This is probably something simple I'm missing. I'm working through the pragmatic bookshelf ruby on rails exercises in the AWDWR 4th edition.
Everything was going well and then I ran into the portion where you enter into the sqlite 3 command line tools to make sure it's capturing the order information.
When I try to run the select statement for orders, I get:
sqlite> select * from orders;
SQL error: no such table: orders
Then I tried listing all the tables:
sqlite> .tables
sqlite>
I get to the sqlite command line per the instructions in the book:
sqlite3 -line
Is there something simple I'm missing here?
Thanks.
You need to specify a database filename on your sqlite3 command line. Usually*, if you do not give a database filename, then it will start out operating on an empty, temporary, in-memory database.
*
The version I have at hand (sqlite3 3.7.2) actually takes -line as the database filename if there are no additional arguments. This means that I end up with a file named -line; this file can be deleted with rm ./-line.
You probably want this (run from the root directory of your application):
sqlite3 -line db/development.sqlite3
If your project is using Rails 3, then you can use this:
rails db
If you need the -line behavior, you can use .mode line at the sqlite3 command line.
If you want to access the DB for a non-default environment, just append the environment name:
rails db staging
You can also add in -p if you want to automatically use the username and password from your configuration (sqlite3 does not need a username or password since it uses plain Unix permissions):
rails db -p production
To display all the tables in the sqlite:
>select * from sqlite_master
I had a similar problem (not getting anything back), but I'm using Windows, and it seems to have a problem when I use the drives with the path (c:\ or d:). I was able to solve it by and launching sqllite from the db path, and using only the file name, like this:
C:\mydir\sqlite3.exe -line mydb.db
.tables
or
C:\mydir\sqlite3.exe
.open mydb.db
or
C:\mydir\sqlite3.exe
ATTACH "mydb.db" AS db1;
To display a table:
select * from mytable;
or
select * from db1.mytable;
Go into the db folder by terminal and type
$ sqlite3 development.sqlite3
SQLite version 3.7.7 2011-06-25 16:35:41
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .table
and it will show the tables you have made.
Related
i have multiple databases in my project and i want to open rails console to access both databases.
currently i can fetch data of only one default database.
In other word, how to open specific database console?
In other word, how to open specific database console?
From official guide:
bin/rails dbconsole figures out which database you're using and drops you into whichever command line interface you would use with it (and figures out the command line parameters to give to it, too!). It supports MySQL (including MariaDB), PostgreSQL, and SQLite3.
You can also use the alias "db" to invoke the dbconsole: bin/rails db.
If you are using multiple databases, bin/rails dbconsole will
connect to the primary database by default. You can specify which
database to connect to using --database or --db:
bin/rails dbconsole --database=animals
So command is
rails db --db=db_name_from_database_yml
For example you have in your database.yml
production:
my_primary:
adapter: postgresql
database: some_db_name
In this case your command will be
bundle exec rails db --db=my_primary -e=production
Why don't you have a read through the documentation https://guides.rubyonrails.org/active_record_multiple_databases.html.
You should be able to find just what you need. connects_to does the trick of database switching automatically of manually.
Or
https://api.rubyonrails.org/classes/ActiveRecord/ConnectionHandling.html#method-i-connected_to
ActiveRecord::Base.connected_to(database: :mydb) do
# Do something here...
end
I have a Project-A, and I'm starting Project-B. I want to use Project-A as a starting point. So I copied the files, but how can I duplicate the database? Thank you!
The exact command depends on what type of database you are copying from and too, also on whether you want to copy the structure only or the structure and the content.
A general way to do this would be to export the Project-A database into an SQL file, then run that SQL file through the project-B database. The SQL file can store the structure, or the content or both - you choose when you do the export.
Postgresql uses the command pg_dump to export to SQL. The accepted answer in the question linked to in jdgray's comment shows how the output of pg_dump can be piped directly into the second database so that no intermediate file is created.
To get your database
pg_dump -Fc mydb > db.dump
To restore it:
pg_restore -d <you_new_db_name> /db.dump
This is assuming you are going from pg to pg. All data and structure and relationships will come over with this. I would suggect using pgadmin4 to make the new db before hand so you can just import over to it. In your database.yml change the db name.
If you need addition stuff, like declaring which ip address your db is on use the -p flag. Here is the link to more flags (Postgres v 9.6):
Postgres Link
I just edited the db name from database.yml and ran rake db:create db:migrate
I recently downloaded and install PostgreSQL in Windows. Now how to use PostgreSQL in Ruby on Rails? I search this on the internet but couldn't find any step by step easy solution. I don't understand what do.
.Step 1. Download and install PostgreSQL v9.0.4-1 from here because here said only 9.0.x would be supported on windows 7. I kept all the default options and just used 'secret' as the password when prompted by the Postgres installer for one (again not entirely sure what the consequences of sharing that info on the internet is... will soon find out I'm sure). You'll need this password in step 3.
.Step 2. Change environment variables such that Path (for system, not user (I'm not sure if this is significant or not)) is: C:\Program Files\PostgreSQL\9.0\bin
(n.b. I'm on 64-bit windows hence it not being installed for 32-bit in 'C:\Program Files (x86)\PostgreS...')
Don't forget to change access rights to folder PostgreSQL\9.0 and remove any default readonly rights on the folder or content. (You may also need to restart your computer for these to take effect - thanks #Gavin -although not likely).
.Step 3. Test Postgres installation by trying to create a new database: From command line: createdb -U postgres mydb_as_postgres. You should be prompted to enter the password now, if you're not it may be that you need to start the server first (I can't remember whether I needed to do this or not). The easiest way is through pgAdmin III, which should be 'pgAdmin3.exe' in a folder somewhere like C:\Program Files\PostgreSQL\9.0\bin. Once you've started pgAdmin III there should be a panel on the left called 'Object Browser'. In this there should be a tree with:
Server Groups > Servers > PostgreSQL 9.0 (localhost:5432)
Right click on 'PostgreSQL 9.0 (localhost:5432)' and select 'Connect'.
The createdb -U postgres mydb_as_postgres command should create a new databse called 'mydb_as_postgres' which you can check by firing up pgAdmin III and double clicking on 'PostgreSQL 9.0 (localhost:5432)'. Under this there should be:
Databases (2) which should list 2 databases called mydb_as_postgres and postgres
I called it _as_postgres because the -U postgres part of the command tells Postgres to create the database with the postgres user as it's owner, which you need to specify when you're not signed in as the postgres user. I have all of my files stored as 'AJames' user though so if you're the same and want to keep developing your app when signed in as a different user you need to create a Postgres 'role' for that user now (see step 4).
.Step 4. Through pgAdmin III. Right-click on Login Roles (which for me is in):
Object Browser > Server Groups > Servers > PostgreSQL 9.0 (localhost:5432) > Login Roles
Right-click on Login Roles and select 'New Login Role...' in Role name, put in your operating system user name, which for me is AJames, and fill in your password under the 'Role Privileges' tab, I checked all the boxes, but an experienced postgres user would likely strongly recommend to only check the 'inherits rights from parent roles' and the 'can create database objects' But I'm not an experienced user and just want to debug Rails SQL calls in Postgres so I also checked the 'Superuser' and 'Can create roles', just in case.
.Step 5. You should now be able to create a new database without being signed in as the postgres user. Try typing:
createdb mydb_as_user
Hopefully this should work for you.
.Step 6. Okay, so you've got a development.sqlite3 file in your rails 'db/' directory. Initially I was going to set the next test as converting this from sqlite3 to psql.
I couldn't get this to work though but I left my attempts here as the solution I used required having the data in a Rails app on Heroku.com (see instead the solution from step 7 onwards). For those who only have a local app and no data in Heroku, they can't use the same approach, so they might need to explore something like this:
x6.1 First, test 'psql' by trying a command from your command line like:
psql mydb_as_user
this should display something like below (after you've typed in your password):
C:>psql mydb_as_user
Password:
psql (9.0.4)
WARNING: Console code page (850) differs from Windows code page (1252)
8-bit characters might not work correctly. See psql reference
page "Notes for Windows users" for details.
Type "help" for help.
mydb5=#
x6.2 try entering:
CREATE TABLE users_table (id integer, "name" text);
It should display:
CREATE TABLE
mydb5=#
If you check in pgAdmin III, you should see the table there under:
Object Browser > Server Groups > Servers > PostgreSQL 9.0 (localhost:5432) > Databases > mydb_as_user > Schemas > public > Tables > users_table >
x6.3 Okay, next to try the conversion. Downloaded sqlite-shell precompiled binary for windows.
x6.4 Create a new directory, I used 'C:\temp' and put the sqlite3.exe and your development.sqlite3 files in it.
x6.5 Use the following commands (which are from here) to dump the development.sqlite3 database into Postgres.
sqlite3 development .dump | psql development2
you might get an error like:
psql: FATAL: database "development2" does not exist
x6.6 so I went into pgAdmin III and made a development 2 database, tried the command again and got:
ERROR: syntax error at or near "PRAGMA"
LINE 1: PRAGMA foreign_keys=OFF;
^
BEGIN
COMMIT
Like I said, I couldn't get it to work. I'm sure there's a way of getting round that error but I thought of a different way and so I instead used this solution (which requires a Heroku account to have your data and does the conversion from sqlite3 to psql using the Taps gem (I believe):
.Step 7. in pgAdmin III I created another database. Under the properties tab I set name: 'development', owner: 'AJames' (replace this with your own Windows user name). And under the privileges tab, set role: 'public' and checked the ALL option (thought this resets to unchecked so I'm not sure that's necessary).
.Step 8. add gem 'pg', '0.11.0' to your gem file. You'll probably also want to remove the: gem 'sqlite3' at this point too.
.Step 9. set database.yml as suggested here to:
development:
adapter: postgresql
database: db/development
username: AJames # replace this with your own user name
password: secret # replace this with your own password
host: localhost
encoding: UTF8
pool: 5
timeout: 5000
If you are working on an open source project and don't want your password to be made publicly available, have a look at some of the answers to Securely providing the database password in a Rails app.
.Step 10. from command line in your rails app's root directory run: rake db:migrate This will create the new schema and all the tables in the Postgres database.
.Step 11. run heroku db:pull from your command line (again from in the root directory of your rails app) to pull all your data down and into your new empty Postgres database. I think at this point your taps gem will be doing this work for you.
.Step 12. Hopefully there is no step 12! ...and it should now be working for you. Happy RoR PostgreSQL debugging! Please edit, or let me know, if there are any errors in this.
Good Luck
I'm using the apartment gem for my SaaS (built with Ruby on Rails) and one of its requirements is we need to install the hstore PostgreSQL extension via a dedicated schema (ie: shared_extensions), not the default public schema.
Heroku enables hstore by default; however it is installed in the public schema. When I tried to do:
ActiveRecord::Base.connection.execute("ALTER EXTENSION hstore SET SCHEMA hstore;")
the console returned:
(3.6ms) ALTER EXTENSION hstore SET SCHEMA hstore;
PG::Error: ERROR: must be owner of extension hstore
Currently it's impossible on the code side to make do with hstore extension being installed on public, so I definitely have to find a way to put hstore extension on shared_extensions schema.
Will there be a way to do this on Heroku? Thanks.
A less destructive alternative work around:
1.) Put your application in maintenance mode:
heroku maintenance:on -a [app-name]
2.) Backup up your database: ALWAYS BACK IT UP :)
heroku pg:backups capture -a [app-name]
3.) Copy your database locally:
heroku pg:pull [Database URL] mylocaldb -a [app-name]
4.) Now you have the db locally, you can move the extensions without any destruction of data or columns because you have local superuser priv.:
ALTER EXTENSION "hstore" SET SCHEMA hstore;
5.) Now export this version back to production:
heroku pg:push mylocaldb [Database URL] -a [app-name]
6.) Take your app out of maint. mode and you now have the extensions installed in the shared schema of hstore.
7.) You will still need to perform step 1 of Tu H.'s response if you are on rails < 4.1
OR if you are running rails 4.1+ you can just update your database.yml file:
schema_search_path: "public,hstore"
This is a less destructive way to get what you want done without too much downtime.
Turns out I can't do ALTER EXTENSION hstore SET SCHEMA hstore; on Heroku. I've documented the workaround here
Append ?schema_search_path=public,hstore to your DATABASE_URL environment variable, by this you don't have to revise the database.yml file (which is impossible since Heroku regenerates a completely different and immutable database.yml of its own on each deploy)
Run heroku pg:psql from your command line
And then DROP EXTENSION hstore; (Note: This will drop all columns that use hstore type, so proceed with caution; only do this with a fresh PostgreSQL instance)
Next: CREATE SCHEMA IF NOT EXISTS hstore;
Finally: CREATE EXTENSION IF NOT EXISTS hstore SCHEMA hstore; and hit enter (\q to exit)
Currently I get the following error:
PGError (FATAL: password authentication failed for user "postgres" ):
when my app tries to access the database.
I wanted to test my SQL calls against postgres as my app regular breaks when pushed up to production on Heroku because of the stricter requirements of postgres (which I think is probably a healthy thing) over sqlite 3. So I have a similar request to this for a not out of date tutorial for installing postgres for use with ruby on rails on windows (7) please. I thought it'd be a quick 20 minutes of downloading and installing but 2 and a bit hours later and I don't think I'm very close yet. So far I've:
Downloaded and installed Postgres Version 8.4.8-1 from here
Set my environment variables such that Path (for User) is: C:\Ruby192\bin;C:\Program Files (x86)\PostgreSQL\8.4\bin
Gemfile:
gem 'pg', '0.11.0' # instead of gem 'sqlite3', '1.3.3'
ran bundle install for my rails app seemingly successfully, but haven't found easy way to validate installation yet.
set database.yml as suggested here to:
development:
adapter: postgresql
database: db/development
username: postgres
password: secret
host: localhost
encoding: UTF8
pool: 5
timeout: 5000
I know I need to set up a user name and password for Postgres, maybe also start the postgres server, connect to it(?) and put in my local IP address I'll connect to it on into a config files somewhere and then edit one of the other .conf files in 'C:\Program Files (x86)\PostgreSQL\8.4\data' etc...
I think Rails has made me soft, am I over thinking things or is it actually fairly tricky to set up and I should just go back to Sqlite3, for which there's also the awesomely useful SQLite Manager, Firefox plugin?
I'm still searching for a beginners guide to installing and using Postgres for rails but so far have only been confused by most of the stuff I look at / tried following like this, this, this, this, this(for Snow Leopard), this(linux).
Any pointers would be much appreciated. Thanks!
James
An approach to installing Postgres on windows 7 for use as PostgreSQL database for a rails 3 (3.0.7) project.
Preamble (you can skip this bit)
So the first thing to point out is that Postgres is not just a different file extension from .sqlite3, it's a whole mechanism for managing your databases. As such it has a client/server model, of which you'll need to set up both to use Postgres as the database for your rails app.
Motivation for going through considerable pain of Postgres setup versus almost effortless sqlite setup: if you're deploying to Heroku, they're currently using Postgres so some of your SQL calls that are fine on sqlite3 will break when used with Postgres. It's much easier to debug postgres locally rather than when it's on Heroku's servers.
So I did the following things:
(Disclaimer: I may have forgotten to include some of the things I did... it took me over 48 hours of on and off pain to get it to work... if the following advice doesn't work for you then the huge (2300 pages!!) but very thorough Postgres documentation should help. I'd recommend downloading this anyway if you're serious about using Postgres as it has a lot of material that I've only just begun to understand the significance of.)
(Second disclaimer: I have almost certainly broken 20 sensible Postgres guidelines and exposed security holes in the Postgres database whilst doing so. If there any obvious things an experienced Postgres user disagrees with, please edit my post.)
.Step 1. Download and install PostgreSQL v9.0.4-1 from here because here said only 9.0.x would be supported on windows 7. I kept all the default options and just used 'secret' as the password when prompted by the Postgres installer for one (again not entirely sure what the consequences of sharing that info on the internet is... will soon find out I'm sure). You'll need this password in step 3.
.Step 2. Change environment variables such that Path (for system, not user (I'm not sure if this is significant or not)) is: C:\Program Files\PostgreSQL\9.0\bin
(n.b. I'm on 64-bit windows hence it not being installed for 32-bit in 'C:\Program Files (x86)\PostgreS...')
Don't forget to change access rights to folder PostgreSQL\9.0 and remove any default readonly rights on the folder or content.
(You may also need to restart your computer for these to take effect - thanks #Gavin -although not likely).
.Step 3. Test Postgres installation by trying to create a new database:
From command line: createdb -U postgres mydb_as_postgres.
You should be prompted to enter the password now, if you're not it may be that you need to start the server first (I can't remember whether I needed to do this or not). The easiest way is through pgAdmin III, which should be 'pgAdmin3.exe' in a folder somewhere like C:\Program Files\PostgreSQL\9.0\bin. Once you've started pgAdmin III there should be a panel on the left called 'Object Browser'. In this there should be a tree with:
Server Groups > Servers > PostgreSQL 9.0 (localhost:5432)
Right click on 'PostgreSQL 9.0 (localhost:5432)' and select 'Connect'.
The createdb -U postgres mydb_as_postgres command should create a new databse called 'mydb_as_postgres' which you can check by firing up pgAdmin III and double clicking on 'PostgreSQL 9.0 (localhost:5432)'. Under this there should be:
Databases (2) which should list 2 databases called mydb_as_postgres and postgres
I called it _as_postgres because the -U postgres part of the command tells Postgres to create the database with the postgres user as it's owner, which you need to specify when you're not signed in as the postgres user. I have all of my files stored as 'AJames' user though so if you're the same and want to keep developing your app when signed in as a different user you need to create a Postgres 'role' for that user now (see step 4).
.Step 4. Through pgAdmin III. Right-click on Login Roles (which for me is in):
Object Browser > Server Groups > Servers > PostgreSQL 9.0 (localhost:5432) > Login Roles
Right-click on Login Roles and select 'New Login Role...'
in Role name, put in your operating system user name, which for me is AJames,
and fill in your password under the 'Role Privileges' tab, I checked all the boxes, but an experienced postgres user would likely strongly recommend to only check the 'inherits rights from parent roles' and the 'can create database objects' But I'm not an experienced user and just want to debug Rails SQL calls in Postgres so I also checked the 'Superuser' and 'Can create roles', just in case.
.Step 5. You should now be able to create a new database without being signed in as the postgres user. Try typing:
createdb mydb_as_user
Hopefully this should work for you.
.Step 6. Okay, so you've got a development.sqlite3 file in your rails 'db/' directory. Initially I was going to set the next test as converting this from sqlite3 to psql.
I couldn't get this to work though but I left my attempts here as the solution I used required having the data in a Rails app on Heroku.com (see instead the solution from step 7 onwards). For those who only have a local app and no data in Heroku, they can't use the same approach, so they might need to explore something like this:
x6.1 First, test 'psql' by trying a command from your command line like:
psql mydb_as_user
this should display something like below (after you've typed in your password):
C:>psql mydb_as_user
Password:
psql (9.0.4)
WARNING: Console code page (850) differs from Windows code page (1252)
8-bit characters might not work correctly. See psql reference
page "Notes for Windows users" for details.
Type "help" for help.
mydb5=#
x6.2 try entering:
CREATE TABLE users_table (id integer, "name" text);
It should display:
CREATE TABLE
mydb5=#
If you check in pgAdmin III, you should see the table there under:
Object Browser > Server Groups > Servers > PostgreSQL 9.0 (localhost:5432) > Databases > mydb_as_user > Schemas > public > Tables > users_table >
x6.3 Okay, next to try the conversion. Downloaded sqlite-shell precompiled binary for windows.
x6.4 Create a new directory, I used 'C:\temp' and put the sqlite3.exe and your development.sqlite3 files in it.
x6.5 Use the following commands (which are from here) to dump the development.sqlite3 database into Postgres.
sqlite3 development .dump | psql development2
you might get an error like:
psql: FATAL: database "development2" does not exist
x6.6 so I went into pgAdmin III and made a development 2 database, tried the command again and got:
ERROR: syntax error at or near "PRAGMA"
LINE 1: PRAGMA foreign_keys=OFF;
^
BEGIN
COMMIT
Like I said, I couldn't get it to work. I'm sure there's a way of getting round that error but I thought of a different way and so I instead used this solution (which requires a Heroku account to have your data and does the conversion from sqlite3 to psql using the Taps gem (I believe):
.Step 7. in pgAdmin III I created another database. Under the properties tab I set name: 'development', owner: 'AJames' (replace this with your own Windows user name). And under the privileges tab, set role: 'public' and checked the ALL option (thought this resets to unchecked so I'm not sure that's necessary).
.Step 8. add
gem 'pg', '0.11.0'
to your gem file. You'll probably also want to remove the:
gem 'sqlite3'
at this point too.
.Step 9. set database.yml as suggested here to:
development:
adapter: postgresql
database: db/development
username: AJames # replace this with your own user name
password: secret # replace this with your own password
host: localhost
encoding: UTF8
pool: 5
timeout: 5000
If you are working on an open source project and don't want your password to be made publicly available, have a look at some of the answers to Securely providing the database password in a Rails app.
.Step 10. from command line in your rails app's root directory run:
rake db:migrate
This will create the new schema and all the tables in the Postgres database.
.Step 11. run heroku db:pull from your command line (again from in the root directory of your rails app) to pull all your data down and into your new empty Postgres database. I think at this point your taps gem will be doing this work for you.
.Step 12. Hopefully there is no step 12! ...and it should now be working for you. Happy RoR PostgreSQL debugging! Please edit, or let me know, if there are any errors in this.
Also, here's a list of additional stuff that might be interesting/useful:
This is a blog post about Postgres passwords, what they're for,
why you need them, how to change them etc.
This, under 'Creating a spatial database', is useful for newbies to
understand what pg_hba.conf is about and the second link that
Reno gave above, under the 'Using pgAdmin III GUI' is useful to
testing to see if postgres is actually working, before trying to fit
it with Rails (i.e. try creating a database and putting a table and
some data into it).
In the huge but very comprehensive Postgres documentation, I'd
start on page 58, 'I. tutorial'. Then on pdf page 431(!) there's
'Chapter 17. Server setup and operation' that I also found useful.
the answer from AJP is the correct one with just a small re-config.
The line
database: db/development
does not work for me.
I have to change it to
database: development
I use this for ruby on rails for the command
rake db:create
and
rake db:migrate
to work
None of your links appeared to be the (arguably) most useful documentation - the official postgresql docs. I recently configure a Linux Mint box with postgresql and django using a combination of those documents and these, though the latter are specific to Linux.
I'd worry more about validating the postgresql side of things, less about rails. That is to say, your question should be "How can I set up and test a postgresql server on a Windows 7 box", moreso than you need to know how to get it locked into rails.
Edit:
Maybe this could also be of use to you - official postgresql wiki with detailed installation guides.
Good luck!