Class: Pod4::PgInterface

Inherits:
Interface show all
Includes:
SQLHelper
Defined in:
lib/pod4/pg_interface.rb

Overview

Pod4 Interface for requests on a SQL table via pg, the PostgresQL adapter.

If your DB table is one-one with your model, you shouldn’t need to override anything. Example:

class CustomerInterface < SwingShift::PgInterface
  set_schema :public    # optional
  set_table  :customer
  set_id_fld :id, autoincrement: true
end

Constant Summary

Constants inherited from Interface

Interface::ACTIONS

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from SQLHelper

#quoted_table

Methods included from Metaxing

#define_class_method, #metaclass

Constructor Details

#initialize(arg) ⇒ PgInterface

Initialise the interface by passing it a Pg connection hash, or a Pod4::ConnectionPool object.



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# File 'lib/pod4/pg_interface.rb', line 83

def initialize(arg)
  case arg
    when Hash
      @connection = ConnectionPool.new(interface: self.class)
      @connection.data_layer_options = arg

    when ConnectionPool
      @connection = arg

    else
      raise ArgumentError, "Bad argument"
  end

rescue => e
  handle_error(e)
end

Instance Attribute Details

#id_fld ⇒ Object (readonly)

Returns the value of attribute id_fld.



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# File 'lib/pod4/pg_interface.rb', line 30

def id_fld
  @id_fld
end

Class Method Details

.id_ai ⇒ Object

Raises:



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# File 'lib/pod4/pg_interface.rb', line 73

def id_ai
  raise Pod4Error, "You need to use set_id_fld to set the ID column"
end

.id_fld ⇒ Object

Raises:



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# File 'lib/pod4/pg_interface.rb', line 69

def id_fld
  raise Pod4Error, "You need to use set_id_fld to set the ID column"
end

.schema ⇒ Object 



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# File 'lib/pod4/pg_interface.rb', line 45

def schema; nil; end

.set_id_fld(idFld, opts = {}) ⇒ Object

Set the name of the column that holds the unique id for the table.



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# File 'lib/pod4/pg_interface.rb', line 63

def set_id_fld(idFld, opts={})
  ai = opts.fetch(:autoincrement) { true }
  define_class_method(:id_fld) {idFld.to_s.to_sym}
  define_class_method(:id_ai)  {!!ai}
end

.set_schema(schema) ⇒ Object

Set the name of the schema. This is optional.



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# File 'lib/pod4/pg_interface.rb', line 41

def set_schema(schema) 
  define_class_method(:schema) {schema.to_s.to_sym}
end

.set_table(table) ⇒ Object

Set the name of the database table



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# File 'lib/pod4/pg_interface.rb', line 51

def set_table(table)
  define_class_method(:table) {table.to_s.to_sym}
end

.table ⇒ Object

Raises:



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# File 'lib/pod4/pg_interface.rb', line 55

def table
  raise Pod4Error, "You need to use set_table to set the table name"
end

Instance Method Details

#_connection ⇒ Object

Expose @connection, for testing only.



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# File 'lib/pod4/pg_interface.rb', line 335

def _connection
  @connection
end

#close_connection(conn) ⇒ Object

Close the connection to the database.

Pod4 itself doesn’t use this(?)



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# File 'lib/pod4/pg_interface.rb', line 324

def close_connection(conn)
  Pod4.logger.info(__FILE__){ "Closing connection to DB" }
  conn.finish unless conn.nil?

rescue => e
  handle_error(e)
end

#create(record) ⇒ Object

Record is a hash or octothorpe of field: value

By a happy coincidence, insert returns the unique ID for the record, which is just what we want to do, too.



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# File 'lib/pod4/pg_interface.rb', line 122

def create(record)
  raise Octothorpe::BadHash if record.nil?
  ot = Octothorpe.new(record)

  if id_ai
    ot = ot.reject{|k,_| k == id_fld}
  else
    raise(ArgumentError, "ID field missing from record") if ot[id_fld].nil?
  end

  sql, vals = sql_insert(ot) 
  x = selectp(sql, *vals)
  x.first[id_fld]

rescue Octothorpe::BadHash
  raise ArgumentError, "Bad type for record parameter"
rescue
  handle_error $!
end

#delete(id) ⇒ Object

ID is whatever you set in the interface using set_id_fld



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# File 'lib/pod4/pg_interface.rb', line 183

def delete(id)
  read_or_die(id)

  sql, vals = sql_delete(id_fld => id)
  executep(sql, *vals)

  self

rescue => e
  handle_error(e)
end

#execute(sql) ⇒ Object

Run SQL code on the server; return true or false for success or failure



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# File 'lib/pod4/pg_interface.rb', line 274

def execute(sql)
  raise(ArgumentError, "Bad SQL parameter") unless sql.kind_of?(String)

  client = ensure_connection
  Pod4.logger.debug(__FILE__){ "execute: #{sql}" }
  client.exec(sql)

rescue => e
  handle_error(e)
end

#executep(sql, *vals) ⇒ Object

Run SQL code on the server as per execute() but with parameter insertion.

Placeholders in the SQL string should all be %s as per sql_helper methods. Values should be as returned by sql_helper methods.



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# File 'lib/pod4/pg_interface.rb', line 291

def executep(sql, *vals)
  raise(ArgumentError, "Bad SQL parameter") unless sql.kind_of?(String)

  client = ensure_connection
  Pod4.logger.debug(__FILE__){ "parameterised execute: #{sql}" }
  client.exec_params( *parse_for_params(sql, vals) )

rescue => e
  handle_error(e)
end

#id_ai ⇒ Object 



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# File 'lib/pod4/pg_interface.rb', line 103

def id_ai;  self.class.id_ai;  end

#list(selection = nil) ⇒ Object 



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# File 'lib/pod4/pg_interface.rb', line 105

def list(selection=nil)
  raise(ArgumentError, 'selection parameter is not a hash') \
    unless selection.nil? || selection.respond_to?(:keys)

  sql, vals = sql_select(nil, selection)
  selectp(sql, *vals) {|r| Octothorpe.new(r) }

rescue => e
  handle_error(e)
end

#new_connection(params) ⇒ Object

Open the connection to the database.

This is called from a Connection Object.



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# File 'lib/pod4/pg_interface.rb', line 307

def new_connection(params)
  Pod4.logger.info(__FILE__){ "Connecting to DB" }

  client = PG.connect(params)
  raise DataBaseError, "Bad Connection" unless client.status == PG::CONNECTION_OK

  client

rescue => e
  handle_error(e)
end

#read(id) ⇒ Object

ID corresponds to whatever you set in set_id_fld



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# File 'lib/pod4/pg_interface.rb', line 145

def read(id)
  raise(ArgumentError, "ID parameter is nil") if id.nil?

  sql, vals = sql_select(nil, id_fld => id) 
  rows = selectp(sql, *vals)
  Octothorpe.new(rows.first)

rescue => e
  # Select has already wrapped the error in a Pod4Error, but in this case we want to catch
  # something. Ruby 2.0 doesn't define Exception.cause, but in that case, we do on Pod4Error.
  raise CantContinue, "That doesn't look like an ID" \
    if e.respond_to?(:cause) && e.cause.class == PG::InvalidTextRepresentation

  handle_error(e)
end

#schema ⇒ Object 



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# File 'lib/pod4/pg_interface.rb', line 100

def schema; self.class.schema; end

#select(sql) ⇒ Object

Run SQL code on the server. Return the results.

Will return an array of records, or you can use it in block mode, like this:

select("select * from customer") do |r|
  # r is a single record
end

The returned results will be an array of hashes (or if you passed a block, of whatever you returned from the block).



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# File 'lib/pod4/pg_interface.rb', line 207

def select(sql)
  raise(ArgumentError, "Bad SQL parameter") unless sql.kind_of?(String)

  client = ensure_connection
  Pod4.logger.debug(__FILE__){ "select: #{sql}" }

  rows = []
  client.exec(sql) do |query|
    oids = make_oid_hash(query)

    query.each do |r| 
      row = cast_row_fudge(r, oids)

      if block_given? 
        rows << yield(row)
      else
        rows << row
      end

    end
  end

  client.cancel 
  rows

rescue => e
  handle_error(e)
end

#selectp(sql, *vals) ⇒ Object

Run SQL code on the server as per select() but with parameter insertion.

Placeholders in the SQL string should all be %s as per sql_helper methods. Values should be as returned by sql_helper methods.



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# File 'lib/pod4/pg_interface.rb', line 242

def selectp(sql, *vals)
  raise(ArgumentError, "Bad SQL parameter") unless sql.kind_of?(String)

  client = ensure_connection
  Pod4.logger.debug(__FILE__){ "select: #{sql} #{vals.inspect}" }

  rows = []
  client.exec_params( *parse_for_params(sql, vals) ) do |query|
    oids = make_oid_hash(query)

    query.each do |r| 
      row = cast_row_fudge(r, oids)

      if block_given? 
        rows << yield(row)
      else
        rows << row
      end

    end
  end

  client.cancel 
  rows

rescue => e
  handle_error(e)
end

#table ⇒ Object 



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# File 'lib/pod4/pg_interface.rb', line 101

def table;  self.class.table;  end

#update(id, record) ⇒ Object

ID is whatever you set in the interface using set_id_fld; record should be a Hash or Octothorpe.



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# File 'lib/pod4/pg_interface.rb', line 165

def update(id, record)
  raise(ArgumentError, "Bad type for record parameter") \
    unless record.kind_of?(Hash) || record.kind_of?(Octothorpe)

  read_or_die(id)

  sql, vals = sql_update(record, id_fld => id)
  executep(sql, *vals)

  self

rescue => e
  handle_error(e)
end