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Conditional put was causing "condition failed" error, even when the condition was met #517

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There are two kind of conditional puts in dynamodb
1. If attribute exists or not. Is is needed to be represented in the request as {"attr_name" : {"Exist" : } }
2. We can also check the value of the attribute and only change the data if that condition is met. e.g
for Item.put if expected_value is {"attr_name": "old_attr"}
Then "put: will only be successful if the "attr_name" attribute in the dynamodb was previously has value "old_attr"

The correct format for the request should be {"attr_name" : {"Value" : {"S" : "old_attr"} } }
but we were always sending it as {"attr_name" : {"S" : "old_attr"} } . hence the Item.put was always failing.

Nishant The conditional put requires attribute value to be inthe form {'Value…
…': dynamize_valu} we were directly passing dynamize_value.

I don't suppose we could talk you into providing a unit test for this that shows the currently failing behavior? This would be invaluable in making sure we don't break this again.

@garnaat garnaat closed this in fd893b3
@msabramo msabramo pushed a commit to msabramo/boto that referenced this pull request
@garnaat garnaat Fix handling of Expected parameter. Closes #517. d144c7d
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Commits on Jan 25, 2012
  1. The conditional put requires attribute value to be inthe form {'Value…

    Nishant committed
    …': dynamize_valu} we were directly passing dynamize_value.
Showing with 1 addition and 1 deletion.
  1. 0 boto/dynamodb/
  2. +1 −1 boto/dynamodb/
0 boto/dynamodb/ 100644 → 100755
File mode changed.
2 boto/dynamodb/ 100644 → 100755
@@ -118,7 +118,7 @@ def dynamize_expected_value(self, expected_value):
elif attr_value is False:
attr_value = {'Exists': False}
- attr_value = self.dynamize_value(expected_value[attr_name])
+ attr_value = {'Value' : self.dynamize_value(expected_value[attr_name])}
d[attr_name] = attr_value
return d
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