MarkLogic 10 Product Documentationxdmp:from-json-string
xdmp:from-json-string( $arg as xs:string ) as item()*
Summary
Parses a string as JSON, returning an item sequence.
| Parameters | |
|---|---|
| arg | JSON input to be parsed. |
Usage Notes
A JSON object or string is parsed as a json:object.
The JSON null value is represented as the empty sequence, and serializes
in a way that indicates it is a null value. Therefore, when the null value
is returned to JSON via xdmp:to-json, the null value is
preserved.
Nested arrays in JSON are turned into nested sets of
json:arrays.
Any codepoints in the JSON string that aren't allowed in XML are rejected and an error is thrown.
Example
xdmp:from-json-string('["a", null, false]')
=>
json:array(
<json:array xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:json="http://marklogic.com/xdmp/json">
<json:value xsi:type="xs:string">a</json:value>
<json:value xsi:nil="true"/>
<json:value xsi:type="xs:boolean">false</json:value>
</json:array>)
Example
xquery version "1.0-ml";
let $json :=
'[{"some-key":45683}, "this is a string", 123]'
return
xdmp:from-json-string($json)
=>
json:array(
<json:array xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:json="http://marklogic.com/xdmp/json">
<json:value>
<json:object>
<json:entry key="some-key">
<json:value xsi:type="xs:integer">45683</json:value>
</json:entry>
</json:object>
</json:value>
<json:value xsi:type="xs:string">this is a string</json:value>
<json:value xsi:type="xs:integer">123</json:value></json:array>)
Note that what is shown above is the serialization of the XQuery items to
a json:array. You can also use some or all of the items in the XQuery data
model. For example, consider the following, which adds to the map based on the
other values:
xquery version "1.0-ml";
let $json :=
'[{"some-key":45683}, "this is a string", 123]'
let $items := xdmp:from-json-string($json)
let $put := map:put($items[1], xs:string($items[3]), $items[2])
return
($items[1], xdmp:to-json-string($items[1]))
(: returns the following json:array and JSON string:
json:object(
<json:object xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:json="http://marklogic.com/xdmp/json">
<entry key="some-key">
<json:value xsi:type="xs:integer">45683</json:value>
</entry>
<entry key="123">
<json:value xsi:type="xs:string">this is a string</json:value>
</entry>
</json:object>)
{"some-key":45683, "123":"this is a string"}
This query uses the map functions to modify the first json:object
in the json:array.
:)