CSV Module

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This XQuery Module contains a single function to parse CSV input. CSV (comma-separated values) is a popular representation for tabular data, exported e. g. from Excel.

Contents

Conventions

All functions in this module are assigned to the http://basex.org/modules/csv namespace, which is statically bound to the csv prefix.
All errors are assigned to the http://basex.org/errors namespace, which is statically bound to the bxerr prefix.

Conversion

XML: Direct, Attributes

CSV is converted to XML as follows:

Map

If format is set to map, the CSV data will be converted to an XQuery map:

A little advice: in the Database Creation dialog of the GUI, if you select CSV Parsing and switch to the Parsing tab, you can see the effects of some of the conversion options.

Options

Updated with Version 8.6: improved Excel compatibility

In the following table, all available options are listed. The Excel column indicates what are the preferred options for data that is to be imported, or has been exported from Excel.

Option Description Allowed Default Excel
separator Defines the character which separates the values of a single record. comma, semicolon, colon, tab, space or a single character comma semicolon
header Indicates if the first line of the parsed or serialized CSV data is a table header. yes, no no
format Specifies the format of the XML data. The format is only relevant if the header option is activated:
  • With direct conversion, field names are represented as element names
  • With attributes conversion, field names are stored in name attributes
  • With map conversion, the input is converted to an XQuery map
direct, attributes, map direct
lax Specifies if a lax approach is used to convert QNames to JSON names. yes, no yes no
quotes Specifies how quotes are parsed:
  • Parsing: If the option is enabled, quotes at the start and end of a value will be treated as control characters. Separators and newlines within the quotes will be adopted without change.
  • Serialization: If the option is enabled, the value will be wrapped with quotes. A quote character in the value will be encoded according to the rules of the backslashes option.
yes, no yes yes
backslashes Specifies how quotes and other characters are escaped:
  • Parsing: If the option is enabled, \r, n and \t will be replaced with the corresponding control characters. All other escaped characters will be adopted as literals (e.g.: \""). If the option is disabled, two consecutive quotes will be replaced with a single quote (unless quotes is enabled and the quote is the first or last character of a value).
  • Serialization: If the option is enabled, \r, n, \t, " and the separator character will be encoded with a backslash. If the option is disabled, quotes will be duplicated.
yes, no no no

Functions

csv:parse

Signatures csv:parse($input as xs:string) as document-node(element(csv))
csv:parse($input as xs:string, $options as map(xs:string, item())) as item()
Summary Converts the CSV data specified by $input to an XML document or a map. The $options argument can be used to control the way the input is converted.
Errors BXCS0001: the input cannot be parsed.

csv:serialize

Signatures csv:serialize($input as node()) as xs:string
csv:serialize($input as node(), $options as map(xs:string, item())) as xs:string
Summary Serializes the node specified by $input as CSV data, and returns the result as xs:string. Items can also be serialized as JSON if the Serialization Parameter method is set to csv.
The $options argument can be used to control the way the input is serialized.
Errors BXCS0002: the input cannot be serialized.

Examples

Example 1: Converts CSV data to XML, interpreting the first row as table header:

Input addressbook.csv:

Name,First Name,Address,City
Huber,Sepp,Hauptstraße 13,93547 Hintertupfing

Query:

let $text := file:read-text('addressbook.csv')
return csv:parse($text, map { 'header': true() })

Result:

<csv>
  <record>
    <Name>Huber</Name>
    <First_Name>Sepp</First_Name>
    <Address>Hauptstraße 13</Address>
    <City>93547 Hintertupfing</City>
  </record>
</csv>

Example 2: Converts some CSV data to XML and back, and checks if the input and output are equal. The expected result is true:

Query:

let $options := map { 'lax': false() }
let $input := file:read-text('some-data.csv')
let $output := $input => csv:parse($options) => csv:serialize($options)
return $input eq $output

Example 3: Converts CSV data to an XQuery map item and serializes its contents:

Query:

let $text := "Name;City" || out:nl() || "John;Newton" || out:nl() || "Jack;Oldtown"
let $options := map {
  'separator': ';',
  'format'   : 'map',
  'header'   : true()
}
return csv:parse($text, $options)

Result:

map {
  1: map {
    "City": "Newton",
    "Name": "John"
  },
  2: map {
    "City": "Oldtown",
    "Name": "Jack"
  }
}

Errors

Code Description
BXCS0001 The input cannot be parsed.
BXCS0002 The node cannot be serialized.

Changelog

Version 8.6
Version 8.0
Version 7.8

The module was introduced with Version 7.7.2.

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