大约有 47,000 项符合查询结果（耗时：0.0927秒） [XML]
Difference between Django's annotate and aggregate methods?
...
I would focus on the example queries rather than your quote from the documentation. Aggregate calculates values for the entire queryset. Annotate calculates summary values for each item in the queryset.
Aggregation
>>> Book.objects.aggregate(average_price=Avg('price'))
{'av...
java.lang.IllegalStateException: Cannot (forward | sendRedirect | create session) after response has
... the output stream after you have tried to do the forward. If it is coming from the above line, then it means that somewhere before this line you have either:
output data to the output stream, or
done another redirect beforehand.
Good luck!
...
How does Rails keep track of which migrations have run for a database?
.... If you roll back that migration, Rails will delete the corresponding row from schema_migrations.
For example, running a migration file named 20120620193144_create_users.rb will insert a new row with a version of 20120620193144 into the schema_migrations table.
You are free at any point to introd...
How to take emulator screenshots using Eclipse?
...ed to use the Other... submenu and dialog, as Devices is also the 4th item from the top in the Show View submenu.
– mklement0
Sep 7 '13 at 15:29
1
...
Filter output in logcat by tagname
I'm trying to filter logcat output from a real device (not an emulator) by tag name but I get all the messages which is quite a spam. I just want to read messages from browser which should be something like "browser: " or "webkit: " , but it doesn't work...
Here it is what I get:
...
Adding two Java 8 streams, or an extra element to a stream
...bout the concat operation.
In it they discuss the issues that could arise from those cases in which the stream could be infinite and what concatenation would mean in those cases, but I do not think that was the reason for the modification.
You see in this other thread that some early users of the ...
What is this weird colon-member (“ : ”) syntax in the constructor?
... the exceptions listed at the end of the FAQ entry).
The takeaway point from the FAQ entry is that,
All other things being equal, your code will run faster if you use initialization lists rather than assignment.
sha...
Is git not case sensitive?
...
looks like this was right (except that I was changing from capital letters to downcase)
– JAkk
Dec 12 '11 at 22:30
...
pretty-print JSON using JavaScript
...is great if you have an object you want pretty printed. If you're starting from a valid JSON string that you want to pretty printed, you need to convert it to an object first:
var jsonString = '{"some":"json"}';
var jsonPretty = JSON.stringify(JSON.parse(jsonString),null,2);
This builds a JSON ...
How can I get sin, cos, and tan to use degrees instead of radians?
...
Multiply the input by Math.PI/180 to convert from degrees to radians before calling the system trig functions.
You could also define your own functions:
function sinDegrees(angleDegrees) {
return Math.sin(angleDegrees*Math.PI/180);
};
and so on.
...