MongoDB CSV file Import and Export

1. Export to CSV file:

　　

2. Import from CSV:

　　

data is exported through CSV export, there is a very hidden problem , you need to note when writing code:

Pilot into one data:

　　　　

Where Price is a double type:

　　　　

Then I export the record to demo.csv and delete the record from the database, and then import the record from Demo.csv:

　　　　

Then look at this record in the database:

　　　　

found that the price value of the original double type 66.000000 automatically became the Int32 type 66.

　　When the problem arises , you will not get a value if you still use Bson_iter_double (&iter) to fetch the Price field:

　　　　

The value can only be taken with Bson_iter_int32 (&iter):

　　　　

　　so get the conclusion :

When you need to fetch a field of type float (or double) in your data, the code should be written as follows:

　　　　

Avoid issues where the field values are not taken after the data has been exported to CSV and then imported from CSV.

MongoDB CSV file Import and Export