I tried to evaluate a python code that i write it in a text field.

this is the error that i face

TypeError: unsupported operand type(s) for %: 'ValidationError' and 'exceptions.ValueError'

First of all i have this class condition:

class condition(models.Model):
    _name = 'condition'


    expression_cond = fields.Selection(
        string="Expression",
        selection=[('python', 'Expression  Python'), ],
        required=True,
        default="python")

    value_cond = fields.Text(
        string="Valeur",
        required=True,
        default="""
# Python code.
# You can use the following variables :
#  - self: ORM model of the record which is checked
#  - object: same as order or line, browse_record of the sale order or
#  - pool: ORM model pool (i.e. self.pool)
#  - cr: database cursor
#  - context: current context
#  - invoice: test for invoice tests
# Note: returned value have to be set in the variable 'result'
"""
    )

    name = fields.Char(string="Condition", required=True, )

The second class is the rules; i create this calss to select a condition and to verifier if the python expression is correct

class rules(models.Model):
    _name = 'rules'

    name = fields.Char(string="Régles" ,required=True)
    code = fields.Char(string="Code" ,required=True)
    condition_id = fields.Many2one(comodel_name="condition", string="Condition ", required=True, )
    amount_type_id = fields.Many2one(comodel_name="amount.type", string="Méthode de Calcul", required=True, )

i create those method in this class

@api.model
def _rules_eval_context(self, obj_name, rec):
    invoice = self.env['account.invoice']
    return {obj_name: rec,
            'invoice': invoice,
            'self': self.pool.get(rec._name),
            'object': rec,
            'obj': rec,
            'pool': self.pool,
            'cr': self._cr,
            'uid': self._uid,
            }

@api.model
def _rule_eval(self,rule, obj_name, rec):
    rule =self.condition_id.value_cond
    expr = rule
    space = self._rules_eval_context(obj_name, rec)
    
)

    try:
        safe_eval(expr,
                  space,
                  mode='exec',
                  nocopy=True)  # nocopy allows to return 'result'
    except Exception as  e:
        raise   ValidationError("Wrong python code defined for Condition : %s") % (e)  
    return space.get('result', False)

@api.onchange('condition_id')
def _detect_rules(self):

    rule = self.condition_id.value_cond 
    if self._rule_eval(rule,'invoice', self):
        print("*****dectect rules")
    else:
        print("*********wrong detection")

 this is my expression that i creat 

if invoice.amout_total >=1000 :
    result=True

 you can find the pictures on this link

https://drive.google.com/drive/folders/0BwRD3KEH7ZiVS0VFemxTNjJkSHc?usp=sharing

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