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How to change a nullable column to not nullable in a Rails migration?
...s:
# Make sure no null value exist
MyModel.where(date_column: nil).update_all(date_column: Time.now)
# Change the column to not allow null
change_column :my_models, :date_column, :datetime, null: false
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Websocket API to replace REST API?
... and collections can be passed around from/to client and server by simply calling a functions RPC-style. No more managing REST endpoints, serializing/deserializing objects, and so forth. I haven't worked with socketstream yet, but it looks worth checking out.
I still have a long way to go before I ...
Xcode “The private key for is not installed on this mac - distributing”
...list of signing identities.
Go back to the developer website and make sure all your provisioning profiles are configured with the new certificate. (They should all be listed as Active when you are done.)
Go back to XCode and refresh your list of provisioning profiles.
I had the same issue as you d...
Can I safely delete contents of Xcode Derived data folder?
...
Yes, you can delete all files from DerivedData sub-folder (Not DerivedData Folder) directly.
That will not affect your project work. Contents of DerivedData folder is generated during the build time and you can delete them if you want. It's no...
How can I make PHP display the error instead of giving me 500 Internal Server Error [duplicate]
This has never happened before. Usually it displays the error, but now it just gives me a 500 internal server error. Of course before, when it displayed the error, it was different servers. Now I'm on a new server (I have full root, so if I need to configure it somewhere in the php.ini, I can.) Or p...
Algorithm to return all combinations of k elements from n
... set it's best to use a modified gray code algorithm so you aren't holding all of them in memory. These generate the next combination from the previous and avoid repetitions. There are many of these for different uses. Do we want to maximize the differences between successive combinations? minimize?...
How to design a database for User Defined Fields?
...rformance is the primary concern, I would go with #6... a table per UDF (really, this is a variant of #2). This answer is specifically tailored to this situation and the description of the data distribution and access patterns described.
Pros:
Because you indicate that some UDFs
have values for a...
What is a Context Free Grammar?
...y and then the Wikipedia entry on formal grammar, I am left utterly and totally befuddled. Would someone be so kind as to explain what these things are?
...
How to create separate AngularJS controller files?
I have all of my AngularJS controllers in one file, controllers.js. This file is structured as follows:
6 Answers
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What's the best strategy for unit-testing database-driven applications?
...ns that are driven by databases of varying complexity on the backend. Typically, there's an ORM layer separate from the business and presentation logic. This makes unit-testing the business logic fairly straightforward; things can be implemented in discrete modules and any data needed for the test...