null   1019

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orm - Unique fields that allow nulls in Django - Stack Overflow
class CharNullField(models.CharField):

"""
Subclass of the CharField that allows empty strings to be stored as NULL.
"""

description = "CharField that stores NULL but returns ''."

def from_db_value(self, value, expression, connection, contex):
"""
Gets value right out of the db and changes it if its ``None``.
"""
if value is None:
return ''
else:
return value


def to_python(self, value):
"""
Gets value right out of the db or an instance, and changes it if its ``None``.
"""
if isinstance(value, models.CharField):
# If an instance, just return the instance.
return value
if value is None:
# If db has NULL, convert it to ''.
return ''

# Otherwise, just return the value.
return value

def get_prep_value(self, value):
"""
Catches value right before sending to db.
"""
if value == '':
# If Django tries to save an empty string, send the db None (NULL).
return None
else:
# Otherwise, just pass the value.
return value
django  char  null  field  blank  text  string  db  sql  none  custom  orm 
6 days ago by christianmlong
Dealing with Nothing in C# - Nullable - DEV Community 👩‍💻👨‍💻
This is the English version of my original post in Hungarian. Photo by Unsplash...
null  nothing  value  c#  tutorial 
5 weeks ago by gilberto5757
tommy hueber tsm spectrum protect nul null device /dev/null
TSM and the bit bucket (/dev/null)
Posted on April 3, 2014
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In the past I’ve seen that people are asking for a TSM backup to /dev/null. It’s also a request on the ...
tommy  hueber  tsm  nul  null  device  /dev/null  from notes
july 2018 by theskett
First-Class Statistical Missing Values Support in Julia 0.7
about missing values in #julia gives a good overview of the “software engineer’s null” vs. the “data scientist’s null” and why it matters
julia  na  null  jennybc 
june 2018 by bikesandbooks

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