Difference between revisions of "CSV Module"
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==Options== | ==Options== | ||
− | + | {{Mark|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. | ||
{| class="wikitable sortable" width="100%" | {| class="wikitable sortable" width="100%" | ||
Line 40: | Line 42: | ||
! Allowed | ! Allowed | ||
! Default | ! Default | ||
+ | ! Excel | ||
|- valign="top" | |- valign="top" | ||
| {{Code|separator}} | | {{Code|separator}} | ||
− | | Defines the character which separates the | + | | Defines the character which separates the values of a single record. |
| {{Code|comma}}, {{Code|semicolon}}, {{Code|colon}}, {{Code|tab}}, {{Code|space}} or a ''single character'' | | {{Code|comma}}, {{Code|semicolon}}, {{Code|colon}}, {{Code|tab}}, {{Code|space}} or a ''single character'' | ||
| {{Code|comma}} | | {{Code|comma}} | ||
+ | | {{Code|semicolon}} | ||
|- valign="top" | |- valign="top" | ||
| {{Code|header}} | | {{Code|header}} | ||
Line 50: | Line 54: | ||
| {{Code|yes}}, {{Code|no}} | | {{Code|yes}}, {{Code|no}} | ||
| {{Code|no}} | | {{Code|no}} | ||
+ | | | ||
|- valign="top" | |- valign="top" | ||
| {{Code|format}} | | {{Code|format}} | ||
Line 58: | Line 63: | ||
| {{Code|direct}}, {{Code|attributes}}, {{Code|map}} | | {{Code|direct}}, {{Code|attributes}}, {{Code|map}} | ||
| {{Code|direct}} | | {{Code|direct}} | ||
+ | | | ||
|- valign="top" | |- valign="top" | ||
| {{Code|lax}} | | {{Code|lax}} | ||
Line 63: | Line 69: | ||
| {{Code|yes}}, {{Code|no}} | | {{Code|yes}}, {{Code|no}} | ||
| {{Code|yes}} | | {{Code|yes}} | ||
+ | | {{Code|no}} | ||
|- valign="top" | |- valign="top" | ||
| {{Code|quotes}} | | {{Code|quotes}} | ||
− | | Specifies | + | | 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 {{Code|backslashes}} option. | ||
| {{Code|yes}}, {{Code|no}} | | {{Code|yes}}, {{Code|no}} | ||
+ | | {{Code|yes}} | ||
| {{Code|yes}} | | {{Code|yes}} | ||
|- valign="top" | |- valign="top" | ||
| {{Code|backslashes}} | | {{Code|backslashes}} | ||
− | | Specifies | + | | Specifies how quotes and other characters are escaped: |
+ | * Parsing: If the option is enabled, {{Code|\r}}, {{Code|n}} and {{Code|\t}} will be replaced with the corresponding control characters. All other escaped characters will be adopted as literals (e.g.: {{Code|\"}} → {{Code|"}}). If the option is disabled, two consecutive quotes will be replaced with a single quote (unless {{Code|quotes}} is enabled and the quote is the first or last character of a value). | ||
+ | * Serialization: If the option is enabled, {{Code|\r}}, {{Code|n}}, {{Code|\t}}, {{Code|"}} and the separator character will be encoded with a backslash. If the option is disabled, quotes will be duplicated. | ||
| {{Code|yes}}, {{Code|no}} | | {{Code|yes}}, {{Code|no}} | ||
+ | | {{Code|no}} | ||
| {{Code|no}} | | {{Code|no}} | ||
|} | |} | ||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
=Functions= | =Functions= | ||
Line 95: | Line 95: | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|csv:parse|$input as xs:string|document-node(element(csv))}}<br/>{{Func|csv:parse|$input as xs:string, $options as item()|item()}} | + | |{{Func|csv:parse|$input as xs:string|document-node(element(csv))}}<br/>{{Func|csv:parse|$input as xs:string, $options as map(xs:string, item())|item()}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
Line 105: | Line 105: | ||
==csv:serialize== | ==csv:serialize== | ||
+ | |||
{| width='100%' | {| width='100%' | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|csv:serialize|$input as node()|xs:string}}<br/>{{Func|csv:serialize|$input as node(), $options as item()|xs:string}} | + | |{{Func|csv:serialize|$input as node()|xs:string}}<br/>{{Func|csv:serialize|$input as node(), $options as map(xs:string, item())|xs:string}} |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
Line 150: | Line 151: | ||
'''Query:''' | '''Query:''' | ||
<pre class="brush:xquery"> | <pre class="brush:xquery"> | ||
− | |||
let $options := map { 'lax': false() } | let $options := map { 'lax': false() } | ||
− | let $ | + | let $input := file:read-text('some-data.csv') |
− | let $csv := csv:serialize( | + | let $output := $input => csv:parse($options) => csv:serialize($options) |
− | return $ | + | return $input eq $output |
</pre> | </pre> | ||
Line 162: | Line 162: | ||
<pre class="brush:xquery"> | <pre class="brush:xquery"> | ||
let $text := "Name;City" || out:nl() || "John;Newton" || out:nl() || "Jack;Oldtown" | let $text := "Name;City" || out:nl() || "John;Newton" || out:nl() || "Jack;Oldtown" | ||
− | let $options := | + | let $options := map { |
− | + | 'separator': ';', | |
− | + | 'format' : 'map', | |
− | + | 'header' : true() | |
− | + | } | |
− | |||
return csv:parse($text, $options) | return csv:parse($text, $options) | ||
</pre> | </pre> | ||
'''Result:''' | '''Result:''' | ||
− | <pre class="brush: | + | <pre class="brush:xquery"> |
− | { | + | map { |
− | 1: { | + | 1: map { |
"City": "Newton", | "City": "Newton", | ||
"Name": "John" | "Name": "John" | ||
}, | }, | ||
− | 2: { | + | 2: map { |
"City": "Oldtown", | "City": "Oldtown", | ||
"Name": "Jack" | "Name": "Jack" | ||
Line 199: | Line 198: | ||
=Changelog= | =Changelog= | ||
+ | |||
+ | ;Version 8.6 | ||
+ | |||
+ | * Updated: [[#Options|Options]]: improved Excel compatibility | ||
;Version 8.0 | ;Version 8.0 | ||
Line 210: | Line 213: | ||
The module was introduced with Version 7.7.2. | The module was introduced with Version 7.7.2. | ||
− | |||
− |
Revision as of 16:18, 11 February 2017
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:
- The resulting XML document has a
<csv>
root element. - Rows are represented via
<record>
elements. - Fields are represented via
<entry>
elements. The value of a field is represented as text node. - If the
header
option is set totrue
, the first text line is parsed as table header, and the<entry>
elements are replaced with the field names:- Empty names are represented by a single underscore (
_
), and characters that are not valid in element names are replaced with underscores or (when invalid as first character of an element name) prefixed with an underscore. - If the
lax
option is set tofalse
, invalid characters will be rewritten to an underscore and the character’s four-digit Unicode, and underscores will be represented as two underscores (__
). The resulting element names may be less readable, but can always be converted back to the original field names.
- Empty names are represented by a single underscore (
- If
format
is set toattributes
, field names will be stored in name attributes.
Map
If format
is set to map
, the CSV data will be converted to an XQuery map:
- All records are enumerated with positive integers.
- By default, all entries of a records are represented in a sequence.
- If the
header
option is set totrue
, a map is created, which contains all field names and its values.
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
Template:Mark: 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:
|
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:
|
yes , no
|
yes
|
yes
|
backslashes
|
Specifies how quotes and other characters are escaped:
|
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
- Updated: Options: improved Excel compatibility
- Version 8.0
- Added:
backslashes
option
- Version 7.8
- Updated: csv:parse now returns a document node instead of an element, or an XQuery map if
format
is set tomap
. - Added:
format
andlax
options
The module was introduced with Version 7.7.2.