Class: DBI::BaseDatabase

Inherits:
Base
  • Object
show all
Defined in:
lib/dbi/base_classes/database.rb

Overview

Provides the core-level functionality for DatabaseHandles.

If the method description says “DBD Required”, it’s the DBD’s responsibility to create this method.

Required methods unimplemented by the DBD will raise DBD::NotImplementedError.

“DBD Optional” methods are methods that do not have a default implementation but are optional due to the fact that many databases may not support these features (and emulating them would be prohibitive).

These methods raise DBI::NotSupportedError.

Otherwise, DBI will provide a general alternative which should meet the expectations of the documentation. However, DBDs can override every method in this class.

Direct Known Subclasses

DBD::MSSQL::Database

Instance Method Summary collapse

Constructor Details

#initialize(handle, attr) ⇒ BaseDatabase

Returns a new instance of BaseDatabase.



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# File 'lib/dbi/base_classes/database.rb', line 22

def initialize(handle, attr)
  @handle = handle
  @attr   = {}
  attr.each {|k, v| self[k] = v}
end

Instance Method Details

#[](attr) ⇒ Object

Get an attribute from the DatabaseHandle. These are DBD specific and embody things like Auto-Commit support for transactional databases.

DBD Authors

This messes with @attr directly.



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# File 'lib/dbi/base_classes/database.rb', line 127

def [](attr)
  @attr[attr]
end

#[]=(attr, value) ⇒ Object

Set an attribute on the DatabaseHandle. DBD Optional.

Raises:



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# File 'lib/dbi/base_classes/database.rb', line 132

def []=(attr, value)
  raise NotSupportedError
end

#columns(table) ⇒ Object

Return a map of the columns that exist in the provided table name. DBD Required.

The result should be an array of DBI::ColumnInfo objects which have, at minimum, the following fields:

  • name

    the name of the column.

  • type

    This is not a field name in itself. You have two options:

    • type_name

      The name of the type as returned by the database

    • dbi_type

      A DBI::Type-conforming class that can be used to convert to a native type.

  • precision

    the precision (generally length) of the column

  • scale

    the scale (generally a secondary attribute to precision

    that helps indicate length) of the column

Raises:



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# File 'lib/dbi/base_classes/database.rb', line 60

def columns(table)
  raise NotImplementedError
end

#commit ⇒ Object

Schedule a commit to the database immediately. DBD Optional.

Raises:



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# File 'lib/dbi/base_classes/database.rb', line 69

def commit
  raise NotSupportedError
end

#disconnect ⇒ Object

Disconnect from the database. DBD Required.

Raises:



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# File 'lib/dbi/base_classes/database.rb', line 29

def disconnect
  raise NotImplementedError
end

#do(statement, bindvars) ⇒ Object

Execute and complete the statement with the binds provided. Returns the row modified count (via BaseStatement#rows). Finishes the statement handle for you.

Roughly equivalent to:

sth = dbh.prepare("my statement)
sth.execute(my, bind, vars)
result = sth.rows
sth.finish

Returning the value stored in ‘result`.



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# File 'lib/dbi/base_classes/database.rb', line 114

def do(statement, bindvars)
  stmt = execute(statement, bindvars)
  res = stmt.rows
  stmt.finish
  return res
end

#execute(statement, bindvars = {}) ⇒ Object

Execute a statement with the binds provided. Returns the statement handle unfinished.

This is roughly equivalent to:

sth = dbh.prepare("my statement")
sth.execute(my, bind, vars)



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# File 'lib/dbi/base_classes/database.rb', line 94

def execute(statement, bindvars={})
  stmt = prepare(statement)
  stmt.bind_params(bindvars) 
  stmt.execute
  stmt
end

#ping ⇒ Object

Ping the database to ensure the connection is still alive. Boolean return, true for success. DBD Required.

Raises:



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# File 'lib/dbi/base_classes/database.rb', line 35

def ping
  raise NotImplementedError
end

#prepare(statement) ⇒ Object

Prepare a cached statement, returning a StatementHandle. DBD Required.

Raises:



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# File 'lib/dbi/base_classes/database.rb', line 41

def prepare(statement)
  raise NotImplementedError
end

#rollback ⇒ Object

Schedule a rollback to the database immediately. DBD Optional.

Raises:



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# File 'lib/dbi/base_classes/database.rb', line 74

def rollback
  raise NotSupportedError
end

#tables ⇒ Object

Return the tables available to the database connection.

Note

the basic implementation returns an empty array.



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# File 'lib/dbi/base_classes/database.rb', line 81

def tables
  []
end