I am using gem rails~> 5.2 and gem mysql2 >= 0.3.13, < 0.5.
I have a model Lawer, which has an array column lawer_filed [sic].
# Model lawer.rb
serialize :lawer_field, Array
Then I created a Lawer, and I can get the lawer_field value as follows:
=> Lawer.first.lawer_field
=> ["2", "3", "5"]
Now, I want to find one Lawer with a query using lawer_field. I tried:
#lawer = Lawer.where("lawer_field && ARRAY[?]", "2")
which raised an error like this:
ActiveRecord::StatementInvalid (Mysql2::Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '['2']) LIMIT 11' at line 1: SELECT `lawers`.* FROM `lawers` WHERE (lawer_field && ARRAY['2']) LIMIT 11)
There is a mistake in my SQL syntax, but I don't how to fix it. Can anyone help?
MySQL, unlike PostgreSQL, does not support arrays in database. Therefore you needed to add this line:
serialize :lawer_field, Array
This means that you have a string field in your database, but whenever ActiveRecord is unpacking results returned by the database, it maps them directly to an instance of Ruby Array. What this means is that your only option to filter the results in the database is with any MySQL string comparison functions, LIKE, etc.
Your options are to either use LIKE or perform some other String functions (which will not perform well as you will be unable to use indices) or build another table, add a has_many association to it and use MySQL the way it was supposed to be used. You could also, of course, migrate to PostgreSQL, but that seems to be the most extreme option.
EDIT: you could also consider using MySQL`s JSON, which has been added recently. That depends on your version of MySQL though.
I didn't try this answer because I don't have any Rails project ready for testing, but I think the problem is in the syntax.
I think it should be something like this:
Lawer.where("lawer_field IN (?)", "2")
Related
I have the following query that works in MYSQL
$query->whereRaw('
ST_Distance_Sphere(
point(address->>"$.longitude", address->>"$.latitude"),
point(?, ?)
) * .000621371192 < ?
', [$longitude, $latitude, $distance]);
When i deployed to heroku im getting this error
SQLSTATE[42703]: Undefined column: 7 ERROR: column "$.longitude" does not exist
LINE 3: point(address->>"$.longitude", address->>"$.latitu...
Im using postgres on heroku and i know the issue is something to do with the json operator.
What is the $.<json key> syntax called? and how do i convert this raw sql query to postgres?
In the worse case i leaning on switching my database to mysql if i cant solve this by Wednesday as it wont be a big deal
Postgres uses double quotes as delimiter for columns, so you must use single quotes to indicate strings. Laravel will take care of it
st_distance_sphere(
st_point(address->>'$.longitude',address->>'$.latitude'),st_point(?, ?)
)
with Rails I hit this:
User.find(:all, :conditions => ["character = ?", character])
character is a Fixnum, as you can see by the way it is translated for the sql. A Fixnum is expected.
Then I get this error:
Mysql2::Error: You have an error in your SQL syntax;
check the manual that corresponds to your MySQL server version for the right syntax to use near '= 5)'
at line 1: SELECT `users`.* FROM `users` WHERE (character = 5)
I'm somewhat confused and absolutely do not get what might be wrong with this line of sql.
Please help.
Yours
Joern
The problem is that character is a keyword in mysql. If you escape it in backticks it should work, eg
User.find(:all, :conditions => ["`character` = ?", character])
When you do a rails find like
User.where(:character => character)
as Rich Peck suggests, then rails automatically escapes the names of all fields to prevent this problem: you can see it do this in your log.
EDIT: you might find it less hassle in the long run to change the name of your column.
ActiveRecord
If using Rails 4, you should use this to look up multiple records:
User.where character: character
If you want to load a specific record, you can just use .find like this:
User.find_by character: character
--
Specific
I think your error is more an ActiveRecord issue than a Fixnum one - the fact you're using that data to look up the records shouldn't have any bearing.
I could be wrong, but I think the bottom line is your use of the ActiveRecord methods you've defined.
I have a complicated query and since I need that my module work on both mysql and postgres, I need to write two version of it.
Unfortunately, I don't know how I can check if the db I use is mysql or postgres, to know which query use. Do you know if a function can return this value?
As #kordirko says, one option is to query the server version: SELECT version(); will work on both MySQL and PostgreSQL, though not most other database engines.
Parsing version strings is always a bit fragile though, and MySQL returns just a version number like 5.5.32 wheras PostgreSQL returns something like PostgreSQL 9.4devel on x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.7.2 20121109 (Red Hat 4.7.2-8), 64-bit. What do you do if you're connecting to a PostgreSQL-compatible database like EnterpriseDB Postgres Plus, or a MySQL-compatible database?
It's much safer to use the Drupal function for the purpose, DatabaseConnection::databaseType. This avoids a query round-trip to the DB, will work on databases that won't understand/accept SELECT version(), and will avoid the need to parse version strings.
You'll find this bug report useful; it suggests that the correct usage is Database::getConnection()->databaseType().
(I've never even used Drupal, I just searched for this).
As long as the abstract DatabaseConnection class extends PDO class, you can invoking pdo methods in order to know the current database driver.
For instance:
$conn = Database::getConnection();
print $conn->getAttribute($conn::ATTR_DRIVER_NAME); #returns mysql, pgsql...
There is a second way to do it using DatabaseConnection::driver():
print $conn->driver();
or DatabaseConnection::databaseType();
print $conn->databaseType();
Note that DatabaseConnection::driver() and DatabaseConnection::databaseType() are similar functions but not equals!
The return value from DatabaseConnection::driver() method depends on the implementation and other factors.
in the Drupal Database API page:
database.inc abstract public DatabaseConnection::driver()
This is not necessarily the same as the type of the database itself. For instance, there could be two MySQL drivers, mysql and mysql_mock. This function would return different values for each, but both would return "mysql" for databaseType().
In the most cases you just gonna want to use only
$conn->getAttribute($conn::ATTR_DRIVER_NAME)
or $conn->databaseType()
If you want get more specific properties, you should take advantage the PHP ReflectionClass features:
$conn = Database::getConnection();
$ref = new ReflectionClass($conn);
#ref->getProperties, ref->getConstants $ref->isAbstract...
Reference:
PDO::getAttribute
PDO::ATTR_DRIVER_NAME
Drupal Database API
Drupal Base Database API class
I'm trying to insert into a remote mysql database. I am able to connect correctly and can query 'select' no problem from it. However, I cannot perform inserts into the same table that I can select from. I suspect it has something to do with my binds, but this is nearly identical to what I was using to get sqlite3 working which I think uses the same Arel to insert.
#result = #db.query("insert into lead_to_processes (case_number, style_of_case) values (?,?)", [
self.case_number.to_blob.force_encoding("UTF-8"),
self.style_of_case.to_blob.force_encoding("UTF-8")
]
)
Ultimate goal is to be able query a remote database from inside of a model and insert data into it. I've tried using Octopus and that didn't quite work because the tables will be different from the databases.
I have full permissions with this user on the database.
So following guidance from comments i changed the syntax and am getting a different error
Mysql2::Error: You have an error in your SQL syntax;
However i'm doing the query like this now
#db = Mysql2::Client.new(connectionstring)
#case_number = #db.escape(self.case_number)
#style_of_case = #db.escape(self.style_of_case)
#db.query("insert into lead_to_processes (case_number, style_of_case) VALUES
(#{#case_number}, #{#style_of_case})
Any ideas or guidance? I've also tried this with '' encapsulating the variables that i'm inserting
I guess there were some weird characters in my code so I had to force UTF-8 encoding and then removed the characters using gsub below, everything is flowing now.
Thanks for the advice
#db.escape(self.style_of_case.force_encoding("UTF-8"))
#db.escape(self.case_number.gsub(/[\xC2]/,'').gsub(/[\xA0]/,'').force_encoding("UTF-8"))
Is it possible that you are missing an end quote?
this
#db.query("insert into lead_to_processes (case_number, style_of_case) VALUES
(#{#case_number}, #{#style_of_case})
should be
#db.query("insert into lead_to_processes (case_number, style_of_case) VALUES
(#{#case_number}, #{#style_of_case}") <== notice the quote at the end.
I have the following code that run on heroku inside a controller that intermittently fails. It's a no-brainer that it should work to me, but I must be missing something.
#artist = Artist.find(params[:artist_id])
The parameters hash looks like this:
{"utf8"=>"������",
"authenticity_token"=>"XXXXXXXXXXXXXXX",
"password"=>"[FILTERED]",
"commit"=>"Download",
"action"=>"show",
"controller"=>"albums",
"artist_id"=>"62",
"id"=>"157"}
The error I get looks like this:
ActiveRecord::StatementInvalid: Mysql::Error: : SELECT `artists`.* FROM `artists` WHERE `artists`.`id` = ? LIMIT 1
notice the WHEREartists.id= ? part of the statement? It's trying to find an ID of QUESTION MARK. Meaning Rails is not passing in the params[:artist_id] which is obviously in the params hash. I'm at complete loss.
I get the same error on different pages trying to select the record in a similar fashion.
My environment: Cedar Stack on Heroku (this only happens on Heroku), Ruby 1.9.3, Rails 3.2.8, files being hosted on Amazon S3 (though I doubt it matters), using the mysql gem (not mysql2, which doesn't work at all), ClearDB MySQL database.
Here's the full trace.
Any help would be tremendously appreciated.
try sql?
If it's just this one statement, and it's causing production problems, can you omit the query generator just for now? In other words, for very short term, just write the SQL yourself. This will buy you a bit of time.
# All on one line:
Artist.find_by_sql
"SELECT `artists`.* FROM `artists`
WHERE `artists`.`id` = #{params[:artist_id].to_i} LIMIT 1"
ARel/MySQL explain?
Rails can help explain what MySQL is trying to do:
Artist.find(params[:artist_id]).explain
http://weblog.rubyonrails.org/2011/12/6/what-s-new-in-edge-rails-explain/
Perhaps you can discover some kind of difference between the queries that are succeeding vs. failing, such as how the explain uses indexes or optimizations.
mysql2 gem?
Can you try changing from the mysql gem to the mysql2 gem? What failure do you get when you switch to the mysql2 gem?
volatility?
Perhaps there's something else changing the params hash on the fly, so you see it when you print it, but it's changed by the time the query runs?
Try assigning the variable as soon as you receive the params:
artist_id = params[:artist_id]
... whatever code here...
#artist = Artist.find(artist_id)
not the params hash?
You wrote "Meaning Rails is not passing in the params[:artist_id] which is obviously in the params hash." I don't think that's the problem-- I expect that you're seeing this because Rails is using the "?" as a placeholder for a prepared statement.
To find out, run the commands suggested by #Mori and compare them; they should be the same.
Article.find(42).to_sql
Article.find(params[:artist_id]).to_sql
prepared statements?
Could be a prepared statement cache problem, when the query is actually executed.
Here's the code that is failing-- and there's a big fat warning.
begin
stmt.execute(*binds.map { |col, val| type_cast(val, col) })
rescue Mysql::Error => e
# Older versions of MySQL leave the prepared statement in a bad
# place when an error occurs. To support older mysql versions, we
# need to close the statement and delete the statement from the
# cache.
stmt.close
#statements.delete sql
raise e
end
Try configuring your database to turn off prepared statements, to see if that makes a difference.
In your ./config/database.yml file:
production:
adapter: mysql
prepared_statements: false
...
bugs with prepared statements?
There may be a problem with Rails ignoring this setting. If you want to know a lot more about it, see this discussion and bug fix by Jeremey Cole and Aaron: https://github.com/rails/rails/pull/7042
Heroku may ignore the setting. Here's a way you can try overriding Heroku by patching the prepared_statements setup: https://github.com/rails/rails/issues/5297
remove the query cache?
Try removing the ActiveRecord QueryCache to see if that makes a difference:
config.middleware.delete ActiveRecord::QueryCache
http://edgeguides.rubyonrails.org/configuring.html#configuring-middle
try postgres?
If you can try Postgres, that could clear it up too. That may not be a long term solution for you, but it would isolate the problem to MySQL.
The MySQL statement is obviously wrong, but the Ruby code you mentioned would not produce it. Something is wrong here, either you use a different Ruby code (maybe one from a before_filter) or pass a different parameter (like params[:artist_id] = "?"). Looks like you use nested resources, something like Artist has_many :albums. Maybe the #artist variable is not initialized correctly in the previous action, so that params[:artist_id] has not the right value?