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A migration to add unique constraint to a combination of columns
... unique: true
Trying to create two similar records will throw a database error (Postgres in my case):
ActiveRecord::RecordNotUnique: PG::UniqueViolation: ERROR: duplicate key value violates unique constraint "index_ownerships_on_user_id_and_post_id"
DETAIL: Key (user_id, post_id)=(1, 1) already...
SLF4J: Failed to load class “org.slf4j.impl.StaticLoggerBinder”
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Yes, the error goes as also mentioned here - slf4j.org/manual.html But i get a new error now - Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory
– david blaine
Ap...
Is it better to use C void arguments “void foo(void)” or not “void foo()”? [duplicate]
...e. If the caller calls the function and gives it some argument, that is an error and the compiler spits out an appropriate error.
The second way of declaring a function has plenty of benefits. One of course is that amount and types of parameters are checked. Another difference is that because the ...
Advantages of Antlr (versus say, lex/yacc/bison) [closed]
...nstruct and debug. The downside is you have to deal with somewhat cryptic errors like shift-reduce and (the dreaded) reduce-reduce. These are errors that Bison catches when generating the parser, so it doesn't affect the end-user experience, but it can make the development process a bit more inter...
When to use an assertion and when to use an exception
...The comment about the hard drive is wrong. Assertions are for checking for errors in your code logic. Never, ever, use them to check something that you don't control. Remember, if an assertion fails it means that your code is wrong.
– Ian Goldby
Nov 14 '13 at 1...
How to save and load cookies using Python + Selenium WebDriver
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I'm getting "pickle protocol must be <= 2" error. Using the pickle code you posted. What does this mean? Is it referring to the arguments?
– Aaron Hiniker
Feb 25 '13 at 0:50
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Rename a class in Xcode: Refactor… is grayed out (disabled). Why?
...ame" in latest xcode and it failed - again!
(this time with the incorrect error: "Unable to determine the language of", one of those error messages where Apple put the wrong text in place)
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How to create a database from shell command?
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I get this error ERROR 1046 (3D000) at line 27: No database selected when I run echo "create database databasename" | mysql -u -u username -p command
– keerthi
Mar 15 '13 at 5:16
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How do I combine a background-image and CSS3 gradient on the same element?
How do I use CSS3 gradients for my background-color and then apply a background-image to apply some sort of light transparent texture?
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How can I fix WebStorm warning “Unresolved function or method” for “require” (Firefox Add-on SDK)
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I still have the error in the compiler error TS2304: Cannot find name 'require'.
– SuperUberDuper
Oct 21 '16 at 12:12
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