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How to set default values in Rails?
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"Correct" is a dangerous word in Ruby. There's usually more than one way to do anything. If you know you'll always want that default value for that column on that table, setting them in a DB migration file is the easiest way:
class SetDefault < ActiveRecord::Migration
...
App Inventor 2 蓝牙遥控教程 - 经典蓝牙与BLE控制智能硬件 · App Inventor 2 中文网
... 7.3 常见问题与解决
问题 1：Error 908 ACCESS_FINE_LOCATION
问题 2：Android 12+ 扫描不到设备
问题 3：JDY-34 双模蓝牙模块连接问题
八、进阶技巧
8.1 使用滑动条控制速度
8.2 ...
Capture Image from Camera and Display in Activity
...ntents/result#kotlin
There are many built-in ActivityResultContracts that allow you to do different things like pick contacts, request permissions, take pictures or take videos. You are probably interested in the ActivityResultContracts.TakePicture shown above.
Note that androidx.fragment 1.3.0-al...
How to count the number of files in a directory using Python
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For all kind of files, subdirectories included:
import os
list = os.listdir(dir) # dir is your directory path
number_files = len(list)
print number_files
Only files (avoiding subdirectories):
import os
onlyfiles = next(os.w...
python design patterns [closed]
...for their existence.
It's nothing more than
class Null(object):
def __init__(self, *args, **kwargs):
"Ignore parameters."
return None
def __call__(self, *args, **kwargs):
"Ignore method calls."
return self
def __getattr__(self, mname):
"Ignore...
Find size of Git repository
...nt ideas of "complete size" you could use:
git bundle create tmp.bundle --all
du -sh tmp.bundle
Close (but not exact:)
git gc
du -sh .git/
With the latter, you would also be counting:
hooks
config (remotes, push branches, settings (whitespace, merge, aliases, user
details etc.)
stashes (see ...
Java “lambda expressions not supported at this language level”
...: android { compileOptions { sourceCompatibility JavaVersion.VERSION_1_8 targetCompatibility JavaVersion.VERSION_1_8 } }
– BaDo
Sep 25 '15 at 2:30
...
How to Unit test with different settings in Django?
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EDIT: This answer applies if you want to change settings for a small number of specific tests.
Since Django 1.4, there are ways to override settings during tests:
https://docs.djangoproject.com/en/dev/topics/testing/tools/#overriding-settings
TestCase will have a self.settings context ma...
Determine what attributes were changed in Rails after_save callback?
I'm setting up an after_save callback in my model observer to send a notification only if the model's published attribute was changed from false to true. Since methods such as changed? are only useful before the model is saved, the way I'm currently (and unsuccessfully) trying to do so is as fol...
How to set radio button checked as default in radiogroup?
I have created RadioGroup and RadioButton dynamically as following:
8 Answers
8
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