Data migration in code first error using postgresql as database in .net core 3.0 - postgresql

Question

I am migrating data using code first approach and db is postgresql, on add-migration is working fine,but update-database is giving error as"42601: syntax error at or near "GENERATED", more details below:
> PM> add-migration migration
> Build started...
> Build succeeded.
> To undo this action, use Remove-Migration.
> PM> update-database
> Build started...
> Build succeeded.
> [15:18:48 Error] Microsoft.EntityFrameworkCore.Database.Command
> Failed executing DbCommand (298ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
> CREATE TABLE "Customers" (
> "CustomerId" integer NOT NULL GENERATED BY DEFAULT AS IDENTITY,
> "CustomerName" text NULL,
> CONSTRAINT "PK_Customers" PRIMARY KEY ("CustomerId")
> );
>
> Npgsql.PostgresException (0x80004005): 42601: syntax error at or near "GENERATED"
> at Npgsql.NpgsqlConnector.<>c__DisplayClass160_0.<<DoReadMessage>g__ReadMessageLong|0>d.MoveNext()
> --- End of stack trace from previous location where exception was thrown ---
> at Npgsql.NpgsqlConnector.<>c__DisplayClass160_0.<<DoReadMessage>g__ReadMessageLong|0>d.MoveNext()
> --- End of stack trace from previous location where exception was thrown ---
> at Npgsql.NpgsqlDataReader.NextResult(Boolean async, Boolean isConsuming)
> at Npgsql.NpgsqlDataReader.NextResult()
> at Npgsql.NpgsqlCommand.ExecuteReaderAsync(CommandBehavior behavior, Boolean async, CancellationToken cancellationToken)
> at Npgsql.NpgsqlCommand.ExecuteNonQuery(Boolean async, CancellationToken cancellationToken)
> at Npgsql.NpgsqlCommand.ExecuteNonQuery()
> at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteNonQuery(RelationalCommandParameterObject
> parameterObject)
> at Microsoft.EntityFrameworkCore.Migrations.MigrationCommand.ExecuteNonQuery(IRelationalConnection
> connection, IReadOnlyDictionary`2 parameterValues)
> at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.ExecuteNonQuery(IEnumerable`1
> migrationCommands, IRelationalConnection connection)
> at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String
> targetMigration)
> at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String
> targetMigration, String contextType)
> at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabaseImpl(String
> targetMigration, String contextType)
> at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase.<>c__DisplayClass0_0.<.ctor>b__0()
> at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action
> action)
> Exception data:
> Severity: ERROR
> SqlState: 42601
> MessageText: syntax error at or near "GENERATED"
> Position: 63
> File: src\backend\parser\scan.l
> Line: 1067
> Routine: scanner_yyerror
> 42601: syntax error at or near "GENERATED"
(As this is code first approach so, below are the model)
Model:
public class Customer1
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int CustomerId { get; set; }
public string CustomerName { get; set; }
}
**Update: Got a solution:
in migrationbuilder(created after add-migration command),i simply changed**
NpgsqlValueGenerationStrategy.IdentityByDefaultColumn
to
NpgsqlValueGenerationStrategy.serialcolumn
**and saved it ,and then run the command update-database ,and it worked**

Answer 1

You seem to be activating the IDENTITY columns feature, which was only introduced in PostgreSQL 10.(while you are 9.4.20)
I suggest that you could upgrade to a newer version of PostgreSQL.
Refer to https://dba.stackexchange.com/questions/198777/how-to-add-a-postgresql-10-identity-column-to-an-existing-table

Answer 2

Seriously! I doubt it's Postgres 3.x anything (released in '91). That may be your .net version. Please run this query: select version();
Your table definition uses "GENERATED BY DEFAULT AS IDENTITY". This initially appeared in version 10. If your version less then change that definition to:
create table Customers (
CustomerId serial
CustomerName text null,
constraint pk_customers primary key (CustomerId)
);
Note: I've removed the double quotes (") and would suggest you do the same. They just are not worth the trouble they cause.