大约有 40,000 项符合查询结果（耗时：0.0519秒） [XML]
Unique BooleanField value in Django?
... save method of the model and if you've set the boolean to True, make sure all others are set to False.
from django.db import transaction
class Character(models.Model):
name = models.CharField(max_length=255)
is_the_chosen_one = models.BooleanField()
def save(self, *args, **kwargs):
...
Why would you use Expression rather than Func?
...y. Ie. you need database.data.Where(i => i.Id > 0) to be executed as SELECT FROM [data] WHERE [id] > 0. If you just pass in a Func, you've put blinders on your driver and all it can do is SELECT * and then once it's loaded all of that data into memory, iterate through each and filter out ev...
Increasing (or decreasing) the memory available to R processes
...program
icon (the icon on your desktop or in
your programs directory). Select
``Properties'', and then select the
``Shortcut'' tab. Look for the
``Target'' field and after the closing
quotes around the location of the R
executible, add
--max-mem-size=500M
as shown in the fig...
Draw text in OpenGL ES
I'm currently developing a small OpenGL game for the Android platform and I wonder if there's an easy way to render text on top of the rendered frame (like a HUD with the player´s score etc). The text would need to use a custom font also.
...
'0000-00-00 00:00:00' can not be represented as java.sql.Timestamp error
...o update the values, or while these modifications take place, you can do a select using a case/when.
SELECT CASE ModificationDate WHEN '0000-00-00 00:00:00' THEN '1970-01-01 01:00:00' ELSE ModificationDate END AS ModificationDate FROM Project WHERE projectId=1;
...
FTP/SFTP access to an Amazon S3 Bucket [closed]
...also modifying the objects in the bucket. The value "30" in my system was selected somewhat arbitrarily.
-o enable_noobj_cache (default is disable)
enable cache entries for the object which does not exist. s3fs always has to check whether file(or sub directory) exists under object(path) when s3fs...
Reference — What does this symbol mean in PHP?
... have the same results.
Pre-increment is a little bit faster because it really increments the variable and after that 'returns' the result. Post-increment creates a special variable, copies there the value of the first variable and only after the first variable is used, replaces its value with seco...
How to know if an object has an attribute in Python
...n is that, if the property is likely to be there most of the time, simply call it and either let the exception propagate, or trap it with a try/except block. This will likely be faster than hasattr. If the property is likely to not be there most of the time, or you're not sure, using hasattr will pr...
Cannot serve WCF services in IIS on Windows 8
...r's (see above). From the Server Manager, click on Add roles and features, select the appropriate server, then select Features. Under .NET Framework 4.5 Features, you'll see WCF Services, and under that, you'll find HTTP Activation.
...
How to properly reuse connection to Mongodb across NodeJs application and modules
...lhost:27017";
var _db;
module.exports = {
connectToServer: function( callback ) {
MongoClient.connect( url, { useNewUrlParser: true }, function( err, client ) {
_db = client.db('test_db');
return callback( err );
} );
},
getDb: function() {
return _db;
}
};
To...