Just simple check with ruby driver if record exist in database.
Like
Main = db.collection(main)
Record = main.find("record" => name)
If record?
Puts record exist
Else
Dont exist
End
This doesnt work can someone tell me how to do it
The following will put true or false whether the record exists
puts main.record.where(record: name).exists?
This can be done with the collection method "find" as you did, but the selector must be a hash.
col = db.collection(main)
record = col.find({:property => value})
Find also accepts an optional hash of options.
Take a look at the documentation. http://api.mongodb.org/ruby/current/Mongo/Collection.html#find-instance_method
Related
I use ruby-2.3 and oci-8 gem. I want to make the select query:
stm = "select * from DATASERVICEUSERS t where boss<>100 and loginad is not null"
res = CONN.exec(stm).fetch_hash do |row|
#do something with row
end
CONN.logoff
How can I query the result of the whole to put for example in an array or hash, instead of cycle pass through each record? I need just a collection of elements of the result of this request.
Oci-8 doesn't provice that. The .exec method produces a cursor that you you need to process like your code demonstrates. You can fill up an array with an array of fields or a hash.
Here an example for an array
records = []
conn.exec(sql) { |record| records << record}
# records: [["xxxx", "xxxx"], ["yyyy", "yyyy"], ..]
I know this is quite an old question but I've come across this problem. I'm not as well versed in ruby but oci8 2.2.7 actually provides fetch_hash
https://www.rubydoc.info/gems/ruby-oci8/OCI8/Cursor#fetch_hash-instance_method
here's an example from my use case:
records = []
dataCursor = #odb.exec(queryUUNRData)
while((data = dataCursor.fetch_hash) != nil)
records.push data
end
dataCursor.close
the resulting dataset already includes the column names as hash key
I'm using Mongoid to access a MongoDB database, however I'm running into an odd problem. It seems like I can only query for records using find_by, as find will always return nil:
invoices = Invoice.find({})
p "invoices"
p invoices
puts ''
invoice = Invoice.find_by({ _id: <ObjectId> })
p "invoice"
p invoice
puts ''
The second query using find_by will return a single record. According to the documentation, find should be returning every record that satisfies the query.
Does anyone have an idea what could be causing this?
Be careful not to confuse the Moped syntax with the Mongoid syntax. For Mongoid, the docs describe the find method:
Find a document or multiple documents by their ids. Will raise an error by default if any of the ids do not match
If you really want every record, Invoice.all can do the trick. (Also be careful with your find_by method. The Mongoid syntax varies from mongo's a bit, so you don't have to have the curlies around your params.)
I am using Sinatra and Sequel with PostgreSQL.
After authentication, I want to welcome the user by printing their name but I cannot get only the value of the user's name from the database, it comes out as a hash.
The query is:
current_user = DB[:users].select(:username).where('password = ?', password).first
and the resulting piece of data is:
Welcome, {:username=>"Rich"}
which looks rather weird, I would prefer it to read "Welcome, Rich".
What am I doing wrong here? I tried the same query without 'first" at the end and that does not work either.
You can either pull the (single) column you selected out of the Hash you are given:
current_user = DB[:users].select(:username).where('password=?', password).first[:username]
Or you can map your results to an array of usernames and pull the first:
# Using a hash in the filter method is simpler than SQL placeholders.
current_user = DB[:users].filter(password:password).select_map(:username).first
But the best way is to get only the user you care about, and then get the name:
# Using [] on a dataset returns the first row matching the criteria
current_user = DB[:users][password:password][:username]
Try Sequel::Dataset#get. Also, as Phrogz points out, Sequel::Dataset#where can take a hash (it will securely escape values to prevent injection attacks).
current_username = DB[:users].where(password: password).get(:username)
There's also Sequel::Dataset#where_single_value, which is optimized for this exact situation:
current_username = DB[:users].select(:username).where_single_value(password: password)
I'm using the following with datamapper to create/get a new user from my db:
user = User.first_or_create({:id => data['id']})
This gets the user with id = data['id'] or creates it if it doesn't already exist.
I want to know how to set other attributes/fields of the returned object regardless of whether it is a new record or existing?
Is the only way to do this to then call user.update({:field => value ...}) or is there a better way to achieve this?
Well, you could write it as one line:
(User.first_or_create(:id => data['id'])).update(:field => value)
with hashes for the parameters if you wish (or if you need to specify more than one); however, it's worth noting that this will only work if the model as specified by the first_or_create is valid. If :name were a required field, for instance, then this wouldn't work:
(User.first_or_create({:id => data['id'], :name => "Morse"})).update(:name => "Lewis")
as the creation in the first part would fail.
You could get around this by specifying the parameters needed for a new record with something like
(User.first_or_create({:id => data['id'], :name => "Morse"}, {:name => "Lewis"})).update(:name => "Lewis")
but this is unusually painful, and is difficult to read.
Also note that using first_or_create with an :id will attempt to create a model with that specific :id, if such a record doesn't exist. This might not be what you want.
Alternatively, you can use first_or_new. You can't call update on an object created using this, however, as the record won't exist (although I believe this might have worked in previous versions of DataMapper).
Just for anyone coming across this answer, User.first_or_create({:id => data['id']}) does NOT "get the user with id = data['id'] or creates it if it doesn't already exist." It actually gets the first record in the table and changes its id t0 data['id'].
To actually get the first record with that id, or create it if it doesn't exist, you need to use a where clause:
User.where(id: data['id]).first_or_create
I have records with a 'resource' field which can contain multiple resources. When I return this data, I need to iterate over this field and return an individual record for each value in the field. I am currently using sinatra and am able to interate over the fields okay, but I am having difficulty replacing the field in the json array.
For example
event: Name
resources: resourceA, resourceB, resourceC
This record needs to be returned as 3 uniqe records/events with only one resource per record.
With the code listed below, I am getting three records, but all three records are coming back with the same resource value (resourceC)
Here is my code
docs = #db.view('lab/events', :startkey => params[:startDate], :endkey => endSearch)['rows']
rows = Array.new
docs.each do |doc|
resources = doc['value']['resources'].split(",")
resources.each do |r|
doc['value']['resources'] = r
rows.push(doc['value'])
end
end
Any help is greatly appreciated.
Thanks
Chris
if you use the ruby gem "json" you can convert the json string to a hash
require 'json'
converted_hash = JSON(json_string).to_hash
This should be much easier to manage.
You can then turn the hash to a JSON string:
new_json_string = converted_hash.to_json
Basically what is happening is ruby is seeing all three records as the same record so as the hash value is updated on one record, it impacts all other records that were created from the same doc. To get around this, I acutally needed to create a duplicate record each time through and modify it's value.
docs = #db.view('lab/events', :startkey => params[:startDate], :endkey => endSearch)['rows']
rows = Array.new
docs.each do |doc|
resources = doc['value']['resources'].split(",")
resources.each do |r|
newDoc = doc['value'].dup # <= create a duplicate record and update the value
newDoc["resources"] = r
rows.push(newDoc)
end
end