BigQuery adding unnecessary decimals to defined STRING - r

Question

I have defined a schema in BigQuery as such:
+------------------+----------+----------+
| name | type | mode |
+------------------+----------+----------+
| warehouse | INTEGER | NULLABLE |
| transaction_date | DATETIME | NULLABLE |
| style | STRING | NULLABLE |
| piece | STRING | NULLABLE |
| fabric_1 | STRING | NULLABLE |
| fabric_2 | STRING | NULLABLE |
| serial | STRING | NULLABLE |
| customer_po | STRING | NULLABLE |
| order_number | STRING | NULLABLE |
+------------------+----------+----------+
The two fields I'm focusing on are serial and order_number, which when previewed in R, look like this:
+-----------+------------------+--------+-------+-----------+----------+------------+--------------+--------------+
| warehouse | transaction_date | style | piece | fabric_1 | fabric_2 | serial | customer_po | order_number |
+-----------+------------------+--------+-------+-----------+----------+------------+--------------+--------------+
| 80 | 4/3/19 | K28300 | ARMH | ALL CHAR | NA | 8040418253 | 1486838165 | 464374 |
| 80 | 4/3/19 | K28300 | ARMH | ALL CHAR | NA | 9040542252 | 1485798731-P | 464069 |
| 80 | 4/3/19 | K28300 | ARMH | ELEG NAVY | NA | 8040355550 | 1486826068 | 464369 |
| 80 | 4/3/19 | K28300 | ARMH | ELEG NAVY | NA | 8040532364 | 1485366411-R | 464071 |
+-----------+------------------+--------+-------+-----------+----------+------------+--------------+--------------+
Within R, those two fields appear to be read as characters in the dataframe I'm uploading, which is what I'm looking for. Yet when I push the data to BigQuery, those two fields end up like such:
+-----------+------------------+--------+-------+-----------+----------+------------+--------------+--------------+
| warehouse | transaction_date | style | piece | fabric_1 | fabric_2 | serial | customer_po | order_number |
+-----------+------------------+--------+-------+-----------+----------+------------+--------------+--------------+
| 80 | 4/3/19 | K28300 | ARMH | ALL CHAR | NA | 8040418253.0 | 1486838165 | 464374.0 |
| 80 | 4/3/19 | K28300 | ARMH | ALL CHAR | NA | 9040542252.0 | 1485798731-P | 464069.0 |
| 80 | 4/3/19 | K28300 | ARMH | ELEG NAVY | NA | 8040355550.0 | 1486826068 | 464369.0 |
| 80 | 4/3/19 | K28300 | ARMH | ELEG NAVY | NA | 8040532364.0 | 1485366411-R | 464071.0 |
+-----------+------------------+--------+-------+-----------+----------+------------+--------------+--------------+
Why is this happening, and how can I change it? For reference, my code to upload it:
bqr_upload_data(projectId = "project-test",
datasetId = "orders",
tableId = "daily_orders",
upload_data = df_daily_orders,
maxBadRecords = 1000,
overwrite = TRUE)

Answer 1

The upload from R looks at the class of the column to decide which is the best schema for BigQuery. Try changing the class of the data frame column to string to avoid it changing it to float as what looks like is happening via something like
as.character(df$column)

Answer 2

Now I'm not completely sure in my answer, as I am still a beginner, but it may help you. I would add this as a comment, but I don't have enough reputation yet.
If I understood properly, you are actually doing an implicit casting - from a numerical value to a string value and BigQuery is catching the decimal point as to be sure that it's properly catching the whole value
Check here BigQuery's conversion rules - second table, FLOAT64 to String.
In your place and depending on what you need to do with the table - I would:
Recreate the table, but change the schema for serial and order_number columns to an integer type
or
Try to update the already created table with an update query - and modifying the '.0' at the end of every string value