How to read dictionary variable in 0/U file in OpenFOAM

I wanted to read the viscosity variable "nu" of "transportProperties" dictionary in the inlet boundary in 0/U as follows:

boundaryField
{
    inlet
    {
        type    codedFixedValue;
        value   uniform (0.006 0 0);
        name    parabolicInlet;
        code
        #{
               // ... some lines of code ...
               scalar nu = readScalar(this->db().lookupObject<IOdictionary>("transportProperties").lookup("nu"));
              // ... some lines of code ...
        #};
    }
}

and I got this this wrong token type error:

--> FOAM FATAL IO ERROR:
wrong token type - expected Scalar, found on line 22 the punctuation token '['

file: /home/behzadb/research/Simulations/ConfinedCylinder2D/TestCase-01/constant/transportProperties/nu at line 22.

    From function Foam::Istream& Foam::operator>>(Foam::Istream&, Foam::doubleScalar&)
    in file lnInclude/Scalar.C at line 101.

FOAM exiting

I would appreciate knowing how I should call the dictionary and read that dimensioned scalar variable "nu" from it to use for some calculations (like the Reynolds number)?

Thanks a lot, BB

Try the following:

boundaryField
{
    inlet
    {
        type    codedFixedValue;
        value   uniform (0.006 0 0);
        name    parabolicInlet;
        code
        #{
            // ... some lines of code ...

            dimensionedScalar nu
            (
               "nu",
               dimViscosity,
               this->db().lookupObject<IOdictionary>("transportProperties").lookup("nu")
            );

            // ... some lines of code ...
        #};
    }
}

You are getting that error because you're trying to read the kinematic viscosity as a scalar. Instead, use a dimensionedScalar.

If you would like to use the scalar value of nu, you can access it with:

scalar nu_value = nu.value();