Re. TOOLS-67: mongoimport csv/tsv with specified types
For 3.4.0 release.

Most of the documentation that needs to be added will be regarding the last section in the following changeling (on the typed field input format):

overview of changes:

• two new command line options:
  • 'columnsHaveTypes', boolean whether the field types are to be specified;
  • 'parseGrace', how to handle type coercion failures (one of skipField,
    skipRow, stop, autoCast). The skipRow option sends failed rows to
    standard output.
• changed behavior:
  • if 'columnsHaveTypes' is set, then wherever column names are specified,
    the types will also be specified. If 'headerLine' is set, this refers
    to the first line of the input source. If 'fieldFile' is set, this
    refers to the file with the field names. If neither of these two
    options is set, this refers to the string given in the 'fields'
    option.
  • (behavior is unchanged if 'columnsHaveTypes' is not set)
• new typed field input format (from wherever column names are specified):
  '<COLNAME>.<TYPE>(<ARG>)'
  • <TYPE> is one of: auto, binary, bool, date, date_go, date_ms,
    date_oracle, double, int32, int64, string. The 'date' type is an alias
    for 'date_go'.
  • <ARG> depends on the type. It can only be non-empty for the binary,
    date, date_go, date_ms, and date_oracle types.
    • Three characters, if used within the argument, must be
      backslash-escaped: '(', ')', and '\'.
    • For the 'binary' type, the argument is the encoding and must be one of
      base64, base32, or hex. The base64 and base32 variants correspond to
      the standard defined in RFC 4648.
    • For any of the 'date' types, the argument is a datetime layout string
      corresponding to the following:
      • 'date' aliases to 'date_go'
      • 'date_go' layouts correspond to the Golang time.Parse function
      • 'date_ms' layouts correspond to the Microsoft SQL Server FORMAT function
      • 'date_oracle' layouts correspond to the Oracle Database TO_DATE function
  • examples:
    • 'zipcode.string()'
    • 'followerCount.int32()'
    • 'user thumbnail.binary(base64)'
    • 'verified.boolean()'
    • 'misc.auto()'
    • 'created.date_ms(MM/dd/yyyy hh:mm:ss)'