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Django dynamic model fields
... equivalence
Something.objects.filter(data={'a': '1', 'b': '2'})
# subset by key/value mapping
Something.objects.filter(data__a='1')
# subset by list of keys
Something.objects.filter(data__has_keys=['a', 'b'])
# subset by single key
Something.objects.filter(data__has_key='a')
JSONField:
JS...
Can't subtract offset-naive and offset-aware datetimes
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UTC doesn't need a timezone, by definition. If the other datetime object is timezone aware then surely that provides the offset relative to UTC. UTC times may not have a timezone but they are not 'naive' and Python is handling this wrongly.
...
grepping using the “|” alternative operator
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By default, grep treats the typical special characters as normal characters unless they are escaped. So you could use the following:
grep 'gene\|exon' AT5G60410.gff
However, you can change its mode by using the following f...
Postgres unique constraint vs index
...ad some doubts about this basic but important issue, so I decided to learn by example.
Let's create test table master with two columns, con_id with unique constraint and ind_id indexed by unique index.
create table master (
con_id integer unique,
ind_id integer
);
create unique index maste...
Why is there a difference in checking null against a value in VB.NET and C#?
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VB.NET and C#.NET are different languages, built by different teams who have made different assumptions about usage; in this case the semantics of a NULL comparison.
My personal preference is for the VB.NET semantics, which in essence gives NULL the semantics "I don't know...
How do I decode HTML entities in Swift?
...gt;
becomes
4 < 5 & 3 > 2
On OS X there is CFXMLCreateStringByUnescapingEntities() which does the job:
let encoded = "<strong> 4 &lt; 5 &amp; 3 &gt; 2 .</strong> Price: 12 &#x20ac;. &#64; "
let decoded = CFXMLCreateStringByUnescapingEntities(nil, enco...
MySQL stored procedure vs function, which would I use when?
...y, or both. This means that a procedure can pass values back to the caller by using output parameters. These values can be accessed in statements that follow the CALL statement. Functions have only input parameters. As a result, although both procedures and functions can have parameters, procedure p...
How to inject dependencies into a self-instantiated object in Spring?
...ing manageable java class which had access to ApplicationContext. Inspired by scaffman.
Solved by:
AutowireCapableBeanFactory factory = applicationContext.getAutowireCapableBeanFactory();
factory.autowireBean(manuallyCreatedInstance);
...
INSERT … ON DUPLICATE KEY (do nothing)
...:
simple.
cons:
too slow.
auto-increment key will CHANGE(increase by 1) if there is entry matches unique key or primary key, because it deletes the old entry then insert new one.
2. INSERT IGNORE
pros:
simple.
cons:
auto-increment key will not change if there is entry matches uni...
Last non-empty cell in a column
... acknowledged that in a comment last night but put it in the original post by mistake. It does work in XL 2007 and 2010. Thanks.
– Doug Glancy
Mar 27 '11 at 16:41
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