Module: PostgresHelper

Defined in:
lib/db/postgres.rb

Class Method Summary collapse

Class Method Details

.connect_to_postgres(config) ⇒ Object 



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# File 'lib/db/postgres.rb', line 8

def connect_to_postgres(config)
  conn = PG.connect(
    host: config[:host],
    port: config[:port],
    dbname: config[:database],
    user: config[:username],
    password: config[:password],
    sslmode: config[:sslmode] || 'prefer',
    gssencmode: 'disable',  # Disable GSSAPI encryption
    krbsrvname: nil,        # Disable Kerberos service name
    target_session_attrs: 'read-write'
  )
  conn
end

.disconnect_from_postgres(client) ⇒ Object 



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# File 'lib/db/postgres.rb', line 23

def disconnect_from_postgres(client)
  client.close if client.respond_to?(:close)
end

.format_postgres_config(connection_string) ⇒ Object 



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# File 'lib/db/postgres.rb', line 157

def format_postgres_config(connection_string)
  parsed = URI.parse(connection_string)
  
  {
    host: parsed.host,
    port: parsed.port || 5432,
    database: parsed.path[1..-1],
    username: parsed.user || 'postgres',
    password: parsed.password || '',
    sslmode: parsed.query&.split('&')&.find { |param| param.start_with?('sslmode=') }&.split('=')&.last || 'prefer'
  }
end

.get_columns_by_table_postgres(client, schema_name, table_name) ⇒ Object 



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# File 'lib/db/postgres.rb', line 76

def get_columns_by_table_postgres(client, schema_name, table_name)
  sql = <<~SQL
    SELECT column_name 
    FROM information_schema.columns 
    WHERE table_schema = '#{schema_name}' 
    AND table_name = '#{table_name}'
    ORDER BY ordinal_position
  SQL
  
  results = run_query_postgres(sql, client)
  results[:rows].map { |row| row['column_name'] }
end

.get_foreign_keys_postgres(client, schema_name, table_name, primary_key) ⇒ Object 



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# File 'lib/db/postgres.rb', line 89

def get_foreign_keys_postgres(client, schema_name, table_name, primary_key)
  depluralized_table_name = table_name.singularize
  
  sql = <<~SQL
    SELECT column_name 
    FROM information_schema.columns 
    WHERE table_schema = '#{schema_name}' 
    AND table_name != '#{table_name}' 
    AND (column_name = '#{primary_key}' 
      OR column_name = '#{depluralized_table_name}_#{primary_key}' 
      OR column_name = '#{depluralized_table_name}#{primary_key.capitalize}')
  SQL

  results = run_query_postgres(sql, client)
  foreign_keys = results[:rows].map { |key| key['column_name'] }
  
  foreign_keys = foreign_keys.reject { |key| ['id', '_id_'].include?(key) }
  foreign_keys = foreign_keys.uniq

  if foreign_keys.empty?
    sql = <<~SQL
      SELECT column_name 
      FROM information_schema.columns 
      WHERE table_schema = '#{schema_name}' 
      AND table_name != '#{table_name}' 
      AND (column_name LIKE '#{table_name}%' 
        OR column_name LIKE '%\\_id' 
        OR column_name LIKE '%Id' 
        OR column_name LIKE '%\\_#{primary_key}' 
        OR column_name LIKE '%#{primary_key.capitalize}')
    SQL

    results = run_query_postgres(sql, client)
    foreign_keys = results[:rows].map { |key| key['column_name'] }.uniq
  end

  foreign_keys
end

.get_schema_column_info_postgres(client, schema_name, table_names) ⇒ Object 



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# File 'lib/db/postgres.rb', line 128

def get_schema_column_info_postgres(client, schema_name, table_names)
  table_names.map do |table_name|
    query = <<~SQL
      SELECT 
        column_name,
        udt_name as field_type,
        ordinal_position as sort_number
      FROM information_schema.columns
      WHERE table_schema = '#{table_name[:schemaName]}'
      AND table_name = '#{table_name[:tableName]}'
      ORDER BY sort_number
    SQL

    results = run_query_postgres(query, client)
    {
      tableName: "#{table_name[:schemaName]}.#{table_name[:tableName]}",
      displayName: "#{table_name[:schemaName]}.#{table_name[:tableName]}",
      columns: results[:rows].map do |row|
        {
          columnName: row['column_name'],
          displayName: row['column_name'],
          dataTypeID: get_pg_type_oid(row['field_type']),
          fieldType: row['field_type']
        }
      end
    }
  end
end

.get_schemas_postgres(client) ⇒ Object 



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# File 'lib/db/postgres.rb', line 43

def get_schemas_postgres(client)
  sql = <<~SQL
    SELECT schema_name 
    FROM information_schema.schemata 
    WHERE schema_name NOT LIKE 'pg_%' 
    AND schema_name != 'information_schema'
  SQL
  
  results = run_query_postgres(sql, client)
  results[:rows].map { |row| row['schema_name'] }
end

.get_tables_by_schema_postgres(client, schema_names) ⇒ Object 



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# File 'lib/db/postgres.rb', line 55

def get_tables_by_schema_postgres(client, schema_names)
  all_tables = schema_names.flat_map do |schema|
    sql = <<~SQL
      SELECT table_name, table_schema 
      FROM information_schema.tables 
      WHERE table_schema = '#{schema}'
      AND table_type = 'BASE TABLE'
    SQL
    
    results = run_query_postgres(sql, client)
    results[:rows].map do |row|
      {
        tableName: row['table_name'],
        schemaName: row['table_schema']
      }
    end
  end

  all_tables
end

.run_query_postgres(sql, client) ⇒ Object 



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# File 'lib/db/postgres.rb', line 27

def run_query_postgres(sql, client)
  result = client.exec(sql)
  
  fields = result.fields.map do |field|
    {
      name: field,
      dataTypeID: result.ftype(result.fields.index(field))
    }
  end

  {
    fields: fields,
    rows: result.values.map { |row| result.fields.zip(row).to_h }
  }
end