Changes

This [[Module Library|XQuery Module]] contains a single function to parse CSV input. [httphttps://en.wikipedia.org/wiki/Comma-separated_values CSV] (comma-separated values) is a popular representation for tabular data, exported e. g. from Excel.

All functions and errors in this module are assigned to the {{Code|<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|http://basex.org/errors}} namespace, which is statically bound to the {{Code|bxerr}} prefix.

=Rules=Conversion==

{{Version|7.7.2}}===XML: the conversion rules have been updated and aligned with the JSON parser.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 elementselement.# * Rows are represented via {{Code|<record/>}} elements.# * Fields are represented via {{Code|<entry/>}} elements. The value of a field is represented as text node.# * If the {{Code|header}} option is set to {{Code|true}}, the first text line is parsed as table header, and the {{Code|entry}} elements are replaced with the field names:## Empty names are represented by a single underscore ({{Code|_}}), and characters that are not valid in element names are replaced with underscores.## ** If the {{Code|laxformat}} option is set to {{Code|falsedirect}}, invalid characters will be rewritten to an underscore and the character’s four-digit Unicodefield names are encoded, as described in the [[Conversion Module#Keys|Conversion Module]], and underscores will be represented used as two underscores ({{Code|__}}). The resulting element names may be less readable, but can always be converted back to the original field names.# If ** Otherwise, if {{Code|format}} is set to {{Code|attributes}}, the field names will be stored in name attributes.

If the JSON parser is selected '''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. ===XQuery=== With the {{Code|xquery}} format, CSV records are converted to a sequence of arrays: * The resulting value will be a map with a {{Code|records}} and an optional {{Code|names}} key.* Records are organized as a sequence of arrays. A single array contains the entries of a simple example single record.* The column names will be available if {{Code|header}} option is displayed set to show {{Code|true}}. The CSV map can e.g. be accessed as follows: * <code>$csv?records[5]</code> returns all entries of the effects 5th record (row)* <code>$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:<syntaxhighlight lang="xquery">for $record at $pos in $csv?recordsreturn $pos || ". " || string-join($record?*, ', ')</syntaxhighlight> The resulting representation 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== In the following table, all available optionsare 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%"|- valign="top"! width="140" | Option! width="50%" | Description! Allowed! Default! Excel|- valign="top"| {{Code|separator}}| 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}}|- valign="top"| {{Code|header}}| Indicates if the first line of the parsed or serialized CSV data is a table header.| {{Code|yes}}, {{Code|no}}| {{Code|no}}||- valign="top"| {{Code|format}}| Specifies the format of the XML data:<br/>* With {{Code|direct}} conversion, field names are represented as element names* 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|xquery}}| {{Code|direct}}||- valign="top"| {{Code|lax}}| Specifies if a lax approach is used to convert QNames to JSON names.| {{Code|yes}}, {{Code|no}}| {{Code|yes}}| {{Code|no}}|- valign="top"| {{Code|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 if it contains characters that might be treated as control characters. 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|yes}}|- valign="top"| {{Code|backslashes}}| 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|no}}| {{Code|no}}|}

|{{Func|csv:parse|$input string as xs:string?|elementitem(csv)?}}<br/>{{Func|csv:parse|$input string as xs:string?, $options as itemmap(*)?|elementitem(csv)?}}

|Converts the CSV data specified by {{Code|$inputstring}} to XML, and returns the result as {{Code|element(csv)}} an XQuery value.<br/>The {{Code|$options}} argument can be used to control the way the input is converted. The following options are available:* {{Code|separator}} defines the character which separates columns in a row. By default, this is a comma ({{Code|,}}).* {{Code|header}} specifies if the input contains a header row. The default value is {{Code|false}}.Options can either be specified<br />* as children of an {{Code|<csv:options/>}} element; e.g.:<pre class="brush:xml"><csv:options> <csv:separator value=';'/> ...</csv:options></pre>* or as map, which contains all key/value pairs:<pre class="brush:xquery">{ 'separator' : ';', ... }</pre>

|{{Error|BXCS0001parse|#Errors}} the specified input cannot be parsed as CSV document.|} ==csv:doc== {| width='100%'|-| width='120' | '''Signatures'''|{{Func|csv:doc|$uri as xs:string?|item()?}}<br />{{Func|csv:doc|$uri as xs:string?, $options as map(*)?|item()?}}<br />|-| '''Summary'''|Fetches the CSV document referred to by the given {{Code|$uri}} and converts it to an XQuery value. The {{Code|$options}} argument can be used to control the way the input is converted.|-| '''Errors'''|{{Error|parse|#Errors}} the specified input cannot be parsed as CSV document.<br/>{{Error|BXCS0003options|#Errors}} the specified separator must be a single characteroptions are conflicting.

|{{Func|csv:serialize|$input as nodeitem()?|xs:string}}<br/>{{Func|csv:serialize|$input as item()?, $options as itemmap(*)?|xs:string}}

|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.<br />XML documents Values can also be serialized as CSV if with the standard [[Serialization|Serialization Option]] feature of XQuery:* The parameter {{Code|method}} is needs to be set to {{Code|csv}}.<br/>The {{Code|$options}} argument can be used to control the way the node is serialized. The following options are available:, and* {{Code|separator}} defines the character which separates columns options presented in a row. By default, this is a comma ({{Code|,}}).* {{Code|header}} specifies if the input element names are article need to be interpreted as header names. The default value is assigned to the {{Code|false}}.Options can either be specified<br />* as children of an {{Code|<csv:options/>}} element; e.g.:<pre class="brush:xml"><csv:options> <csv:separator value=';'/> ..parameter.</csv:options></pre>* or as map, which contains all key/value pairs:<pre class="brush:xquery">{ 'separator' : ';', ... }</pre>

|{{Error|BXCS0002serialize|#Errors}} the input cannot be serialized.<br/>{{Error|BXCS0003|#Errors}} the specified separator must be a single character.

|{{Code|BXCS0001parse}}| The input cannot be convertedparsed.

|{{Code|BXCS0002serialize}}