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Selection method added to database

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This commit is contained in:
Doug Blank 2015-12-30 14:03:46 -05:00
parent 41f9e3cccc
commit 0bfee44e9b
1 changed files with 106 additions and 2 deletions
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108
gramps/gen/db/base.py
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@ -30,19 +30,26 @@ from this class.
# Python libraries
#
#-------------------------------------------------------------------------
from ..const import GRAMPS_LOCALE as glocale
_ = glocale.translation.gettext
import re
#-------------------------------------------------------------------------
#
# Gramps libraries
#
#-------------------------------------------------------------------------
from ..const import GRAMPS_LOCALE as glocale
_ = glocale.translation.gettext
from ..lib.childreftype import ChildRefType
from ..lib.childref import ChildRef
from .txn import DbTxn
from .exceptions import DbTransactionCancel
#-------------------------------------------------------------------------
#
# Gramps libraries
#
#-------------------------------------------------------------------------
class DbReadBase(object):
"""
Gramps database object. This object is a base class for all
@ -1868,3 +1875,100 @@ class DbWriteBase(DbReadBase):
self.remove_family(instance.handle, transaction)
else:
raise ValueError("invalid instance type: %s" % instance.__class__.__name__)
def select(self, table, fields=None, sort=False, start=0, limit=50,
filter=None):
"""
Default implementation of a select for those databases
that don't support SQL. Yields data row by row.
table - Person, Family, etc.
fields - used by object.get_field()
sort - use sort order (argument to DB.get_X_handles)
start - position to start
limit - count to get; -1 for all
filter - {field: (SQL string_operator, value), }
handles all SQL except for NOT expression, eg NOT x = y
"""
def hash_name(name):
"""
Used in filter to eval expressions involving selected
data.
"""
return (name
.replace(".", "_D_")
.replace("(", "_P_")
.replace(")", "_P_"))
# Fields is None or list, maybe containing "*":
if fields is None:
fields = ["*"]
elif not isinstance(fields, (list, tuple)):
raise Exception("fields must be a list/tuple of field names")
if "*" in fields:
fields.remove("*")
fields.extend(self._tables[table]["class_func"].get_schema().keys())
# Get iterator of handles, possibly sorted by name, etc.:
if sort:
data = self._tables[table]["handles_func"](sort_handles=True)
else:
data = self._tables[table]["handles_func"]()
position = 0
selected = 0
for handle in data:
if position < start:
pass # skip it
else:
item = self._tables[table]["handle_func"](handle)
row = []
env = {}
for field in fields:
value = item.get_field(field)
row.append(value)
if filter:
env[hash_name(field)] = value
if filter:
matched = True
for name, (op, value) in filter.items():
v = eval(hash_name(name), env)
if op == "=":
matched = v == value
elif op == ">":
matched = v > value
elif op == ">=":
matched = v >= value
elif op == "<":
matched = v < value
elif op == "<=":
matched = v <= value
elif op == "IN":
matched = v in value
elif op == "IS":
matched = v is value
elif op == "IS NOT":
matched = v is not value
elif op == "IS NULL":
matched = v is None
elif op == "IS NOT NULL":
matched = v is not None
elif op == "BETWEEN":
matched = value[0] <= v <= value[1]
elif op in ["<>", "!="]:
matched = v != value
elif op == "LIKE":
value = value.replace("%", "(.*)").replace("_", ".")
matched = re.match(value, v)
else:
raise Exception("invalid select operator: '%s'" % op)
if not matched:
break
if matched:
selected += 1
yield row
else:
continue
else:
selected += 1
yield row
position += 1
if selected == limit:
break