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In EF Core 6, is there a way to see SQL that will be generated before SaveChanges() is called?

I know there is a way to see SQL that will be executed when querying for data from a database. For example, when query is created I can use query.ToQueryString() (based on this answer from SO):
var query = _context.Widgets.Where(w => w.IsReal && w.Id == 42);
var sql = query.ToQueryString();
But is there a way to see SQL that will be executed when SaveChanges() is called without actually executing SaveChanges()?
Code example that gets data from db and updates one field:
var context = new AppContext();
var author = context.Authors
.Include(a => a.Books)
.FirstOrDefault(a => a.AuthorId == 1);
// update some property
author.Books[0].BasePrice += 2;
// here I want to see SQL that will be generated to
// update the database when I call context.SaveChanges()
var sql = ...?

EF Core not tracking the correct property in a unit of work scenario

This question is an abstract of the problem that I am facing: consider the below,
I have entities with the following properties
public class Entity
{
public int Id { get; set; }
public int Status { get; set; }
}
Status can be 0 (New) or 1 (Deleted).
I have a service call which alters the entity from 0 -> 1 which is called through the service. The repository involved does not call context.SaveChanges(), instead this is handled farther up the chain in middleware.
This looks like:
var entity = await Context.Entities.FirstOrDefaultAsync(x => x.Id == id);
entity.SetDeleted();
Where the SetDeleted method changes the property from 0 to 1.
Then, in another service method (in the same unit of work) this is read to check if there is an entity which isn't deleted. This is where the problem occurs.
The code looks like:
var entities = context.Entities.Any(x => x.Status != 1);
Usually you would expect the graph to not be returned, but unfortunately it is. Strangely enough when you execute the ToList() function and then run the same operation it doesn't include the graph. This means that if you have the below:
var entities = await Context.Entities.Where(x => x.Status!= 1).ToListAsync();
var secondFilter = entities.Where(x => x.Status != 1).ToList();
The entities will contain the entity, the secondFilter will not contain the entity despite it being subject to the same rules.
Has anyone had this problem, does anyone know a solution?

This is by-design behavior of EF.
When you have a tracked entity, and query the same entity from the database, the tracked entity is never overwritten.
After
var entity = await Context.Entities.FirstOrDefaultAsync(x => x.Id == id);
entity.SetDeleted();
You have one tracked entity, with a modified Status.
This
var entities = await Context.Entities.Where(x => x.Status!= 1).ToListAsync();
Runs a SQL query and finds the same entity as its Status=0 in the database. But when when EF tries to add the entity to the change tracker it discovers that there's a modified version already there, and so it discards the data read from the database and adds the existing modified entity to the entities collection. Then this
var secondFilter = entities.Where(x => x.Status != 1).ToList();
returns nothing because entity has Status=1.

Entity framework query on just added but not saved values

I'm using Entity Framework from a couple of years and I have a little problem now.
I add an entity to my table, with
Entities.dbContext.MyTable.Add(obj1);
and here ok.
Then, I'd like to make a query on MyTable, like
Entities.dbContext.MyTable.Where(.....)
The code above will query on my MyTable in the db.
Is there a way to query also on the just added value, before the saveChanges? (obj1) How?
UPDATE
Why do I need this? Because, for each new element I add, I need to edit some values in the previous and the next record (there is a datetime field in this table)
UPDATE2
Let's say I have to add a lot of objects, but I call the saveChanges only after the last item is added. Every time I add the new item, I read its datetime field and I search in the database the previous and the next record. Here, I edit a field of the previous and of the next record. Now, here is problem: if I insert another item, and, for example, the next item is "Obj1", I have to find and edit it, but I can't find it since I haven't saved my changes. Is it clearer now?

You should be able to get your added entities out of the dbContext via the change tracker like this:
var addedEntities = dbContext.ChangeTracker.Entries()
.Where(x => x.State == EntityState.Added && x.Entity is Mytable)
.Select(x => x.Entity as MyTable)
.Where(t => --criteria--);
Or using the type testing with pattern matching in c# 7.0:
var addedEntities = dbContext.ChangeTracker.Entries()
.Where(x => x.State == EntityState.Added && x.Entity is Mytable t && --test t for criteria--)
.Select(x => x.Entity as MyTable);
because you are only querying added entities, you can combine this with
dbContext.MyTable.Where(t => --criteria--).ToList().AddRange(addedEntities);
to get all of the relevant objects

I think this is a good situation for Transactions. I am going to assume you are using EF 6 since you did not provide a version. =)
UPDATE2 changes
public void BulkInsertObj(List<TEntity> objList)
{
using (var context = new dbContext())
{
using (var dbContextTransaction = context.Database.BeginTransaction())
{
try
{
foreach(var obj1 in objList)
{
dbContext.MyTable.Add(obj1);
//obj1 should be on the context now
var previousEntity = dbContext.MyTable.Where(.....) //However you determine this
previousEntity.field = something
var nextEntity = dbContext.MyTable.Where(.....) //However you determine this
nextEntity.field = somethingElse
}
context.SaveChanges();
dbContextTransaction.Commit();
}
catch (Exception)
{
dbContextTransaction.Rollback();
}
}
}
}
MSDN EF6 Transactions

Why futures are not cached in session 1st level cache?

I have "static" readonly entities which I simply load with QueryOver<T>().List<T>(). All their properties are not "lazy". So some of them have N+1 problem.
I tried to use Future to avoid N+1. But it looks like then NH considers entity properties as "lazy". And when I access them it even reloads entities from db one by one (leading to the same N+1 situation) despite that all entities were preloaded preliminary and should be cached in the session 1st level cache. Here is the code how I'm doing it:
var futures = new List<IEnumerable>();
futures.Add(s.QueryOver<DailyBonus>().Future<DailyBonus>());
futures.Add(s.QueryOver<DailyBonusChestContent>().Future<DailyBonusChestContent>());
// ... other entities ...
// all queries should be sent with first enumeration
// but I want to ensure everything is loaded
// before using lazy properties
foreach (IEnumerable future in futures)
{
if (future.Cast<object>().Any(x => false)) break;
}
// now everything should be in cache, right?
// so I can travel the whole graph without accessing db?
Serializer.Serialize(ms, futures); // wow, N+1 here!
I checked this behavior using hibernatingrhinos profiler.
So what is going on wrong here?

The only correct way of using futures for loading entity with collections is with Fetch which means joins for each query:
var q = session.Query<User>().Where(x => x.Id == id);
var lst = new List<IEnumerable>
{
q.FetchMany(x => x.Characters).ToFuture(),
q.Fetch(x=>x.UpdateableData).ToFuture(),
session.QueryOver<User>().Where(x => x.Id == id)
.Fetch(x=>x.Characters).Eager
.Fetch(x => x.Characters.First().SmartChallengeTrackers).Eager
.Future()
};
var r = session.QueryOver<User>().Where(x => x.Id == id)
.TransformUsing(Transformers.DistinctRootEntity)
.Future();
foreach (IEnumerable el in lst)
{
foreach (object o in el)
{
}
}
return r.ToArray();
It's still better than join everything in a one query - NHibernate won't have to parse thousands of rows introduced by join x join x join x join...
You can add normal select queries (without Fetch) to to the same batch but they won't be used for retrieving collections on another entity.

Linq to SQL Updating Data

I am just starting to use linq to sql for data access. It is working fine for read only. But it does not work for update. I have been reading the threads over several forums. It is clear that anonymous types (in my case var) cannot be updated. I cannot find what I should replace the var with and where I find it. I will appreciate any help.
Below is the code. The exception is
Error 1 Property or indexer 'AnonymousType#1.date_last_logon' cannot be assigned to -- it is read only
fmcsaDataContext db = new fmcsaDataContext();
// DataTable _UserTable;
UserModel _UserModel = new UserModel();
var users = from u in db.FMCSA_USERs
where u.USER_NAME == pName && u.ACTIVE == true
select new
{
date_last_logon = u.DATE_LAST_LOGON,
date_current_logon = u.DATE_CURRENT_LOGON,
failed_login = u.FAILED_LOGIN,
};
if (users.Count() == 0)
return null;
foreach (var user in users)
{
user.date_last_logon = user.date_current_logon;
}

This is the case for any ORM tool; you will have to use the entity types that LINQ-to-SQL generates for you when you make your .dbml file if you want to perform CRUD operations.
Also, be aware that your query is being executed twice and is not concurrently safe; calling Count() executes your query with a Count aggregate in the database, then looping over it executes the query again, this time bringing back results. Given what you're doing, this may be better:
var users = (from u in db.FMCSA_USERs
where u.USER_NAME == pName && u.ACTIVE == true
select u).ToList(); // This executes the query and materializes
// the results into a List<FMCSA_USER>
if (users.Count == 0) return null;
foreach (var user in users)
{
user.date_last_logon = user.date_current_logon;
}
db.SaveChanges();

In order to update data, you cannot use anonymous types.
Instead, you can end your query with select u; to select the actual entities.

Table you are trying to update using LINQ, should have Primary key.