dotnet ef scaffold Unrecognized option '-t firstTable -t secondTable'

August 2, 2022

I have a .ps1 file that I run from PowerShell, the code is as follows:

$strTables = ""
$tables | ForEach-Object{            
    $strTables += "-t $_ "  
}
# $strTables = -t fisrtTable -t secondTable
dotnet ef dbcontext scaffold $strConn Npgsql.EntityFrameworkCore.PostgreSQL --context MyModel $strTables -v -f

If I put the variable $strTable in the command it does not recognise the -t parameter (but the variable $strConn does work)

Unrecognized option '-t fisrtTable -t secondTable'

If I write the tables without the variable, it works.

dotnet ef dbcontext scaffold $strConn Npgsql.EntityFrameworkCore.PostgreSQL --context MyModel -t firstTable -t secondTable -v -f

I have too many tables to do this manually. Do you know how I can concatenate variable $strTables with the dotnet command?

Thanks in advance

>Solution :

If you construct a string such as -t foo and pass it via a variable to an external program, it is passed as a single, double-quoted argument (that is, donet will see "-t foo" on its command line) – and therefore won’t be recognized as parameter name-value combination.

You must pass -t and foo separately, as elements of an array instead.
When you use an array as an argument for an external program, PowerShell passes the array elements as individual, space-separated arguments:

# Create an array such as '-t', 'foo', '-t', 'bar', ...
$tableArgs = 
  $tables | ForEach-Object{            
    '-t', "$_"  
  }

# Note the use of $tableArgs as-is, which causes PowerShell to pass
# something like -t foo -t bar behind the scenes.
dotnet ef dbcontext scaffold $strConn Npgsql.EntityFrameworkCore.PostgreSQL --context MyModel $tableArgs -v -f