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Using a list of classes as a model for table class in django_tables2

I tried to create a table using a class that is not related to my database in django and this class is stored in models.py as shown below (InfoServer is the class). What I wanted to do is to use this class to populate my table using django_tables2. Add models.Model as a parameter is not an option because I don't want to save this class in the database.
Whenever I define the model = InfoServer in tables.py I got this error and I suppose it's because InfoServer did not take models.Model as a parameter.
TypeError: descriptor 'repr' of 'object' object needs an argument
Any help is appreciated.
models.py
class TestServeur(models.Model):
nom = models.CharField(max_length=200)
pid = models.CharField(max_length=200)
memoire = models.IntegerField(null=True)
class InfoServer:
# "This is a class to test my knowledge of python"
def __init__(self,p = '',c = 0,m = 0):
self.pid = p
self.cpu = c
self.memoire = m
def getData(self):
return ("A server with %s memory and %s cpu" % (self.cpu,self.memoire))
views.py
def index(request):
return HttpResponse("Hello, world. You're at the index.")
def cpu_view(request):
liste = []
proc1 = Popen(['ps','-eo','pid,%cpu,%mem,comm'], stdout=PIPE, stderr=PIPE)
proc2 = Popen(['grep','java'], stdin=proc1.stdout, stdout=PIPE)
proc1.stdout.close()
for line in iter(proc2.stdout.readlines()):
clean_line = line.decode("utf-8")
info_utiles = clean_line.split()
pid,cpu,mem,*rest = info_utiles
i1 = InfoServer(pid,cpu,mem)
liste.append(i1)
table = TestServeur(liste)
RequestConfig(request).configure(table)
return render(request, 'server/cpu.html', {'output': table})
tables.py
class TableServeur(tables.Table):
class Meta:
# model = InfoServer
fields = ['pid', 'memory', 'cpu']
template_name = 'django_tables2/bootstrap4.html'

As I can see, InfoServer class is not a Django Model. Also I don't think you need to use that directly anyway. So, you can simply provide a list with dictionary, and render it in template with table.
First, we need to update Table class and remove Meta class from it, as we are not going to use any django models.
class TableServeur(tables.Table):
pid = tables.Column()
memory = tables.Column()
cpu = tables.Column()
Now, adding a new object method to return dictionary from InfoServer class:
class InfoServer:
# "This is a class to test my knowledge of python"
def __init__(self,p = '',c = 0,m = 0):
self.pid = p
self.cpu = c
self.memoire = m
def getData(self):
return ("A server with %s memory and %s cpu" % (self.cpu,self.memoire))
def get_dict_data(self):
return {'pid': self.pid, 'cpu': self.cpu, 'memory': self.memoire}
Finally, update the view:
for line in iter(proc2.stdout.readlines()):
clean_line = line.decode("utf-8")
info_utiles = clean_line.split()
pid,cpu,mem,*rest = info_utiles
i1 = InfoServer(pid,cpu,mem)
liste.append(i1.get_dict_data())
table = TestServeur(liste)
return render(request, 'server/cpu.html', {'output': table})
More info can be found in documentation on how you can populate table with data.

How to filter django model based on other non related model

Please refer to the code below
Transaction models
class Transaction(models.Model)
current_product_code = models.CharField(....)
previous_product_code = models.CharField(....)
#property
def status(self):
c_price = Product.objects.get(code=self.current_product_code).price
p_price = Product.objects.get(code=self.previous_product_code).price
if c_price == p_price:
return "Due"
elif c_price > p_price:
return "Upgrade"
else:
return "Downgrade"
Product model
class Product(models.Model):
code = models.CharField(....)
price = models.DecimalField(....)
My question: How can i obtain/filter transactions with upgrade/downgrade/due status. I am trying to create a custom admin filter which filter transaction based on their status but i fail what to put inside .filter() , check the method below
def queryset(self, request, queryset):
value = self.value()
if value == 'Upgrade':
return queryset.filter(***** HERE *****)
elif value == 'Downgrade':
return queryset.filter(***** HERE *****)
elif value == 'Unknown':
return queryset.filter(***** HERE *****)
return queryset

You really should use ForeignKey between Product and Transaction (for both: current_product_code and previous_product_code). This will allow you to use those relations in your querysets with ease.
My proposed models structure looks like this:
class Product(models.Model):
code = models.CharField(....)
price = models.DecimalField(....)
class Transaction(models.Model)
# You have to define related_name for at least one of relations below.
# Without that, automatically generated ones will clash.
# Also don't foget to change `on_delete` to suit your needs.
current_product = models.ForeignKey(Product, related_name="current_transactions", on_delete=models.CASCADE)
previous_product = models.ForeignKey(Product, related_name="previous_transactions", on_delete=models.CASCADE)
#property
def status(self):
# also, no need to do additional queries here manually. You can improve
# it further by using `select_related` when querying for transactions.
c_price = self.current_product.price
p_price = self.previous_product.price
if c_price == p_price:
return "Due"
elif c_price > p_price:
return "Upgrade"
else:
return "Downgrade"
With that model structure, finding specific types of transactions will be easier:
upgrade_transactions = Transaction.objects.filter(current_product__price__gt=F('previous_product__price'))
downgrade_transactions = Transaction.objects.filter(current_product__price__lt=F('previous_product__price'))
due_transactions = Transaction.objects.filter(current_product__price=F('previous_product__price'))

I think you could try to use Subquery, OuterRef and .annotate():
if value == 'Upgrade':
return queryset.annotate(
previous_price=Subquery(
Product.objects.filter(
code=OuterRef("previous_product_code")
)[:1]
),
current_price=Subquery(
Product.objects.filter(
code=OuterRef("current_product_code")
)[:1]
),
).filter(current_price__gt=F("previous_price"))
...

Remember that filter() operation, in the end, is a SQL operation and we should take care on the performance issues.
So my advice is: if you need to filter by status, update the status on Product model everytime a transaction is saved. Your application will be faster and will have a cleaner code.

Flask-SQLAlchemy adds unnecessary row in parents table (relational tables)

I'm recently trying to build a little web-app with Flask. For the database 'stuff' I use Flask-SQLAlchemy and now I'm trying to get a relationship between two objects going.
I have a 'project' table and a 'file' table and it should be a one-to-many relation, so x files can be associated with one project (actually there are more relations coming in the future when I've figured the current problem out).
I've made a input-mask template so a user can upload a file and link it to a project via a dropdown which is populated with the existing projects stored in its table. Thats the corresponding view:
#app.route('/admin/upload/', methods=('GET', 'POST'))
def upload():
form = forms.UploadForm()
if not os.path.isdir(app.config['UPLOAD_FOLDER']):
os.mkdir(app.config['UPLOAD_FOLDER'])
print('Folder created')
form.projectId.choices = []
for g in models.Project.query.order_by('name'):
form.projectId.choices.append((g.id, g.name))
if form.validate_on_submit():
filename = secure_filename(form.fileUpload.data.filename)
filepath = os.path.join(app.config['UPLOAD_FOLDER'], filename)
assocProject = models.Project(name=models.Project.query.filter_by(id=form.projectId.data).first().name)
form.fileUpload.data.save(filepath)
prepedFile = models.File(path=filepath, project=assocProject)
print(prepedFile)
print(form.projectId.data)
db.session.add(prepedFile)
db.session.commit()
return 'success'
else:
filename = None
return render_template('upload.html', form=form, filename=filename)
The prepared file should be an instance of the File-Class which has the linked Project-instance as an attribute, therefore the commit should work.
class Project(db.Model):
__tablename__ = 'project'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(64))
file = db.relationship('File', backref="projects")
post = db.relationship('Post', backref="projects")
def __init__(self, name):
self.name = name
def __repr__(self):
return '<Project %r>' % self.name
class File(db.Model):
__tablename__ = 'file'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(64))
path = db.Column(db.String(64))
type = db.Column(db.String(6))
projectId = db.Column(db.Integer, db.ForeignKey('project.id'))
project = db.relationship('Project', backref='files')
def __init__(self, path, project):
self.path = path
self.project = project
fullName = re.search('[a-zA-Z0-9]*\.[a-zA-Z]{2,}', path)
splitName = fullName.group(0).split('.')
self.name = splitName[0]
self.type = splitName[1]
def __repr__(self):
return '<File %r %r %r %r>' % (self.name, self.type, self.path, self.project)
And now the problem: When I try to upload a file it works and the file information are stored in the file table but it creates a new entry in the project table and link its id to the file entry. E.g., if the project entry looks like: name = TestProj1, id=1 and I try to link the uploaded to the project it will create a second project: name = TestProj1, id=2.
Thats my struggle and I cant figure out whats wrong. Maybe some of you now. I appreciate any help!
P.S. Maybe it is relevant, here the form I wrote:
class UploadForm(Form):
fileUpload = FileField(label='Deine Datei')
projectId = SelectField(u'Projekte', coerce=int)

You create a new Project each time.
assocProject = models.Project(name=models.Project.query.filter_by(id=form.projectId.data).first().name)
This does two things. First, it finds the first project with the specified id. Second, it passes that project's name to Project(), creating a new instance using that same name.
What you really want is
assocProject = models.Project.query.get(form.projectId.data)

No reference id found for related field odoo 8

I am trying to relate many2one field to another many2one field but return error.
I used on create method didn't work, I tried
jounral = field.Many2one('erp.journal', related="journal_item.journal
worked but on upgrade of database I receive error
There is no reference field journal_id found of journal.entries.
Here is my code
class JournalItem(models.Model):
_name = 'journal.item'
name = fields.Char()
journal = fields.Many2one('erp.journal')
entries = fields.One2many('journal.entries', 'journal_item')
class JournalEntries(models.Model):
_name = 'journal.entries'
#record Created but didn't work
#api.model
def create(self, vals):
vals['journal_id'] = self.journal_item.journal
return super(JournalEntries, self).create(vals)
#Error NoneType object has no attribute 'id'
#api.model
def create(self, vals):
for x in self:
x.journal_id = x.journal_item.journal
return super(JournalEntries, self).create(vals)
journal_item = fields.Many2one('journal.item')
journal_id = fields.Many2one('erp.journal')

Very first you need to understand the #api decorators usage, which decorators should be implemented when.
#api.model does not have any list of recordset, so you can not loop through it.
You can easily achieve this by defining relational field.
class JournalEntries(models.Model):
_name = 'journal.entries'
journal_item = fields.Many2one('journal.item')
journal_id = fields.Many2one(comodel_name='erp.journal', related='journal_item.journal', string='Journal', readonly=True)
Click here to read about #api decorators

django-tables2: Adding columns/fields dynamically

I want to add a new field when somebody checks an option in my web page ("Add column 'external id' ")
table = IssueTable(issue_list)
show_ext = request.GET.get('show_ext', 0)
if show_ext:
table._meta.fields = table._meta.fields + ('external_id',)
I thought doing that it was the solution but I didn't succeed. The external_id is part of the model. table._meta.fields doesnt get updated and of course I cannot see the column in the table when this one is rendered.
class IssueTable(tables.Table):
def render_id(self, value, record):
if record.status.upper() in ['RESOLVED', 'INVALID']:
return mark_safe('<s>#%s</s>' % (reverse('issues.views.view', args=(record.pk,)), record.pk))
else:
return mark_safe('#%s' % (reverse('issues.views.view', args=(record.pk,)), record.pk))
def render_title(self, value, record):
return mark_safe('%s' % (reverse('issues.views.view', args=(record.id,)), value))
class Meta(object):
model = Issue
fields = ('id', 'title', 'product', 'type', 'priority', 'status', 'created')
attrs = {'class': 'table table-bordered'}
empty_text = _('No records found')
Any ideas?