Python Losing Class Reference

Question

I need help with a class reference problem. My class is losing the reference in the middle of a While and I’m not getting to figure out why. Gives the following message:

Erroinstance '' has been Deleted, or its Row is otherwise not present.

I will post the code. In summary it reads a file and depending on the record type record it may have 1 or more records. The fact is that when leaving an IF and entering the next one the class that was instantiated loses the reference. I imagine it’s not something complex, but I’m not able to find the point. In the code is the comment #Here comes the error to inform the place where it is not working. If someone can give me a force I thank. Follow the code, thank you:

def importFile(self, url, file):  
    try:            
        url = url+"/"+file            
        fileImport = open(url, 'r')
        lines = fileImport.readlines()            
        fileImport.close()         
        banco = Banco()

        i = 0        

        while i < len(lines):                                                                                                
            line = lines[i].replace("\n","").split("|") # ler a linha do fileOriginal, retira os \n e troca , por .

            if line[0] == '00000':
                id_02000 = 0
                id_03110 = 0                
                id_03111 = 0
                id_03112 = 0
                id_03120 = 0
                id_03121 = 0
                id_03122 = 0
                id_03130 = 0
                id_03131 = 0
                id_03132 = 0
                id_04000 = 0
                pgdasd = Pgdasd()
                pgdasd = pgdasd.setPgdasd_00000(line)                          
                id_declaracao = pgdasd.PGDASD_00000_ID_DECLARACAO                    
                banco.insere(pgdasd, i+1)               

            if line[0] == '03000':#Pode repetir                                
                pgdasd_03000 = Pgdasd_03000()
                pgdasd_03000.setPgdasd_03000(line, id_declaracao)                    

                banco.insere(pgdasd_03000, i+1)

            if line[0] == '03100':#Se repete
                pgdasd_03100 = Pgdasd_03100() #Essa classe é usada no próximo IF
                pgdasd_03100.setPgdasd_03100(line, id_declaracao, pgdasd_03000)                    

                banco.insere(pgdasd_03100, i+1)

            if line[0] == '03110':#Se repete
                id_03110 = id_03110+1
                pgdasd_03110 = Pgdasd_03110()
                pgdasd_03110.setPgdasd_03110(line, id_declaracao, pgdasd_03000, pgdasd_03100, id_03110) #Aqui dá o erro

                banco.insere(pgdasd_03110, i+1)                

            i = i + 1  
        banco.fechaSessao()
        print("Arquivo "+url+" importado com sucesso")             
    except Exception as e:                 
        exit()

Classes:

Base = declarative_base()

class Pgdasd_03100(Base):
__tablename__  = 'pgdasd_03100'
__table_args__ = SCHEMA

PGDASD_00000_ID_DECLARACAO   = Column(String, primary_key = True)
PGDASD_03000_CNPJ            = Column(String, primary_key = True)    
PGDASD_03100_TIPO            = Column(String(2), primary_key = True)
PGDASD_03100_VLTOTAL         = Column(Numeric(14,2))


def setPgdasd_03100(self, line, id_declaracao, pgdasd_03000):                       
    self.PGDASD_00000_ID_DECLARACAO = id_declaracao
    self.PGDASD_03000_CNPJ          = pgdasd_03000.PGDASD_03000_CNPJ
    self.PGDASD_03100_TIPO          = line[1]
    self.PGDASD_03100_VLTOTAL       = line[2]

    return self

class Pgdasd_03110(Base):
__tablename__  = 'pgdasd_03110'    
__table_args__ = SCHEMA    

PGDASD_00000_ID_DECLARACAO   = Column(String, primary_key = True)
PGDASD_03000_CNPJ            = Column(String, primary_key = True)    
PGDASD_03100_TIPO            = Column(String, primary_key = True)
PGDASD_03110_ID              = Column(Integer, primary_key = True)
PGDASD_03110_UF              = Column(String(2))
PGDASD_03110_COD_TOM         = Column(String(4))
PGDASD_03110_VALOR           = Column(Numeric(14,2))    


def setPgdasd_03110(self, line, id_declaracao, pgdasd_03000, pgdasd_03100, id_03110):

    self.PGDASD_00000_ID_DECLARACAO   = id_declaracao
    self.PGDASD_03000_CNPJ            = pgdasd_03000.PGDASD_03000_CNPJ 
    self.PGDASD_03100_TIPO            = pgdasd_03100.PGDASD_03100_TIPO

    self.PGDASD_03110_ID              = id_03110            
    self.PGDASD_03110_UF              = line[1]
    self.PGDASD_03110_COD_TOM         = line[2]
    self.PGDASD_03110_VALOR           = line[3]        

    return self