Save cursor field on a persistent storage

Connector Development
1

Hello,

I am building a connector that is pulling data from an API. I am filtering data for a given date range. I read and understand that cursor with incremental sync can help you to pull data from the last time you run the synchronization between source and destination.
I am pulling data for today on an hourly basis.

Let’s say now the connection was down for some days, and it didn’t work. Then I put it up, and I want it to sync data from the last time a record was put in the destination table.

How can I achieve this with the cursor?

  • Is it possible pull the cursor value from the destination table?
  • Is there a way, after each sync, I can save the cursor value in a permanent storage, let’s say, the Postgres database? And pull it from there?

Some code for the context

Getter and setter for my cursor:

@property
    def state(self) -> Mapping[str, Any]:
        if getattr(self, '_cursor_value', None):
            return {self.cursor_field: self._cursor_value}
        else:
            return {self.cursor_field: datetime.today().strftime('%Y-%m-%d')} # THIS IS THE DATE I WOULD LIKE TO SAVE ON A PERSISTENT STORAGE

    @property
    def cursor_field(self) -> str:
        """
        Name of the field in the API response body used as cursor.
        """
        return "date"
    
    @state.setter
    def state(self, value: Mapping[str, Any]):
        self._cursor_value = value[self.cursor_field]

This is how I am updating the cursor.

for row in reader:
    item = self.generate_item(row)
    # this section deals with the cursor, to be revisited
    current_cursor_value = pendulum_parse(self.state.get(self.cursor_field))
    upcoming_cursor_value = pendulum_parse(getattr(item, self.cursor_field).strftime('%Y-%m-%d'))
    cursor_value = (max(upcoming_cursor_value, current_cursor_value)).to_date_string()
    max_cursor_value = {self.cursor_field: cursor_value}
    self.state = max_cursor_value
    yield item.dict()

Any pointer on how I can achieve this will be welcome.

2

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3

Hey thanks for reaching out to us. Currently, the cursor value i.e state is handled through persistent storage. We save the state in the database and when we next run the sync we get the state from there and run the sync

4

Thank you for your answer, @harshith.

So basically, if that is the case, it means my connector is working well.

5

Hey,

I am coming back to this question.

Would you advise the best way to pull the state from the persistent storage?

I am using this code here, but it seems to not work.

@property
    def state(self) -> Mapping[str, Any]:
        if getattr(self, '_cursor_value', None):
            return {self.cursor_field: self._cursor_value}
        else:
            return {self.cursor_field: self.start_date.strftime('%Y-%m-%d')}
6

Hello Espoir Murhabazi, it’s been a while without an update from us. Are you still having problems or did you find a solution?