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420 bytes added ,  14:40, 16 April 2019
=Conventions=
All functions and errors in this module are assigned to the <code><nowiki>http://basex.org/modules/csv</nowiki></code> namespace, which is statically bound to the {{Code|csv}} prefix.<br/>All errors are assigned to the <code><nowiki>http://basex.org/errors</nowiki></code> namespace, which is statically bound to the {{Code|bxerr}} prefix.
==Conversion==
===XML: Direct, Attributes===
If the {{Code|direct}} or {{Code|attributes}} format is chosen, a CSV string is converted to XML as follows:
* The resulting XML document has a {{Code|<csv>}} root element.
===XQuery===
With the {{MarkCode|Introduced with Version 9.0xquery}}: format, CSV records can be are converted to a sequence of arrays:
* The resulting value will be a map with a {{Code|records}} and an optional {{Code|names}} key.
* The column names will be available if {{Code|header}} option is set to {{Code|true}}.
The CSV map can e.g. be accessed as follows: * <code>$csv?records[5]</code> returns all entries of the 5th record (row)* <code>$csv?records(2)</code> returns all entries of the 2nd field (column)* <code>$csv?names?*</code> returns the names of all fields (if available)* Return enumerated strings for all records:<pre class="brush:xquery">for $record at $pos in $csv?recordsreturn $pos || ". " || string-join($record?*, ', ')</pre> The resulting representation will consume consumes less memory than XML-based formats, and values can be directly accessed without conversion. Thus, it is recommendable for very large inputs and for efficient ad-hoc processing.
==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.
* With {{Code|attributes}} conversion, field names are stored in {{Code|name}} attributes
* With {{Code|xquery}} conversion, the input is converted to an XQuery map
| {{Code|direct}}, {{Code|attributes}}, {{Code|mapxquery}}
| {{Code|direct}}
|
|-
| width='120' | '''Signatures'''
|{{Func|csv:parse|$input string as xs:string?|document-node(elementitem(csv))?}}<br/>{{Func|csv:parse|$input string as xs:string?, $options as map(xs:string, item()*)?|item()?}}
|-
| '''Summary'''
|Converts the CSV data specified by {{Code|$inputstring}} to an XML document or a mapXQuery value. The {{Code|$options}} argument can be used to control the way the input is converted.
|-
| '''Errors'''
|{{Error|BXCS0001parse|#Errors}} the input cannot be parsed.
|}
|-
| width='120' | '''Signatures'''
|{{Func|csv:serialize|$input as nodeitem()?|xs:string}}<br/>{{Func|csv:serialize|$input as nodeitem()?, $options as map(xs:string, item()*)?|xs:string}}
|-
| '''Summary'''
|Serializes the node specified by {{Code|$input}} as CSV data, and returns using the result as specified {{Code|xs:string$options}}, and returns the result as string. Items Values can also be serialized as JSON if CSV with the standard [[Serialization|Serialization Parameter]] feature of XQuery:* The parameter {{Code|method}} is needs to be set to {{Code|csv}}.<br/>The , and* the options presented in this article need to be assigned to the {{Code|$optionscsv}} argument can be used to control the way the input is serializedparameter.
|-
| '''Errors'''
|{{Error|BXCS0002serialize|#Errors}} the input cannot be serialized.
|}
]``
let $options := map { 'format': 'xquery', 'header': true() }
let $data csv := csv:parse($text, $options)
return (
'Distinct values:',
let $records := $data?csv('records') for $name at $pos in $data?csv('names')?*
let $values := $records?($pos)
return (
|Description
|-
|{{Code|BXCS0001parse}}
| The input cannot be parsed.
|-
|{{Code|BXCS0002serialize}}
| The node cannot be serialized.
|}
=Changelog=
 
; Version 9.1
* Updated: [[#csv:parse|csv:parse]] can be called with empty sequence.
;Version 9.0
* Added: {{Code|xquery}} option
* Removed: {{Code|map}} option
* Updated: error codes updated; errors now use the module namespace
;Version 8.6
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