mongoimport: set type for all fields when importing CSV - mongodb

Question

I have multiple problems with importing a CSV with mongoimport that has a headerline.
Following is the case:
I have a big CSV file with the names of the fields in the first line.
I know you can set this line to use as field names with: --headerline.
I want all field types to be strings, but mongoimport sets the types automatically to what it looks like.
IDs such as 0001 will be turn into 1, which can have bad side effects.
Unfortunately, there is (as far as i know) no way of setting them as string with a single command, but by naming each field and setting it type with
--columnsHaveTypes --fields "name.string(), ... "
When I did that, the next problem appeared.
The headerline (with all field names) got imported as values in a separate document.
So basically, my questions are:
Is there a way of setting all field types as string using the --headerline command ?
Alternative, is there a way to ignore the first line ?

Answer 1

I had this problem when uploading 41 million record CSV file into mongodb.
./mongoimport -d testdb -c testcollection --type csv --columnsHaveTypes -f
"RECEIVEDDATE.date(2006-01-02 15:04:05)" --file location/test.csv
As above we have a command to upload file with data types called '-f' or '--fields' but when we use this command to the file that contain header line, mondodb upload first row as well i.e header lines row then its leads error 'cannot convert to datatype' or upload column names also as data set.
Unfortunately we cannot use '--headerline' command instead of '--fields'.
Here the solutions that I found for this problem.
1)Remove header column and upload using '--fields' command as above command. if you re use linux environment you can use below command to remove first row of the huge file i.e header line.it took 2-3 mints for me.(depending on the machine performance)
sed -i -e "1d" location/test.csv
2)upload the file using '--headerline' command then mongodb uploads the file with its default identified data types.Then open mongodb shell command use testdb then run javascript command that get each record and change it into specific data types.But if you have huge file this will takes time.
found this solution from stackoverflow
db.testcollection.find().forEach( function (x) {
x.RECEIVEDDATE = new Date(x.RECEIVEDDATE ); db.testcollection .save(x);});
If you wanna remove the unnecessary rows that not fit to data type use below command.
mongodb document
'--parseGrace skipRow'

Answer 2

I found a solution, that I am comfortable with
Basically, I wanted to use mongoimport within my Clojure Code to import a CSV file in the DB and do a lot of stuff with it automatically. Due to the above mentioned problems I had to find a workaround, to delete this wrong document.
I did following to "solve" this problem:
To set the types as I wanted, I wrote a function to read the first line, put it in a vector and then used String concatenation to set these as fields.
Turning this: id,name,age,hometown,street
into this: id.string(),name.string(),age.string() etc
Then I used the values from the vector to identify the document with
{ name : "name"
age : "age"
etc : "etc" }
and then deleted it with a simple remving.find() command.
Hope this helps any dealing with the same kind of problem.

Answer 3

https://docs.mongodb.com/manual/reference/program/mongoimport/#example-csv-import-types reads:
MongoDB 3.4 added support for specifying field types. Specify field names and types in the form .() using --fields, --fieldFile, or --headerline.
so your first line within the csv file should have names with types. e.g.:
name.string(), ...
and the mongoimport parameters
--columnsHaveTypes --headerline --file <filename.csv>
As to the question of how to remove the first line, you can employ pipes. mongoimport reads from STDIN if no --file option passed. E.g.:
tail -n+2 <filename.csv> | mongoimport --columnsHaveTypes --fields "name.string(), ... "