✨ guard against integer precision loss. https://github.com/pyexcel/pyexcel-ods/issues/30

pyexcel_io/constants.py

@@ -59,3 +59,5 @@ SEPARATOR_FORMATTER = "---%s---" % DEFAULT_NAME + "%s"
 SEPARATOR_MATCHER = "---%s:(.*)---" % DEFAULT_NAME
 DEFAULT_CSV_STREAM_FILE_FORMATTER = "---%s:" % DEFAULT_NAME + "%s---%s"
 DEFAULT_CSV_NEWLINE = "\r\n"
+
+MAX_INTEGER = 999999999999999

pyexcel_io/exceptions.py

@@ -25,3 +25,32 @@ class UpgradePlugin(Exception):
     """raised when a known plugin is not compatible"""
 
     pass
+
+
+class IntegerAccuracyLossError(Exception):
+    """
+    When an interger is greater than 999999999999999, ods loses its accuracy.
+
+    from pyexcel import Sheet, get_sheet
+    s = Sheet()
+    s[0,0] = 999999999999999  # 15 '9's
+    print(s)
+    s.save_as('abc.ods')
+    b=get_sheet(file_name='abc.ods')
+    b[0,0] == s[0,0]
+
+    s = Sheet()
+    s[0,0] = 9999999999999999 # 16 '9's
+    print(s)
+    s.save_as('abc.ods')
+    b=get_sheet(file_name='abc.ods')
+    b[0,0] != s[0,0]
+    """
+    def __init__(self, message):
+        custom_message = (
+            message + '\n' +
+            "In order to keep its accuracy, please save as string. Then " +
+            "convert to int, long or float after the value will be read back"
+        )
+
+        super(IntegerAccuracyLossError, self).__init__(custom_message)

pyexcel_io/service.py

@@ -12,6 +12,8 @@ import math
 import datetime
 
 from pyexcel_io._compact import PY2
+from pyexcel_io import constants
+from pyexcel_io import exceptions
 
 
 def has_no_digits_in_float(value):
@@ -97,10 +99,16 @@ def detect_int_value(cell_text, pep_0515_off=True):
 
 def float_value(value):
     """convert a value to float"""
+    if value > constants.MAX_INTEGER:
+        raise exceptions.IntegerAccuracyLossError("%s is too big" % value)
     ret = float(value)
     return ret
 
 
+def throw_exception(value):
+    raise exceptions.IntegerAccuracyLossError("%s is too big" % value)
+
+
 def date_value(value):
     """convert to data value accroding ods specification"""
     ret = "invalid"
@@ -168,7 +176,6 @@ ODS_FORMAT_CONVERSION = {
 
 ODS_WRITE_FORMAT_COVERSION = {
     float: "float",
-    int: "float",
     str: "string",
     datetime.date: "date",
     datetime.time: "time",
@@ -178,7 +185,8 @@ ODS_WRITE_FORMAT_COVERSION = {
 
 if PY2:
     ODS_WRITE_FORMAT_COVERSION[unicode] = "string"
-    ODS_WRITE_FORMAT_COVERSION[long] = "float"
+    ODS_WRITE_FORMAT_COVERSION[long] = "throw_exception"
+
 
 VALUE_CONVERTERS = {
     "float": float_value,
@@ -220,6 +228,7 @@ ODS_VALUE_CONVERTERS = {
     "time": ods_time_value,
     "boolean": ods_bool_value,
     "timedelta": ods_timedelta_value,
+    "throw_exception": throw_exception
 }
 
 

tests/test_service.py

@@ -3,7 +3,10 @@ from pyexcel_io.service import date_value, time_value
 from pyexcel_io.service import detect_int_value
 from pyexcel_io.service import detect_float_value
 from pyexcel_io.service import ODS_WRITE_FORMAT_COVERSION
+from pyexcel_io.service import float_value
+from pyexcel_io.service import throw_exception
 from pyexcel_io._compact import PY2
+from pyexcel_io.exceptions import IntegerAccuracyLossError
 from nose import SkipTest
 
 
@@ -100,3 +103,13 @@ def test_ods_write_format_conversion():
         eq_('float', expected)
     else:
         raise SkipTest
+
+
+@raises(IntegerAccuracyLossError)
+def test_big_int_value():
+    float_value(1000000000000000)
+
+
+@raises(IntegerAccuracyLossError)
+def test_throw_exception():
+    throw_exception(1000000000000000)