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how to permit an array with strong parameters
..., Date, Time, DateTime, StringIO, IO,
ActionDispatch::Http::UploadedFile and Rack::Test::UploadedFile.
To declare that the value in params must be an array of permitted scalar values map the key to an empty array:
params.permit(:id => [])
In my app, the category_ids are passed to the c...
How is the “greater than” or “>” character used in CSS?
... in CSS files but I have no idea how its used. Can anyone explain it to me and show how they are useful in making a page style easier?
...
How to read all files in a folder from Java?
... concern is efficiency, is it fast enough to be used for systems with thousands of files or is there a better alternative?
– Nitin Labhishetty
Mar 10 '14 at 15:28
17
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How to create a JavaScript callback for knowing when an image is loaded?
...
.complete + callback
This is a standards compliant method without extra dependencies, and waits no longer than necessary:
var img = document.querySelector('img')
function loaded() {
alert('loaded')
}
if (img.complete) {
loaded()
} else {
img.addEven...
How to change font size on part of the page in LaTeX?
... The first parameter to fontsize is the font size to switch to and the second is the line spacing to use
– Rose Perrone
Feb 20 '14 at 19:00
...
Is there auto type inferring in Java?
...whose scope is within the block where they have been defined. Similar to C and C++, but there is no auto or register keyword. However, the Java compiler will not allow the usage of a not-explicitly-initialized local variable and will give a compilation error (unlike C and C++ where the compiler will...
C++ inheritance - inaccessible base?
...
The default inheritance type of a class in C++ is private, so any public and protected members from the base class are limited to private. struct inheritance on the other hand is public by default.
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How to get the first column of a pandas DataFrame as a Series?
...
>>> import pandas as pd
>>> df = pd.DataFrame({'x' : [1, 2, 3, 4], 'y' : [4, 5, 6, 7]})
>>> df
x y
0 1 4
1 2 5
2 3 6
3 4 7
>>> s = df.ix[:,0]
>>> type(s)
<class 'pandas.core.series.Serie...
How to create duplicate allowed attributes
... AttributeUsage attribute onto your Attribute class (yep, that's mouthful) and set AllowMultiple to true:
[AttributeUsage(AttributeTargets.Method, AllowMultiple = true)]
public sealed class MyCustomAttribute: Attribute
sha...
NameError: name 'self' is not defined
...ot refer each other.
It's a common pattern to default an argument to None and add a test for that in code:
def p(self, b=None):
if b is None:
b = self.a
print b
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