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How to change a nullable column to not nullable in a Rails migration?
I created a date column in a previous migration and set it to be nullable. Now I want to change it to be not nullable. How do I go about doing this assuming there are null rows in that database? I'm ok with setting those columns to Time.now if they're currently null.
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How to install the Raspberry Pi cross compiler on my Linux host machine?
...arm-linux-gnueabihf-raspbian/bin
to the end of the file named ~/.bashrc
Now you can either log out and log back in (i.e. restart your terminal session), or run . ~/.bashrc in your terminal to pick up the PATH addition in your current terminal session.
Now, verify that you can access the compiler...
What are Aggregates and PODs and how/why are they special?
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How to read:
This article is rather long. If you want to know about both aggregates and PODs (Plain Old Data) take time and read it. If you are interested just in aggregates, read only the first part. If you are interested only in PODs then you must first read the definition, implic...
How to create GUID / UUID?
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UUIDs (Universally Unique IDentifier), also known as GUIDs (Globally Unique IDentifier), according to RFC 4122, are identifiers designed to provide certain uniqueness guarantees.
While it is possible to implement an RFC-compliant UUIDs in a few lines of JS (E.g. see @b...
Check if a string contains a string in C++
...proach" << std::endl;
start = high_resolution_clock::now();
for(size_t i=0; i<haystacksCount; ++i)
{
if(haystacks[i].find(needle) != std::string::npos)
{
sink = !s...
Programmatically add custom event in the iPhone Calendar
...te the event handling inside of a block.
2) You need to commit your event now or pass the "commit" param to your save/remove call
Everything else stays the same...
Add the EventKit framework and #import <EventKit/EventKit.h> to your code.
In my example, I have a NSString *savedEventId inst...
ANTLR: Is there a simple example?
...message, and the files ExpLexer.java, ExpParser.java and Exp.tokens should now be generated.
To see if it all works properly, create this test class:
import org.antlr.runtime.*;
public class ANTLRDemo {
public static void main(String[] args) throws Exception {
ANTLRStringStream in = n...
How to get an array of unique values from an array containing duplicates in JavaScript? [duplicate]
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It's 2014 now, so we need semicolons again.
– tacone
Jan 8 '14 at 17:35
56
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Getting the first and last day of a month, using a given DateTime object
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I know I'm being picky here, but shouldn't lastDayofMonth be firstDayOfMonth.AddMonths(1).AddSeconds(-1);?
– Karl Gjertsen
Jan 5 '16 at 15:27
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How to generate unique ID with node.js
...(); // -> '110ec58a-a0f2-4ac4-8393-c866d813b8d1'
** UPDATE 7.x
And now the above usage is deprecated as well, so use this package like this:
const { v1: uuidv1 } = require('uuid');
uuidv1(); // -> '6c84fb90-12c4-11e1-840d-7b25c5ee775a'
const { v4: uuidv4 } = require('uuid');
uuidv4()...