When I want to check if a value from an HTML form equals to a value from the database (which it does) it returns false instead of true.
Do I need more code?
Code:
password = params[:password]
password_db = #db.execute('SELECT password FROM dtbs WHERE username=?', [params[:username]])
puts password #returns llol123
puts password_db #returns llol123
check = (password==password_db)
puts check #returns false
I'm guessing the return type of the password_db is in an array or something? Try getting the type of the values
puts password.class
puts password_db.class
I'm guessing they are different.
Using (password_db[0]==password) returns true.
That's the best way.
I am new to rails. What I see that there are a lot of ways to find a record:
find_by_<columnname>(<columnvalue>)
find(:first, :conditions => { <columnname> => <columnvalue> }
where(<columnname> => <columnvalue>).first
And it looks like all of them end up generating exactly the same SQL. Also, I believe the same is true for finding multiple records:
find_all_by_<columnname>(<columnvalue>)
find(:all, :conditions => { <columnname> => <columnvalue> }
where(<columnname> => <columnvalue>)
Is there a rule of thumb or recommendation on which one to use?
where returns ActiveRecord::Relation
Now take a look at find_by implementation:
def find_by
where(*args).take
end
As you can see find_by is the same as where but it returns only one record. This method should be used for getting 1 record and where should be used for getting all records with some conditions.
Edit:
This answer is very old and other, better answers have come up since this post was made. I'd advise looking at the one posted below by #Hossam Khamis for more details.
Use whichever one you feel suits your needs best.
The find method is usually used to retrieve a row by ID:
Model.find(1)
It's worth noting that find will throw an exception if the item is not found by the attribute that you supply. Use where (as described below, which will return an empty array if the attribute is not found) to avoid an exception being thrown.
Other uses of find are usually replaced with things like this:
Model.all
Model.first
find_by is used as a helper when you're searching for information within a column, and it maps to such with naming conventions. For instance, if you have a column named name in your database, you'd use the following syntax:
Model.find_by(name: "Bob")
.where is more of a catch all that lets you use a bit more complex logic for when the conventional helpers won't do, and it returns an array of items that match your conditions (or an empty array otherwise).
Model.find
1- Parameter: ID of the object to find.
2- If found: It returns the object (One object only).
3- If not found: raises an ActiveRecord::RecordNotFound exception.
Model.find_by
1- Parameter: key/value
Example:
User.find_by name: 'John', email: 'john#doe.com'
2- If found: It returns the object.
3- If not found: returns nil.
Note: If you want it to raise ActiveRecord::RecordNotFound use find_by!
Model.where
1- Parameter: same as find_by
2- If found: It returns ActiveRecord::Relation containing one or more records matching the parameters.
3- If not found: It return an Empty ActiveRecord::Relation.
There is a difference between find and find_by in that find will return an error if not found, whereas find_by will return null.
Sometimes it is easier to read if you have a method like find_by email: "haha", as opposed to .where(email: some_params).first.
Since Rails 4 you can do:
User.find_by(name: 'Bob')
which is the equivalent find_by_name in Rails 3.
Use #where when #find and #find_by are not enough.
The accepted answer generally covers it all, but I'd like to add something,
just incase you are planning to work with the model in a way like updating, and you are retrieving a single record(whose id you do not know), Then find_by is the way to go, because it retrieves the record and does not put it in an array
irb(main):037:0> #kit = Kit.find_by(number: "3456")
Kit Load (0.9ms) SELECT "kits".* FROM "kits" WHERE "kits"."number" =
'3456' LIMIT 1
=> #<Kit id: 1, number: "3456", created_at: "2015-05-12 06:10:56",
updated_at: "2015-05-12 06:10:56", job_id: nil>
irb(main):038:0> #kit.update(job_id: 2)
(0.2ms) BEGIN Kit Exists (0.4ms) SELECT 1 AS one FROM "kits" WHERE
("kits"."number" = '3456' AND "kits"."id" != 1) LIMIT 1 SQL (0.5ms)
UPDATE "kits" SET "job_id" = $1, "updated_at" = $2 WHERE "kits"."id" =
1 [["job_id", 2], ["updated_at", Tue, 12 May 2015 07:16:58 UTC +00:00]]
(0.6ms) COMMIT => true
but if you use where then you can not update it directly
irb(main):039:0> #kit = Kit.where(number: "3456")
Kit Load (1.2ms) SELECT "kits".* FROM "kits" WHERE "kits"."number" =
'3456' => #<ActiveRecord::Relation [#<Kit id: 1, number: "3456",
created_at: "2015-05-12 06:10:56", updated_at: "2015-05-12 07:16:58",
job_id: 2>]>
irb(main):040:0> #kit.update(job_id: 3)
ArgumentError: wrong number of arguments (1 for 2)
in such a case you would have to specify it like this
irb(main):043:0> #kit[0].update(job_id: 3)
(0.2ms) BEGIN Kit Exists (0.6ms) SELECT 1 AS one FROM "kits" WHERE
("kits"."number" = '3456' AND "kits"."id" != 1) LIMIT 1 SQL (0.6ms)
UPDATE "kits" SET "job_id" = $1, "updated_at" = $2 WHERE "kits"."id" = 1
[["job_id", 3], ["updated_at", Tue, 12 May 2015 07:28:04 UTC +00:00]]
(0.5ms) COMMIT => true
Apart from accepted answer, following is also valid
Model.find() can accept array of ids, and will return all records which matches.
Model.find_by_id(123) also accept array but will only process first id value present in array
Model.find([1,2,3])
Model.find_by_id([1,2,3])
The answers given so far are all OK.
However, one interesting difference is that Model.find searches by id; if found, it returns a Model object (just a single record) but throws an ActiveRecord::RecordNotFound otherwise.
Model.find_by is very similar to Model.find and lets you search any column or group of columns in your database but it returns nil if no record matches the search.
Model.where on the other hand returns a Model::ActiveRecord_Relation object which is just like an array containing all the records that match the search. If no record was found, it returns an empty Model::ActiveRecord_Relation object.
I hope these would help you in deciding which to use at any point in time.
Suppose I have a model User
User.find(id)
Returns a row where primary key = id. The return type will be User object.
User.find_by(email:"abc#xyz.com")
Returns first row with matching attribute or email in this case. Return type will be User object again.
Note :- User.find_by(email: "abc#xyz.com") is similar to User.find_by_email("abc#xyz.com")
User.where(project_id:1)
Returns all users in users table where attribute matches.
Here return type will be ActiveRecord::Relation object. ActiveRecord::Relation class includes Ruby's Enumerable module so you can use it's object like an array and traverse on it.
Both #2s in your lists are being deprecated. You can still use find(params[:id]) though.
Generally, where() works in most situations.
Here's a great post: https://web.archive.org/web/20150206131559/http://m.onkey.org/active-record-query-interface
The best part of working with any open source technology is that you can inspect length and breadth of it.
Checkout this link
find_by ~> Finds the first record matching the specified conditions. There is no implied ordering so if order matters, you should specify it yourself. If no record is found, returns nil.
find ~> Finds the first record matching the specified conditions , but if no record is found, it raises an exception but that is done deliberately.
Do checkout the above link, it has all the explanation and use cases for the following two functions.
I will personally recommend using
where(< columnname> => < columnvalue>)
I have an array, "templates".
puts templates
gives me the following output:
{"id"=>4, "subject"=>"invoice", "body"=>"dear sirs", "description"=>"banking", "groups"=>"123", 0=>4, 1=>"invoice", 2=>"dear sirs", 3=>"banking", 4=>"123"}
I would like to "put" a certain element e.g. "dear sirs". I have tried:
puts templates[2]
but this just returns nil. What is the correct way to do this?
You access "dear sirs" using the key that's associated with it, "body":
puts templates["body"]
Suppose if you have hash like this
#a = {"id"=>4, "subject"=>"invoice", "body"=>"dear sirs", "description"=>"banking", "groups"=>"123", 0=>4, 1=>"invoice", 2=>"dear sirs", 3=>"banking", 4=>"123"}
And if you want to get value of key name 'body', then you can get output like this,
puts #a['body'] //Output = dear sirs
puts #a['subject'] //Output = invoice
For more information for ruby hash Ruby Hash
If you want to get a hash value by numeric index then you can do templates.values[index]
e.g
templates.values[0] => 4
templates.values[1] => "invoice"
templates.values[2] => "dear sirs"
Note: My answer is based on strong assumptions that may not be true. I have provided steps to validate that.
In-case you are on older ruby version you need to do puts templates.inspect in-order to print a Hash. Therefore suggesting your variable templates is a String. Best way to verify:
templates.class
#=> returns Hash or String accordingly.
If it return String, you can proceed as follows:
Convert the String into Hash
hash = eval(templates)
#=> {"subject"=>"invoice", 0=>4, "description"=>"banking", 1=>"invoice", 2=>"dear sirs", "id"=>4, 3=>"banking", "body"=>"dear sirs", 4=>"123", "groups"=>"123"}
Now that its a Hash you can access any value using its key like:
hash[key]
#=> val
Example for your case:
hash[2]
#=> "dear sirs"
I have a form that displays inputs based on user preferences. I am storing the values as an hstore hash since I dont know ahead of time exactly what the form input for each user will be. The problem I am running in to is that even though a user has an input preferenced doesnt mean they have to enter a value for it each time. Which, can result in :foo => "".
All the doc examples show you how to find records you know the key name of. In my case, I dont know the key name...I need to find all the keys in a hash whose value => "".
Then, I should be able to do something like the docs shows...for each empty value
person.destroy_key(:data, :foo).destroy_key(:data, :bar).save
avals(hstore) is likely what I need to user... How do you use avals with rails?
Since hstore is just a hash in rails...you just need to evaluate the hash before saving it.
...in model
before_save :remove_blanks
private
def remove_blanks
self.hstore = self.hstore.reject{ |k,v| v.blank? }
end
replace 'hstore' with your hstore column name
Any of you guys know how to query rally for a set of things where an string attribute value is currently not yet set?
I can’t query for the value equal to an empty string. That doesn’t parse. And I can’t use “null” either. Or rather, I can try “null” and it parses fine but it doesn’t result in finding anything.
query = #rally_api.find(:defect, :fetch =>true,
:project_scope_up => false, :project_scope_down => false,
:workspace => #workspace,
:project => #project) { equals :integration_i_d, "" }
This was followed up by telling the me to substitute "" with nil which didn't work. Null was tried to no success as well. I've tried "null" and null and "". None of them work.
I'm not familiar with our Ruby REST toolkit but directly hitting our WSAPI, you would say (<Field> = null). Notice that there are no quotes around "null".
Also, I'm wondering if the use of contains in your example above is what you wanted. You might want =.
try: { equal :integration_i_d, '""' }
Also, if rally_rest_api seems slow - we're working on something faster here:
http://developer.rallydev.com/help/ruby-rally-api