def _update_field_in_table_if_exists(
self, table: Table, field_value: t.Any, field_name: str
) -> bool:
"""
Only write the field for object in table if the objects with matchig PK and SK already exist
(also updates updated_at).
Returns true if object existed and therefore update was successful otherwise false.
"""
try:
table.update_item(
Key={
"PK": self.get_dynamodb_signal_key(
self.SIGNAL_SOURCE_SHORTCODE, self.signal_id
),
"SK": self.get_sort_key(self.privacy_group_id),
},
# service_resource.Table.update_item's ConditionExpression params is not typed to use its own objects here...
ConditionExpression=And(Attr("PK").exists(), Attr("SK").exists()), # type: ignore
ExpressionAttributeValues={
":f": field_value,
":u": self.updated_at.isoformat(),
},
ExpressionAttributeNames={
"#F": field_name,
"#U": "UpdatedAt",
},
UpdateExpression="SET #F = :f, #U = :u",
)
except ClientError as e:
if e.response["Error"]["Code"] != "ConditionalCheckFailedException":
raise e
return False
return True
def write_to_table(self, table: Table):
"""
Write operations for this object need to be special cased (to avoid overwritting)
Therefore we do not implement `to_dynamodb_item` however basically the body of that
method is used in this class's impl of `write_to_table_if_not_found`
"""
# put_item does not support UpdateExpression
table.update_item(
Key={
"PK": self.get_dynamodb_content_key(self.content_id),
"SK": self.get_dynamodb_content_type_key(),
},
# If ContentRef exists it needs to match or BAD THING(tm) can happen...
ConditionExpression=Or(
Attr("ContentRef").not_exists(),
Attr("ContentRef").eq(self.content_ref)), # type: ignore
# Unfortunately while prod is happy with this on multiple lines pytest breaks...
UpdateExpression=
"""SET ContentType = :ct, ContentRef = :cr, ContentRefType = :crt, SubmissionTimes = list_append(if_not_exists(SubmissionTimes, :empty_list), :s), CreatedAt = if_not_exists(CreatedAt, :c), UpdatedAt = :u ADD AdditionalFields :af""",
ExpressionAttributeValues={
":ct": self.content_type.get_name(),
":cr": self.content_ref,
":crt": self.content_ref_type.value,
":af": self.additional_fields if self.additional_fields else
{self.ADDITIONAL_FIELDS_PLACE_HOLDER},
":s": [s.isoformat() for s in self.submission_times],
":c": self.created_at.isoformat(),
":u": self.updated_at.isoformat(),
":empty_list": [],
},
)
def dec(self, table: Table, by=1):
"""
Increment count. Default by 1, unless specified.
"""
table.update_item(
Key={"PK": self.get_pkey(), "SK": self.get_skey()},
UpdateExpression="SET CurrentCount = if_not_exists(CurrentCount, :zero) - :by",
ExpressionAttributeValues={":by": by, ":zero": 0},
)
def increment_counts(cls, table: Table, counts: t.Dict[str, int]):
for pg in counts:
table.update_item(
# Couldn't find a way to do update_item in batch. Can optimize
# if found.
Key={
"PK": cls._get_pkey(),
"SK": cls._get_skey(pg)
},
UpdateExpression=
"SET WriteCount = if_not_exists(WriteCount, :zero) + :by",
ExpressionAttributeValues={
":by": counts[pg],
":zero": 0
},
)
def write_to_table(self, table: Table):
"""
Write operations for this object need to be special cased (to avoid overwritting)
Therefore we do not implement `to_dynamodb_item`
If you're curious it would ~look like this:
def to_dynamodb_item(self) -> dict:
return {
"PK": self.get_dynamodb_content_key(self.content_id),
"SK": self.get_dynamodb_content_type_key(self.content_type),
"ContentRef": self.content_ref,
"ContentRefType": self.content_ref_type,
"AdditionalFields": self.additional_fields,
"SubmissionTimes": [s.isoformat() for s in self.submission_times],
"CreatedOn": self.created_at.isoformat(),
"UpdatedAt": self.updated_at.isoformat(),
}
"""
# put_item does not support UpdateExpression
table.update_item(
Key={
"PK": self.get_dynamodb_content_key(self.content_id),
"SK": self.get_dynamodb_content_type_key(self.content_type),
},
# If ContentRef exists it needs to match or BAD THING(tm) can happen...
ConditionExpression=Or(
Attr("ContentRef").not_exists(),
Attr("ContentRef").eq(self.content_ref)), # type: ignore
# Unfortunately while prod is happy with this on multiple lines pytest breaks...
UpdateExpression=
"""SET ContentRef = :cr, ContentRefType = :crt, SubmissionTimes = list_append(if_not_exists(SubmissionTimes, :empty_list), :s), CreatedAt = if_not_exists(CreatedAt, :c), UpdatedAt = :u ADD AdditionalFields :af""",
ExpressionAttributeValues={
":cr": self.content_ref,
":crt": self.content_ref_type.value,
":af": self.additional_fields
if self.additional_fields else {"Placeholder"},
":s": [s.isoformat() for s in self.submission_times],
":c": self.created_at.isoformat(),
":u": self.updated_at.isoformat(),
":empty_list": [],
},
)
def update_item(table: Table, wizard: str, update_expression: str,
attributes: dict, return_values: Any) -> Union[Any, bool]:
try:
db_response = table.update_item(Key={'username': wizard},
UpdateExpression=update_expression,
ExpressionAttributeValues=attributes,
ReturnValues=return_values)
return db_response
except Exception as e:
print("Something went wrong: ", e)
return False
def get_unique(cls, table: Table, signal_type: t.Type[SignalType],
signal_value: str) -> "BankedSignalEntry":
"""
Write to the table if PK / SK does not exist. In either case (exists,
not exists), return the current unique entry.
This is a special use-case for BankedSignalEntry. If this is useful to
other models, we can move it to a mixin or to dynamodb item. If trying
to generify, note how the update_item query needs a custom update query
based on what you are trying to write. Generifying may be harder than it
seems.
"""
result = table.update_item(
Key={
"PK": cls.get_pk(signal_type),
"SK": cls.get_sk(signal_value),
},
UpdateExpression=
"SET SignalId = if_not_exists(SignalId, :signal_id), SignalType = :signal_type, SignalValue = :signal_value",
ExpressionAttributeValues={
# Note we are generating a new uuid even though we don't always
# expect it to get written. AFAIK, uuids are inexhaustible, and
# generation performance is good enough to not worry about it.
":signal_id": str(uuid.uuid4()),
":signal_type": signal_type.get_name(),
":signal_value": signal_value,
},
ReturnValues="ALL_NEW",
).get("Attributes")
assert result is not None
return BankedSignalEntry(
signal_type=signal_type,
signal_value=t.cast(str, result["SignalValue"]),
signal_id=t.cast(str, result["SignalId"]),
)
