Engineering diary
Problem: I have a data dump of a MongoDb query in a JSON file. I need to replace the ObjectID(“12345677abc”) with “12345677abc”.
Using Visual Studio Code’s find and replace
Find:
ObjectId\("([0-9a-fA-F]{24})"\)
Replace with: “$1”
Turns this
"_id" : ObjectId("5e3b1890e032d225a091d43f"),
"userId" : ObjectId("65ed1c2c-922c-4c82-b5bc-7324f69eea10"),To this
"_id" : "5e3b1890e032d225a091d43f",
"userId" : "65ed1c2c-922c-4c82-b5bc-7324f69eea10",
Bonus:
ISODate\("([^"]+)"\)A string 24 characters in length and only with hexadecimal letters and numbers
Example use: In MongoDb the unique id’s (ObjectId)
The string must be 24 characters long. ^ Starts of string or start of line, $ end of string or line; both dependent on the “multi-line mode”
/^{24}$/Hexadecimal uses only the letters “a to f” and the number “0 to 9”
/^[a-f0-9]{24}$/Okay in the previous post we had found the “find” tool and realised we can do so much more with it using regular expressions (regEx).
To recap a regEx is
“a sequence of symbols and characters expressing a string or pattern to be searched for within a longer piece of text.”
\d = a character 0 to 9
\w = any character a to Z and 0 to 9
\s = whitespace
Example:
\d\d\d will (using the find tool in your text editor) will highlight groups of 3 numbers in a string
\w\w\w\w\w will highlight groups of 5 characters
Notice how \w\w\w included numbers and letters
\s\s will highlight double spaces
A 4 letter word can be described as,
“a space followed by any 4 characters, followed by a space”
\s\w\w\w\w\s
Which can be rewritten as
\s\w{4}\s
But that will also include numbers. To ignore numbers
\s\w{4}[a-z]\s
Not quite there, if you are playing along you will notice that we are highlighting 4 letter words and the space before and after. What we need is to set boundaries.
\b\w{4}[a-z]\b
\b is a boundary, there are a few but for now lets stay with ‘spaces’. So with that you can find all four letter words