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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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Why escape_javascript before rendering a partial?
I'm looking at this Railscast episode and wondering why the call to escape_javascript is needed here:
4 Answers
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How to change options of with jQuery?
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You can remove the existing options by using the empty method, and then add your new options:
var option = $('<option></option>').attr("value", "option value").text("Text");
$("#selectId").empty().append(option);
If you have your new options in an object you can:
var newO...
Looping through the content of a file in Bash
... effects of trimming leading whitespace, interpreting backslash sequences, and skipping the last line if it's missing a terminating linefeed. If these are concerns, you can do:
while IFS="" read -r p || [ -n "$p" ]
do
printf '%s\n' "$p"
done < peptides.txt
Exceptionally, if the loop body m...
What does the “@” symbol mean in reference to lists in Haskell?
... = Tree a [Tree a], then t@(Tree _ kids) gives you access to both the tree and its children.
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Logging uncaught exceptions in Python
...d pointed out, sys.excepthook is invoked every time an exception is raised and uncaught. The practical implication of this is that in your code you can override the default behavior of sys.excepthook to do whatever you want (including using logging.exception).
As a straw man example:
>>> i...
Replace whole line containing a string using Sed
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You can use the change command to replace the entire line, and the -i flag to make the changes in-place. For example, using GNU sed:
sed -i '/TEXT_TO_BE_REPLACED/c\This line is removed by the admin.' /tmp/foo
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Rails create or update magic?
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Rails 6
Rails 6 added an upsert and upsert_all methods that deliver this functionality.
Model.upsert(column_name: value)
[upsert] It does not instantiate any models nor does it trigger Active Record callbacks or validations.
Rails 5, 4, and 3
Not ...
Gradle - getting the latest release version of a dependency
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Gradle currently does not support Maven's RELEASE (which is rarely used and deprecated) but it does support Ivy's latest.release. However, the general recommendation is to build against exact versions. Otherwise, the build can become a lottery.
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How do I convert a Vector of bytes (u8) to a string
I am trying to write simple TCP/IP client in Rust and I need to print out the buffer I got from the server.
3 Answers
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