IQueryableExtensions.ToSql(someQuery);
// string sql = Microsoft.EntityFrameworkCore.IQueryableExtensions1.ToSql(someQuery);
// using Microsoft.EntityFrameworkCore;
string sql = someQuery.ToSql();
System.Console.WriteLine(sql);
And then these extension methods (IQueryableExtensions1 for .NET Core 1.0, IQueryableExtensions for .NET Core 2.0) :
using System;
using System.Linq;
using System.Reflection;
using Microsoft.EntityFrameworkCore.Internal;
using Microsoft.EntityFrameworkCore.Query;
using Microsoft.EntityFrameworkCore.Query.Internal;
using Microsoft.EntityFrameworkCore.Storage;
using Remotion.Linq.Parsing.Structure;
namespace Microsoft.EntityFrameworkCore
{
// https://stackoverflow.com/questions/1412863/how-do-i-view-the-sql-generated-by-the-entity-framework
// http://rion.io/2016/10/19/accessing-entity-framework-core-queries-behind-the-scenes-in-asp-net-core/
public static class IQueryableExtensions
{
private static readonly TypeInfo QueryCompilerTypeInfo = typeof(QueryCompiler).GetTypeInfo();
private static readonly FieldInfo QueryCompilerField = typeof(EntityQueryProvider).GetTypeInfo().DeclaredFields
.First(x => x.Name == "_queryCompiler");
private static readonly PropertyInfo NodeTypeProviderField =
QueryCompilerTypeInfo.DeclaredProperties.Single(x => x.Name == "NodeTypeProvider");
private static readonly MethodInfo CreateQueryParserMethod =
QueryCompilerTypeInfo.DeclaredMethods.First(x => x.Name == "CreateQueryParser");
private static readonly FieldInfo DataBaseField =
QueryCompilerTypeInfo.DeclaredFields.Single(x => x.Name == "_database");
private static readonly PropertyInfo DatabaseDependenciesField =
typeof(Database).GetTypeInfo().DeclaredProperties.Single(x => x.Name == "Dependencies");
public static string ToSql<TEntity>(this IQueryable<TEntity> query) where TEntity : class
{
if (!(query is EntityQueryable<TEntity>) && !(query is InternalDbSet<TEntity>))
{
throw new ArgumentException("Invalid query");
}
var queryCompiler = (QueryCompiler) QueryCompilerField.GetValue(query.Provider);
var nodeTypeProvider = (INodeTypeProvider) NodeTypeProviderField.GetValue(queryCompiler);
var parser = (IQueryParser) CreateQueryParserMethod.Invoke(queryCompiler, new object[] {nodeTypeProvider});
var queryModel = parser.GetParsedQuery(query.Expression);
var database = DataBaseField.GetValue(queryCompiler);
var databaseDependencies = (DatabaseDependencies) DatabaseDependenciesField.GetValue(database);
var queryCompilationContext = databaseDependencies.QueryCompilationContextFactory.Create(false);
var modelVisitor = (RelationalQueryModelVisitor) queryCompilationContext.CreateQueryModelVisitor();
modelVisitor.CreateQueryExecutor<TEntity>(queryModel);
var sql = modelVisitor.Queries.First().ToString();
return sql;
}
}
public class IQueryableExtensions1
{
private static readonly TypeInfo QueryCompilerTypeInfo = typeof(QueryCompiler).GetTypeInfo();
private static readonly FieldInfo QueryCompilerField = typeof(EntityQueryProvider).GetTypeInfo()
.DeclaredFields
.First(x => x.Name == "_queryCompiler");
private static readonly PropertyInfo NodeTypeProviderField =
QueryCompilerTypeInfo.DeclaredProperties.Single(x => x.Name == "NodeTypeProvider");
private static readonly MethodInfo CreateQueryParserMethod =
QueryCompilerTypeInfo.DeclaredMethods.First(x => x.Name == "CreateQueryParser");
private static readonly FieldInfo DataBaseField =
QueryCompilerTypeInfo.DeclaredFields.Single(x => x.Name == "_database");
private static readonly FieldInfo QueryCompilationContextFactoryField = typeof(Database).GetTypeInfo()
.DeclaredFields.Single(x => x.Name == "_queryCompilationContextFactory");
public static string ToSql<TEntity>(IQueryable<TEntity> query) where TEntity : class
{
if (!(query is EntityQueryable<TEntity>) && !(query is InternalDbSet<TEntity>))
{
throw new ArgumentException("Invalid query");
}
var queryCompiler = (IQueryCompiler) QueryCompilerField.GetValue(query.Provider);
var nodeTypeProvider = (INodeTypeProvider) NodeTypeProviderField.GetValue(queryCompiler);
var parser =
(IQueryParser) CreateQueryParserMethod.Invoke(queryCompiler, new object[] {nodeTypeProvider});
var queryModel = parser.GetParsedQuery(query.Expression);
var database = DataBaseField.GetValue(queryCompiler);
var queryCompilationContextFactory =
(IQueryCompilationContextFactory) QueryCompilationContextFactoryField.GetValue(database);
var queryCompilationContext = queryCompilationContextFactory.Create(false);
var modelVisitor = (RelationalQueryModelVisitor) queryCompilationContext.CreateQueryModelVisitor();
modelVisitor.CreateQueryExecutor<TEntity>(queryModel);
var sql = modelVisitor.Queries.First().ToString();
return sql;
}
}
}
Well, I am using Express profiler for that purpose at the moment, the drawback is that it only works for MS SQL Server. You can find this tool here: https://expressprofiler.codeplex.com/
While there are good answers here, none solved my problem completely (I wished to get the entire SQL statement, including Parameters, from the DbContext from any IQueryable. The following code does just that. It is a combination of code snippets from Google. I have only tested it with EF6+.
Just an aside, this task took me way longer than I thought it would. Abstraction in Entity Framework is a bit much, IMHO.
First the using. You will need an explicit reference to 'System.Data.Entity.dll'.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlClient;
using System.Data.Common;
using System.Data.Entity.Core.Objects;
using System.Data.Entity;
using System.Data;
using System.Data.Entity.Infrastructure;
using System.Reflection;
The following class converts an IQueryable into a DataTable. Modify as your need may be:
public class EntityFrameworkCommand
{
DbContext Context;
string SQL;
ObjectParameter[] Parameters;
public EntityFrameworkCommand Initialize<T>(DbContext context, IQueryable<T> query)
{
Context = context;
var dbQuery = query as DbQuery<T>;
// get the IInternalQuery internal variable from the DbQuery object
var iqProp = dbQuery.GetType().GetProperty("InternalQuery", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
var iq = iqProp.GetValue(dbQuery, null);
// get the ObjectQuery internal variable from the IInternalQuery object
var oqProp = iq.GetType().GetProperty("ObjectQuery", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
var objectQuery = oqProp.GetValue(iq, null) as ObjectQuery<T>;
SQL = objectQuery.ToTraceString();
Parameters = objectQuery.Parameters.ToArray();
return this;
}
public DataTable GetData()
{
DataTable dt = new DataTable();
var connection = Context.Database.Connection;
var state = connection.State;
if (!(state == ConnectionState.Open))
connection.Open();
using (var cmd = connection.CreateCommand())
{
cmd.CommandText = SQL;
foreach (var p in Parameters)
{
var param = cmd.CreateParameter();
param.Name = "#" + p.Name;
param.Value = p.Value;
cmd.Parameters.Add(param);
}
using (var da = DbProviderFactories.GetFactory(connection).CreateDataAdapter())
{
da.SelectCommand = cmd;
da.Fill(dt);
}
}
if (!(state == ConnectionState.Open))
connection.Close();
return dt;
}
}
To use, simply call it as below:
var context = new MyContext();
var data = ....//Query, return type can be anonymous
.AsQueryable();
var dt = new EntityFrameworkCommand()
.Initialize(context, data)
.GetData();
For me, using EF6 and Visual Studio 2015 I entered query in the immediate window and it gave me the generated SQL Statement
In my case for EF 6+, instead of using this in the Immediate Window to find the query string:
var sql = ((System.Data.Entity.Core.Objects.ObjectQuery)query).ToTraceString();
I ended up having to use this to get the generated SQL command:
var sql = ((System.Data.Entity.Infrastructure.DbQuery<<>f__AnonymousType3<string,string,string,short,string>>)query).ToString();
Of course your anonymous type signature might be different.
HTH.
I've just done this:
IQueryable<Product> query = EntitySet.Where(p => p.Id == id);
Debug.WriteLine(query);
And the result shown in the Output:
SELECT
[Extent1].[Id] AS [Id],
[Extent1].[Code] AS [Code],
[Extent1].[Name] AS [Name],
[Extent2].[Id] AS [Id1],
[Extent2].[FileName] AS [FileName],
FROM [dbo].[Products] AS [Extent1]
INNER JOIN [dbo].[PersistedFiles] AS [Extent2] ON [Extent1].[PersistedFileId] = [Extent2].[Id]
WHERE [Extent1].[Id] = #p__linq__0
Entity Framework 4 Solution
Most of the answers here were EF6-specific. Here's one for those of you still using EF4.
This method replaces the #p__linq__0/etc. parameters with their actual values, so you can just copy and paste the output into SSMS and run it or debug it.
/// <summary>
/// Temporary debug function that spits out the actual SQL query LINQ is generating (with parameters)
/// </summary>
/// <param name="q">IQueryable object</param>
private string Debug_GetSQLFromIQueryable<T>(IQueryable<T> q)
{
System.Data.Objects.ObjectQuery oq = (System.Data.Objects.ObjectQuery)q;
var result = oq.ToTraceString();
List<string> paramNames = new List<string>();
List<string> paramVals = new List<string>();
foreach (var parameter in oq.Parameters)
{
paramNames.Add(parameter.Name);
paramVals.Add(parameter.Value == null ? "NULL" : ("'" + parameter.Value.ToString() + "'"));
}
//replace params in reverse order, otherwise #p__linq__1 incorrectly replaces #p__linq__10 for instance
for (var i = paramNames.Count - 1; i >= 0; i--)
{
result = result.Replace("#" + paramNames[i], paramVals[i]);
}
return result;
}
Starting from Entity Framework Core 5.0+ one can simply override the OnConfiguring method in the DbContext once for logging. This works also for Single() or Any() queries.
For logging to debug window:
public class ExampleDbContext : DbContext
{
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
// using System.Diagnostics;
optionsBuilder.LogTo(message => Debug.WriteLine(message));
}
}
For logging to console:
public class ExampleDbContext : DbContext
{
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.LogTo(Console.WriteLine);
}
}
See here for more details including log levels and filtering: https://learn.microsoft.com/en-us/ef/core/logging-events-diagnostics/simple-logging
If you want to have parameter values (not only #p_linq_0 but also their values) too, you can use IDbCommandInterceptor and add some logging to ReaderExecuted method.