lodel2_mirror/DataSource/MySQL/common_utils.py

# -*- coding: utf8 -*-

from Lodel.settings import Settings

## @brief Manages the accesses to a MySQL datasource
class MySQL(object):

    relations_table_name = 'relation'
    relations_pkname = 'id_relation'
    relations_field_nature = 'nature'
    field_lodel_id = 'lodel_id'
    class_table_prefix = 'class_'
    objects_table_name = 'object'
    connections = Settings.get("datasource")
    ## @brief indicates if we want ON DELETE CASCADE on foreign keys
    # @todo implementation in migration handler
    fk_on_delete_cascade = False
    ## @brief Lodel_id for the hierachy root
    leroot_lodel_id = 0

    @staticmethod
    ## @brief Exec a query
    # @param query str : SQL query
    def query(connection, query):
        with connection as cur:
            try:
                cur.execute(query)
            except Exception as err:
                raise err
            return cur

    @classmethod
    ## @brief gets the table name from class name
    # @param class_name str
    # @return str
    def get_table_name_from_class(cls, class_name):
        return (class_name if cls.class_table_prefix in class_name else "%s%s" % (cls.class_table_prefix, class_name)).lower()

    @classmethod
    ## @brief gets the table name given a class, a type and a field names
    # @param class_name str
    # @param type_name str
    # @param field_name str
    # @return str
    def get_r2t2table_name(cls, class_name, type_name):
        return ("r2t_%s_%s" % (class_name, type_name)).lower()

    @classmethod
    ## @brief gets the fk name between two tables
    # @param src_table_name str
    # @param dst_table_name str
    # @return str
    def get_fk_name(cls, src_table_name, dst_table_name):
        return "fk_%s_%s" % (src_table_name, dst_table_name)

    @classmethod
    ## @brief Identifier escaping
    # @param idname str : An SQL identifier
    def escape_idname(cls, idname):
        if '`' in idname:
            raise ValueError("Invalid name : '%s'" % idname)
        return '`%s`' % idname

    @classmethod
    ## @brief Given a fieldtype, returns a MySQL type specifier
    # @param emfieldType EmFieldType : A fieldtype
    # @return str
    def get_type_spec_from_fieldtype(cls, emfieldtype):

        ftype = emfieldtype.ftype

        if ftype == 'char' or ftype == 'str':
            res = "VARCHAR(%d)" % emfieldtype.max_length
        elif ftype == 'text':
            res = 'TEXT'
        elif ftype == 'datetime':
            res = "DATETIME"
            # client side workaround for only one column with CURRENT_TIMESTAMP : giving NULL to timestamp that don't allows NULL
            # cf. https://dev.mysql.com/doc/refman/5.0/en/timestamp-initialization.html#idm139961275230400
            # The solution for the migration handler is to create triggers :
            # CREATE TRIGGER trigger_name BEFORE INSERT ON `my_super_table`
            # FOR EACH ROW SET NEW.my_date_column = NOW();
            # and
            # CREATE TRIGGER trigger_name BEFORE UPDATE ON
        elif ftype == 'bool':
            res = "BOOL"
        elif ftype == 'int':
            res = "INT"
        elif ftype == 'rel2type':
            res = "INT"
        else:
            raise ValueError("Unsupported fieldtype ftype : %s" % ftype)

        return res

    ## Brief add table prefix to a column name
    # @param name string: column name to prefix
    # @param prefixes dict(prefix:list(name,))
    # @return prefixed_name string: the name prefixed
    # find the same name in some list of names, prepend the key of the dict to the name
    @staticmethod
    def find_prefix(name, prefixes):
        for prefix, names in prefixes:
            if name in names:
                return MySQL.column_prefix(prefix, name)
        return name

    ## prefix a column name with the table name
    @staticmethod
    def column_prefix(table, column):
        return '%s.%s' % (table, column)