@api.depends('num_prospect')

def_compute_prospect(self):

    for record in self:

        last_prospect =self.search([], limit=1, order="id asc") 

        record.num_prospect =int(last_prospect.num_prospect) +1

Do this changes to the code but isn't work very well, the first to prospects i created was good, the first one with the value 1 and the second one with the value 2, but after that, all the prospects i created have the number 2 in num_prospec field. 

Hi @Guilherme

Please try below code:

@api.depends('num_prospect')
def _compute_prospect(self):
for record in self:
# get the last record and add + 1 to its num_prospect
# If no records exist the num_prospect = 1 by default
last_prospect = self.search([], limit=1, order="id desc")
record.num_prospect = last_prospect and int(last_prospect.num_prospect) + 1 or 1


Hope this solves your query.

Thanks & Regards,
Email: odoo@aktivsoftware.com
Skype: kalpeshmaheshwari