MongoDb doesn't support keys with dot. I have a Ruby nested hash that has many keys with dot (.) character. Is there a configuration that can be used to specify a character replacement for . like an underscore _ while inserting such data to MongoDb
I'm using MongoDB with Ruby & mongo gem.
example hash is like below
{
"key.1" => {
"second.key" => {
"third.key" => "val"
}
}
}
If it isn't possible to use keys with . in Mongodb, you'll have to modify the input data :
hash = {
'key.1' => {
'second.key' => {
'third.key' => 'val.1',
'fourth.key' => ['val.1', 'val.2']
}
}
}
This recursive method transforms the keys of a nested Hash :
def nested_gsub(object, pattern = '.', replace = '_')
if object.is_a? Hash
object.map do |k, v|
[k.to_s.gsub(pattern, replace), nested_gsub(v, pattern, replace)]
end.to_h
else
object
end
end
nested_gsub(hash) returns :
{
"key_1" => {
"second_key" => {
"third_key" => "val.1",
"fourth_key" => [
"val.1",
"val.2"
]
}
}
}
It's possible to add more cases to the previous method :
def nested_gsub(object, pattern = '.', replace = '_')
case object
when Hash
object.map do |k, v|
[k.to_s.gsub(pattern, replace), nested_gsub(v, pattern, replace)]
end.to_h
when Array
object.map { |v| nested_gsub(v, pattern, replace) }
when String
object.gsub(pattern, replace)
else
object
end
end
nested_gsub will now iterate on string values and arrays :
{
"key_1" => {
"second_key" => {
"third_key" => "val_1",
"fourth_key" => [
"val_1",
"val_2"
]
}
}
}
In mongoDB, there is no configuration to support dot in the key. You need to preprocess the JSON before inserting to MongoDB collection.
One approach is that you can replace the dot with its unicode equivalent U+FF0E before insertion.
Hope this helps.