The ambiguity appears that you have the DevArt EF Core provider installed and setup with your app along with Oracle EF Core. Both providers implement UseOracle() and EF Core doesn't know which one you actually want to use.

Thanks for reply - removing devart worked in resolving ambiguity and solution builds o.k.

However, get error message below when tried to run it.

System.ArgumentException: 'AddDbContext was called with configuration, but the context type 'RazorPagesMultipleContext' only declares a parameterless constructor. This means that the configuration passed to AddDbContext will never be used. If configuration is passed to AddDbContext, then 'RazorPagesMultipleContext' should declare a constructor that accepts a DbContextOptions<RazorPagesMultipleContext> and must pass it to the base constructor for DbContext.'

  services.AddDbContext<RazorPagesMultipleContext>(options =>

                 //  options.UseSqlServer(Configuration.GetConnectionString("RazorPagesMultipleContext")));

                   options.UseOracle(Configuration.GetConnectionString("RazorPagesMultipleContext")));

How can we call the context successfully or how should we define below in context

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)

        {

            optionsBuilder.UseOracle(@"User Id = <userid>; Password = <pwd>; Data Source = <server>:1521/<SID>;");

        }

Thanks

This SO thread should be useful in helping you resolve this new issue:

https://stackoverflow.com/questions/45947795/adddbcontext-was-called-with-configuration-but-the-context-type-mycontext-o…

Thanks.

Now the solution builds successfully.

However, web page doesn't launch anymore.

works with local sqlserver however when try and use oracle it is no longer launching

called from startup.cs - only diff with oracle one is bits in bold

Any thought as to why not working - anything else missing to get this to work with oracle.

based on https://docs.microsoft.com/en-us/aspnet/core/tutorials/razor-pages/?view=aspnetcore-2.2 and just trying to use oracle rather than local sql server database

            services.AddDbContext<RazorPagesMultipleContext>(options =>

                 //  options.UseSqlServer(Configuration.GetConnectionString("RazorPagesMultipleContext")));

                   options.UseOracle(Configuration.GetConnectionString("RazorPagesMultipleContext")));

context definition below.

using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

using Oracle.EntityFrameworkCore;

using Microsoft.EntityFrameworkCore;

namespace RazorPagesMultiple.Models

{

    public class RazorPagesMultipleContext : DbContext

    {

         public RazorPagesMultipleContext (DbContextOptions<RazorPagesMultipleContext> options)

              : base(options)

          {

           }

        public DbSet<RazorPagesMultiple.Models.Multiple> Multiple { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)

        {

            optionsBuilder.UseOracle(@"User Id = <uname>; Password = <pwd>; Data Source = <server>:1521/<SID>;");

        }

    }

}

Getting message below now despite fact can tnsping <SID> from command prompt on my pc

Anything else need to set up to get it working with oracle

An unhandled exception occurred while processing the request.

NetworkException: ORA-12154: TNS:could not resolve the connect identifier specified

OracleInternal.Network.AddressResolution..ctor(string TNSAlias, string instanceName)

OracleException: ORA-12154: TNS:could not resolve the connect identifier specified

OracleInternal.ConnectionPool.PoolManager<PM, CP, PR>.Get(ConnectionString csWithDiffOrNewPwd, bool bGetForApp, OracleConnection connRefForCriteria, string affinityInstanceName, bool bForceMatch)

Already have a TNS_ADMIN environment variable on pc but thinking something else must be needed to get oracle working with ef core.

Managed to get further

Needed to use

optionsBuilder.UseOracle(@"User Id = <uname>; Password = <pwd>; Data Source = <SID>;");

However get message table or view does not exist.

On database table name is all upper case but ef core generating sql below in mixed case.

believe problem is that ef core is generating sql with quotation marks - how can this be stopped to allow this to work?

   at Oracle.EntityFrameworkCore.Storage.Internal.OracleRelationalCommandBuilderFactory.OracleRelationalCommandBuilder.OracleRelationalCommand.ExecuteAsync(IRelationalConnection connection, DbCommandMethod executeMethod, IReadOnlyDictionary`2 parameterValues, CancellationToken cancellationToken)

Microsoft.EntityFrameworkCore.Database.Command:Error: Failed executing DbCommand (137ms) [Parameters=[], CommandType='Text', CommandTimeout='0']

SELECT "m"."MULT_MULTIPLE_CODE", "m"."MULT_ANMW_MULTIPLE_CODE", "m"."MULT_AUTH_REQUIRED", "m"."MULT_JMW_MULTIPLE_TYPE_CODE", "m"."MULT_LINK_MULTIPLE_CODE", "m"."MULT_NAME", "m"."MULT_PROM_AUTH_REQUIRED", "m"."MULT_SELECTED_MULTIPLE"

FROM "Multiple" "m"

Will start a new thread as looks like have got past first set of issues and now just looking to how can avoid ef core generating quoting which is causing table or view does not exist error

I've been trying to take advantage of Oracle.EntityFrameworkCore v3.19 provider for .NetCore.
I've followed Oracle's tutorial in terms of testing these features together. With just a couple classes, a dbSet of those classes. And in the main function I try to add a instance of a class to the DbSet, and try to SaveChanges().
I've also created the tables for those couple classes in my Database schema.
But everytime i run it get an Exception (at the db.SaveChanges(); line):
OracleException: ORA-06550: line 13, column 14: PL/SQL: ORA-00942: table or view does not exist ORA-06550: line 13, column 1: PL/SQL: SQL Statement ignored
Please let me know if there's something i can try to move on from this.

I would recommend turning on tracing to see what SQL is being executed when the error occurs. That will tell you the name of the table or view EF Core is trying to use.