Re: TypeError: __str__ returned non-string (type bytes)

What happens when you throw in a print(obj.__dict__[field]) before the val assignment? You should see on the console what value each iteration of the loop is using and see if you have a strange attribute that is throwing things out of kilter.

-James

On Feb 24, 2015 8:33 PM, "Mike Dewhirst" <miked@dewhirst.com.au> wrote:

This is driving me insane so any hints will be greatly appreciated ...

Thanks

Mike

Here is the entire unedited test sequence plus failing code ...

Python:   3.4
Django:   1.6.9
SQLite3:  memory

Creating test database for alias 'default'...
.E.E...
======================================================================
ERROR: test_checkreference_exp (substance.tests.test_substance.TestSubstance)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Users\mike\env\xxdx3\ssds\substance\tests\test_substance.py", line 57, in test_checkreference_exp
    self.assertEqual(subst.checkreference('1'), True)
  File "C:\Users\mike\env\xxdx3\ssds\substance\models\substance.py", line 449, in checkreference
    if checkit(self, ref):
  File "C:\Users\mike\env\xxdx3\ssds\substance\models\substance.py", line 441, in checkit
    val = u"{0}".format(obj.__dict__[field])
TypeError: __str__ returned non-string (type bytes)

======================================================================
ERROR: testcheckreference_gas (substance.tests.test_substance.TestSubstance)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Users\mike\env\xxdx3\ssds\substance\tests\test_substance.py", line 75, in test_checkreference_gas
    self.assertEqual(subst.checkreference('1'.encode('utf-8')), True)
  File "C:\Users\mike\env\xxdx3\ssds\substance\models\substance.py", line 449, in checkreference
    if checkit(self, ref):
  File "C:\Users\mike\env\xxdx3\ssds\substance\models\substance.py", line 441, in checkit
    val = u"{0}".format(obj.__dict__[field])
TypeError: __str__ returned non-string (type bytes)

----------------------------------------------------------------------
Ran 7 tests in 1.281s

FAILED (errors=2)
Destroying test database for alias 'default'...

So here is the method in the substance model. The idea is that we check to see if the user included a bracketed reference in any field of substance or any field of a related object. I'll chop out the middle of the method to save space.

    def checkreference(self, ref):
        """Check all potential char fields for ref in square brackets eg [1]

        Give up as soon as it is found. Otherwise raise validation error.
        """
        def checkit(obj, ref):
            """Return True immediately but don't return False unless all
            fields have been checked."""
            for field in obj.__dict__:
                val = u"{0}".format(obj.__dict__[field])
                if ref in val:
                    return True

        assert(ref)
        ref = "[{0}]".format(ref)
        # first check self - the substance itself
        if checkit(self, ref):
            return True
        # now each of the 1:1 and 1:n objects
        try:
            obj = Solid.objects.get(substance=self)
            if checkit(obj, ref):
                return True
        except Solid.DoesNotExist:
            pass
<snip lots of similar try/except blocks>
        raise ValidationError("Reference {0} does not appear in any "
            "field".format(ref))

... and here is one of the tests (line 57 in the traceback) in error ...

    def test_checkreference_exp(self):
        subst = Substance.objects.get(name="Hazsub")
        exp, c = Explosive.objects.get_or_create(substance=subst)
        exp.compatibility = '[1]'
        exp.save()
        self.assertEqual(subst.checkreference('1'), True)



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