How to Create a Constant Value of Type Only Primitive Types or Enumeration Types Are Supported in This Context

Unable to create a constant value of type Only primitive types or enumeration types are supported in this context

This cannot work because ppCombined is a collection of objects in memory and you cannot join a set of data in the database with another set of data that is in memory. You can try instead to extract the filtered items personProtocol of the ppCombined collection in memory after you have retrieved the other properties from the database:

var persons = db.Favorites
    .Where(f => f.userId == userId)
    .Join(db.Person, f => f.personId, p => p.personId, (f, p) =>
        new // anonymous object
        {
            personId = p.personId,
            addressId = p.addressId,   
            favoriteId = f.favoriteId,
        })
    .AsEnumerable() // database query ends here, the rest is a query in memory
    .Select(x =>
        new PersonDTO
        {
            personId = x.personId,
            addressId = x.addressId,   
            favoriteId = x.favoriteId,
            personProtocol = ppCombined
                .Where(p => p.personId == x.personId)
                .Select(p => new PersonProtocol
                {
                    personProtocolId = p.personProtocolId,
                    activateDt = p.activateDt,
                    personId = p.personId
                })
                .ToList()
        });

LINQ Query error: Unable to create a constant value of type. Only primitive types or enumeration types are supported in this context

endedContracts is an in memory list and cannot be used directly in this query. Instead, get the value you need outside of the query, for example:

//Get the code here
var brokerCode = endedContracts.First().Broker.Code;

var crystallisedCommissions = _context.Contracts
   .Where(x => x.Statement.Sent)
   .Where(x => x.Statement.Broker == brokerCode) //Use the code here
   .Where(x => !Period.IsPeriodBeforeReferencePeriod(x.Statement.Period, CUT_OFF_PERIOD))
   .Where(x => endedContracts.Any(y => y.Contract.Identifier == x.Identifier
                                    && y.Contract.StartDate == x.ContractStartDate
                                    && y.Contract.EndDate == x.ContractEndDate)).ToList();

EF - Unable to create a constant value of type Only primitive types or enumeration types are supported in this context

When I run it this way:

dbc.PickupLocations.Where(pl => pl.ShippingProfileCountryID != 796 && !activeLockers.Select(al => al.LockerId).ToList().Contains(pl.ExternalID))
                                   .ToList()
                                   .ForEach(x => x.Status = 0);

dbc.SaveChanges();

I get this error:

Unable to create a constant value of type Only primitive types or
enumeration types are supported in this context

But like this it works:

var activeLockersIDs = activeLockers.Select(al => al.LockerId).ToList();
dbc.PickupLocations.Where(pl => pl.ShippingProfileCountryID != 796 && !activeLockersIDs.Contains(pl.ExternalID))
                                   .ToList()
                                   .ForEach(x => x.Status = 0);

dbc.SaveChanges();

I read about this error here:
Unable to create a constant value of type Only primitive types or enumeration types are supported in this context

But I am still not sure what was the exact problem, if someone understands and can explain in the comments it would be good to know.

Unable to create a constant value of type 'x'. Only primitive types or enumeration types are supported in this context

        public List<VisaCodesNamesDto> GetVisaCodesNames(List<VisaCodesNamesInputDto>input)
    {


        List<string> filterlist = input.Select(x => x.VisaId.ToString() + "-" + x.VersionNo).ToList();


        var result = (from visaConfigurationDocuments in Context.VisaConfigurationDocuments
                      join visaCodes in Context.VisaCodes
                      on visaConfigurationDocuments.VisaCodeId equals visaCodes.VisaCodeId
                      where filterlist.Any(x => x == visaConfigurationDocuments.VisaId.ToString() + "-" + visaConfigurationDocuments.VersionNo)
                      select new VisaCodesNamesDto
                      {
                          VisaCodeNameAr = visaCodes.NameAr,
                          VisaCodeNameEn = visaCodes.NameEn,
                          VisaId = visaConfigurationDocuments.VisaId,
                          VersionNo = visaConfigurationDocuments.VersionNo
                      }).ToList();

        return result;}

i make a work around solution that solve my issue in converting type of complex object in where clause

Error: Only primitive types or enumeration types are supported in this context EF

You use a local collection, Subscribers, directly in a LINQ statement. But these objects can't be translated into SQL. There are only mappings from primitive types to database types.

I'd suggest you use

var emails = Subscribers.Select(s => s.Email).ToList();

And proceed by using these strings (i.e. primitive values) in Contains statements like:

var newSubscribers = db.Subscriber
                       .Where(dbSub => !emails.Contains(dbSub.Email))
                       .ToList();
var updateSubscribers = db.Subscriber
                          .Where(dbSub => emails.Contains(dbSub.Email))
                          .ToList();