Class: Tina4::Drivers::PostgresDriver

Inherits:
Object
  • Object
show all
Includes:
SchemaSplit
Defined in:
lib/tina4/drivers/postgres_driver.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from SchemaSplit

#split_schema

Instance Attribute Details

#connection ⇒ Object (readonly)

Returns the value of attribute connection.



9
10
11
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 9

def connection
  @connection
end

Instance Method Details

#apply_limit(sql, limit, offset = 0) ⇒ Object 



104
105
106
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 104

def apply_limit(sql, limit, offset = 0)
  "#{sql} LIMIT #{limit} OFFSET #{offset}"
end

#begin_transaction ⇒ Object 



108
109
110
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 108

def begin_transaction
  @connection.exec("BEGIN")
end

#close ⇒ Object 



32
33
34
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 32

def close
  @connection&.close
end

#columns(table_name) ⇒ Object 



137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 137

def columns(table_name)
  # v3.13.14 (#48): honour a schema-qualified name; default to public.
  schema, tbl = split_schema(table_name)
  schema ||= "public"
  sql = "SELECT column_name, data_type, is_nullable, column_default FROM information_schema.columns WHERE table_name = $1 AND table_schema = $2"
  rows = execute_query(sql, [tbl, schema])
  rows.map do |r|
    {
      name: r[:column_name],
      type: r[:data_type],
      nullable: r[:is_nullable] == "YES",
      default: r[:column_default],
      primary_key: false
    }
  end
end

#commit ⇒ Object 



112
113
114
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 112

def commit
  @connection.exec("COMMIT")
end

#connect(connection_string, username: nil, password: nil) ⇒ Object 



11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 11

def connect(connection_string, username: nil, password: nil)
  begin
    require "pg"
  rescue LoadError
    raise LoadError,
          "The 'pg' gem is required for PostgreSQL connections. Install one of:\n" \
          "    bundle add pg     # if your project uses Bundler\n" \
          "    gem install pg    # bare driver"
  end
  url = connection_string
  if username || password
    uri = URI.parse(url)
    uri.user = username if username
    uri.password = password if password
    url = uri.to_s
  end
  @connection = PG.connect(url)
  apply_result_type_map(@connection)
  @connection
end

#execute(sql, params = []) ⇒ Object 



46
47
48
49
50
51
52
53
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 46

def execute(sql, params = [])
  converted_sql = convert_placeholders(sql)
  if params.empty?
    @connection.exec(converted_sql)
  else
    @connection.exec_params(converted_sql, params)
  end
end

#execute_query(sql, params = []) ⇒ Object 



36
37
38
39
40
41
42
43
44
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 36

def execute_query(sql, params = [])
  converted_sql = convert_placeholders(sql)
  result = if params.empty?
             @connection.exec(converted_sql)
           else
             @connection.exec_params(converted_sql, params)
           end
  result.map { |row| decode_blobs(symbolize_keys(row)) }
end

#last_insert_id ⇒ Object 



55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 55

def last_insert_id
  # Issue #38: ``SELECT lastval()`` raises on tables with no sequence
  # (UUID, ULID, hash PKs etc.). The exception itself isn't fatal,
  # but the pg gem marks the whole transaction as aborted, so every
  # subsequent statement on this connection fails with
  # ``PG::InFailedSqlTransaction`` — far away from the real cause.
  #
  # Fix: wrap the probe in a SAVEPOINT. If ``lastval()`` raises, we
  # ROLLBACK TO SAVEPOINT and the outer transaction stays usable;
  # ``last_insert_id`` just returns ``nil`` (same as before for
  # tables without a sequence). On success we RELEASE SAVEPOINT.
  begin
    @connection.exec("SAVEPOINT _t4_lastval_probe")
  rescue PG::Error
    # No active transaction (autocommit/idle) — fall back to a plain
    # probe; psycopg2-style transaction abort can't happen here.
    begin
      result = @connection.exec("SELECT lastval()")
      return result.first["lastval"].to_i
    rescue PG::Error
      return nil
    end
  end

  begin
    result = @connection.exec("SELECT lastval()")
    @connection.exec("RELEASE SAVEPOINT _t4_lastval_probe")
    result.first["lastval"].to_i
  rescue PG::Error
    begin
      @connection.exec("ROLLBACK TO SAVEPOINT _t4_lastval_probe")
      @connection.exec("RELEASE SAVEPOINT _t4_lastval_probe")
    rescue PG::Error
      # If even the rollback fails, there's nothing we can do — the
      # connection is in a state we can't recover. Surface nil so
      # callers don't get a half-set last_id.
    end
    nil
  end
end

#placeholder ⇒ Object 



96
97
98
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 96

def placeholder
  "?"
end

#placeholders(count) ⇒ Object 



100
101
102
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 100

def placeholders(count)
  (1..count).map { |i| "$#{i}" }.join(", ")
end

#rollback ⇒ Object 



116
117
118
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 116

def rollback
  @connection.exec("ROLLBACK")
end

#table_exists?(name) ⇒ Boolean

v3.13.14 (#48): to_regclass resolves a (possibly schema-qualified) relation name and search_path like a FROM clause; nil if absent.

Returns:

  • (Boolean) 


122
123
124
125
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 122

def table_exists?(name)
  rows = execute_query("SELECT to_regclass($1) AS oid", [name.to_s])
  !rows.empty? && !rows[0][:oid].nil?
end

#tables ⇒ Object 



127
128
129
130
131
132
133
134
135
 
# File 'lib/tina4/drivers/postgres_driver.rb', line 127

def tables
  # v3.13.14 (#48): list every user schema; public tables stay bare,
  # others are returned schema-qualified.
  sql = "SELECT schemaname, tablename FROM pg_tables " \
        "WHERE schemaname NOT IN ('pg_catalog', 'information_schema') " \
        "ORDER BY schemaname, tablename"
  rows = execute_query(sql)
  rows.map { |r| r[:schemaname] == "public" ? r[:tablename] : "#{r[:schemaname]}.#{r[:tablename]}" }
end