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Validate uniqueness of multiple columns
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You can use validates to validate uniqueness on one column:
validates :user_id, uniqueness: {scope: :friend_id}
The syntax for the validation on multiple columns is similar, but you should provide an array of fields instead:
validates :attr, uniqueness: {scope: [:attr1...
A Java collection of value pairs? (tuples?)
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The Pair class is one of those "gimme" generics examples that is easy enough to write on your own. For example, off the top of my head:
public class Pair<L,R> {
private final L left;
private final R right;
public Pair(L left, R ...
Defining a percentage width for a LinearLayout? [duplicate]
...s 0.15, 0.70, 0.15. Then add your buttons to the second RelativeLayout(the one with weight 0.70).
Like this:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="fill_parent"
android:id="@+id/layoutContainer" an...
How do I get the directory that a program is running from?
...working directory. (Please don't suggest libraries unless they're standard ones like clib or STL.)
23 Answers
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Is there a cross-browser onload event when clicking the back button?
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Guys, I found that JQuery has only one effect: the page is reloaded when the back button is pressed. This has nothing to do with "ready".
How does this work? Well, JQuery adds an onunload event listener.
// http://code.jquery.com/jquery-latest.js
jQuery(wind...
Simplest PHP example for retrieving user_timeline with Twitter API version 1.1
...et twitter API tokens became a lot more bureaucratic. It has taken me over one working week to be provided a set of API tokens, and this is for an open source project for you guys and girls with over 1.2 million installations on Packagist and 1.6k stars on Github, which theoretically should be highe...
How to fix Git error: object file is empty?
...ery during a git operation. Boo.
I didn't have any backups. (N.B. Ubuntu One is not a backup solution for git; it will helpfully overwrite your sane repository with your corrupted one.)
To the git wizards, if this was a bad way to fix it, please leave a comment. It did, however, work for me... at...
Why would $_FILES be empty when uploading files to PHP?
... turned out that I had modified some of the PHP settings in .htaccess, and one of them (not sure which yet) was causing the upload to fail and $_FILES to be empty.
You could potentially try avoiding underscores (_) in the name="" attribute of the <input> tag
Try uploading very small files to n...
@import vs #import - iOS 7
...its headers and are touted as being safer and more efficient than #import.
One of the big advantages of using @import is that you don't need to add the framework in the project settings, it's done automatically. That means that you can skip the step where you click the plus button and search for the...
What is the difference D3 datum vs. data?
Can someone please explain the difference between datum() and data() in D3.js? I see both being used and I am not sure why you should choose one over the other?
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