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97 lines
3 KiB
Markdown
97 lines
3 KiB
Markdown
[](https://travis-ci.org/crystal-lang/crystal-db)
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# crystal-db
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Common db api for crystal. You will need to have a specific driver to access a database.
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* [SQLite](https://github.com/crystal-lang/crystal-sqlite3)
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* [MySQL](https://github.com/crystal-lang/crystal-mysql)
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* [PostgreSQL](https://github.com/will/crystal-pg)
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* [Cassandra](https://github.com/kaukas/crystal-cassandra)
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## Installation
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If you are creating a shard that will work with _any_ driver, then add `crystal-db` as a dependency in `shard.yml`:
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```yaml
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dependencies:
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db:
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github: crystal-lang/crystal-db
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```
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If you are creating an application that will work with _some specific_ driver(s), then add them in `shard.yml`:
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```yaml
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dependencies:
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sqlite3:
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github: crystal-lang/crystal-sqlite3
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```
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`crystal-db` itself will be a nested dependency if drivers are included.
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Note: Multiple drivers can be included in the same application.
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## Documentation
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* [Latest API](http://crystal-lang.github.io/crystal-db/api/latest/)
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* [Crystal book](https://crystal-lang.org/docs/database/)
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## Usage
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This shard only provides an abstract database API. In order to use it, a specific driver for the intended database has to be required as well:
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The following example uses SQLite where `?` indicates the arguments. If PostgreSQL is used `$1`, `$2`, etc. should be used. `crystal-db` does not interpret the statements.
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```crystal
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require "db"
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require "sqlite3"
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DB.open "sqlite3:./file.db" do |db|
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# When using the pg driver, use $1, $2, etc. instead of ?
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db.exec "create table contacts (name text, age integer)"
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db.exec "insert into contacts values (?, ?)", "John Doe", 30
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args = [] of DB::Any
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args << "Sarah"
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args << 33
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db.exec "insert into contacts values (?, ?)", args: args
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puts "max age:"
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puts db.scalar "select max(age) from contacts" # => 33
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puts "contacts:"
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db.query "select name, age from contacts order by age desc" do |rs|
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puts "#{rs.column_name(0)} (#{rs.column_name(1)})"
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# => name (age)
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rs.each do
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puts "#{rs.read(String)} (#{rs.read(Int32)})"
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# => Sarah (33)
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# => John Doe (30)
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end
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end
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end
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```
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## Roadmap
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Issues not yet addressed:
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- [x] Support non prepared statements. [#25](https://github.com/crystal-lang/crystal-db/pull/25)
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- [x] Time data type. (implementation details depends on actual drivers)
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- [x] Data type extensibility. Allow each driver to extend the data types allowed.
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- [x] Transactions & nested transactions. [#27](https://github.com/crystal-lang/crystal-db/pull/27)
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- [x] Connection pool.
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- [ ] Logging
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- [ ] Direct access to `IO` to avoid memory allocation for blobs.
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## Contributing
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1. Fork it ( https://github.com/crystal-lang/crystal-db/fork )
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2. Create your feature branch (git checkout -b my-new-feature)
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3. Commit your changes (git commit -am 'Add some feature')
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4. Push to the branch (git push origin my-new-feature)
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5. Create a new Pull Request
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## Contributors
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- [bcardiff](https://github.com/bcardiff) Brian J. Cardiff - creator, maintainer
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