~davidagraf/zorba/trace_without_debug

<html><head><title>JSON for XQuery</title><style type="text/css">@import url('https://themes.googleusercontent.com/fonts/css?kit=lhDjYqiy3mZ0x6ROQEUoUw');ol{margin:0;padding:0}p{margin:0}.c22{max-width:468pt;background-color:#ffffff;padding:72pt 72pt 72pt 72pt}.c19{list-style-type:disc;margin:0;padding:0}.c6{padding-left:0pt;text-align:justify;margin-left:36pt}.c0{height:11pt;direction:ltr}.c3{color:#38761d;font-family:Consolas}.c2{color:inherit;text-decoration:inherit}.c4{color:#1155cc;text-decoration:underline}.c1{direction:ltr}.c20{height:18pt}.c9{margin-left:58.5pt}.c13{text-indent:139.5pt}.c17{text-indent:144pt}.c7{margin-left:144pt}.c8{text-align:right}.c11{font-weight:bold}.c16{text-align:justify}.c10{margin-left:36pt}.c5{font-family:Consolas}.c18{color:#38761d}.c15{margin-left:49.5pt}.c21{text-align:center}.c23{color:#4a86e8}.c12{font-style:italic}.c14{margin-left:18pt}.title{padding-top:24pt;line-height:1.15;text-align:center;color:#4a86e8;font-size:36pt;font-family:Arial;font-weight:bold;padding-bottom:6pt}.subtitle{padding-top:18pt;line-height:1.15;text-align:left;color:#666666;font-style:italic;font-size:24pt;font-family:Georgia;padding-bottom:4pt}body{color:#000000;font-size:11pt;font-family:Arial}h1{padding-top:24pt;line-height:1.15;text-align:left;color:#4a86e8;font-size:24pt;font-family:Arial;font-weight:bold;padding-bottom:6pt}h2{padding-top:18pt;line-height:1.15;text-align:left;color:#ff9900;font-size:18pt;font-family:Arial;font-weight:bold;padding-bottom:4pt}h3{padding-top:14pt;line-height:1.15;text-align:left;color:#000000;font-size:14pt;font-family:Arial;font-weight:bold;padding-bottom:4pt}h4{padding-top:12pt;line-height:1.15;text-align:left;color:#000000;font-size:12pt;font-family:Arial;font-weight:bold;padding-bottom:2pt}h5{padding-top:11pt;line-height:1.15;text-align:left;color:#000000;font-size:11pt;font-family:Arial;font-weight:bold;padding-bottom:2pt}h6{padding-top:10pt;line-height:1.15;text-align:left;color:#000000;font-size:10pt;font-family:Arial;font-weight:bold;padding-bottom:2pt}</style></head><body class="c22"><a name="h.li2wdq8unbq"></a>JSONiq for XQuery users<a name="h.5ipqqclfxk4n"></a>JSON for XQuery<hr>This tutorial introduces the JSONiq language, which declaratively manipulates JSON data.Why don't you go ahead can try the queries of this document on our online demo interface? <a class="c2" href="http://jsoniq.zorba-xquery.com/">http://jsoniq.zorba-xquery.com/</a><hr><h2 class="c1 c20"><a name="h.8gra0ylxutrv"></a></h2><a class="c2" href="#h.f453h84m2u1a">JSON</a><a class="c2" href="#h.qtfakecy3fr7">Elevator Pitch</a><a class="c2" href="#h.yugk1mszt0re">And here you go</a><a class="c2" href="#h.39rm37noeh9g">JSONiq types</a><a class="c2" href="#h.j0wg8654ivtw">JSON Constructors</a><a class="c2" href="#h.qe57mgdf5ql">JSON as a subset of JSONiq</a><a class="c2" href="#h.mjv7kyjurri2">JSON Navigation</a><a class="c2" href="#h.xosiyb17dh24">Objects</a><a class="c2" href="#h.mrf42gizl3y6">Arrays</a><a class="c2" href="#h.hdc3dgohtdut">Pairs</a><a class="c2" href="#h.eb0bxle2oykl">Relational Algebra</a><a class="c2" href="#h.oii6pvliilhi">Access external data</a><a class="c2" href="#h.bm3buqmzhtko">I want more</a><h1 class="c1"><a name="h.f453h84m2u1a"></a>JSON</h1>As explained on <a class="c2" href="http://www.json.org/">http://www.json.org/</a>, JSON is a lightweight data-interchange format designed for humans as well as for computers. It supports as values:<ol class="c19" start="1"><li class="c6 c1">objects (string-to-value map)</li><li class="c6 c1">arrays (ordered sequence of values)</li><li class="c6 c1">strings</li><li class="c6 c1">numbers</li><li class="c6 c1">booleans (true, false)</li><li class="c6 c1">null</li></ol>JSONiq extends XQuery to query and update JSON data, like XML data.<h1 class="c1"><a name="h.qtfakecy3fr7"></a>Elevator Pitch</h1>Here is an appetizer before we start the tutorial from scratch.let $stores :=[  { "store number" : 1, "state" : "MA" },  { "store number" : 2, "state" : "MA" },  { "store number" : 3, "state" : "CA" },  { "store number" : 4, "state" : "CA" }]let $sales := [   { "product" : "broiler", "store number" : 1, "quantity" : 20  },   { "product" : "toaster", "store number" : 2, "quantity" : 100 },   { "product" : "toaster", "store number" : 2, "quantity" : 50 },   { "product" : "toaster", "store number" : 3, "quantity" : 50 },   { "product" : "blender", "store number" : 3, "quantity" : 100 },   { "product" : "blender", "store number" : 3, "quantity" : 150 },   { "product" : "socks", "store number" : 1, "quantity" : 500 },   { "product" : "socks", "store number" : 2, "quantity" : 10 },   { "product" : "shirt", "store number" : 3, "quantity" : 10 }]let $join :=  for $store in jn:values($stores), $sale in jn:values($sales)  where $store("store number") = $sale("store number")  return {    "nb" : $store("store number"),    "state" : $store("state"),    "sold" : $sale("product")  }return [$join][   { "nb" : 1, "state" : "MA", "sold" : "broiler" },  { "nb" : 1, "state" : "MA", "sold" : "socks" },  { "nb" : 2, "state" : "MA", "sold" : "toaster" },  { "nb" : 2, "state" : "MA", "sold" : "toaster" },  { "nb" : 2, "state" : "MA", "sold" : "socks" },  { "nb" : 3, "state" : "CA", "sold" : "toaster" },  { "nb" : 3, "state" : "CA", "sold" : "blender" },  { "nb" : 3, "state" : "CA", "sold" : "blender" },  { "nb" : 3, "state" : "CA", "sold" : "shirt" } ]<h1 class="c1"><a name="h.yugk1mszt0re"></a>And here you go</h1><h2 class="c1"><a name="h.39rm37noeh9g"></a>JSONiq types</h2>JSONiq maps JSON types to XQuery. Numbers are xs:integer or xs:decimal, strings are xs:string, true and false are xs:boolean and null is a new atomic type jn:null.JSONiq introduces new items: objects, arrays and pairs. Objects have pairs. Pairs have a string name and a value. Array have members which are values. Values are objects, arrays, XML nodes or atomic items.The new item types for objects and arrays are object() and array(). json-item() is a supertype of both, and json-pair() is the item type for pairs.<h2 class="c1"><a name="h.j0wg8654ivtw"></a>JSON Constructors</h2>JSONiq introduces JSON constructors, in a similar way to XML constructors.You can put any expression in a array. The items in the sequence produced by the expression will become members of the array:[ 1 to 10 ][ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]Or you can dynamically compute an object:{  "Greeting" : (let $d := "Mister Spock"                return concat("Hello, ", $d)),  "Farewell" : string-join(("Live", "long", "and", "prosper"),                           " ")}{ "Greeting" : "Hello, Mister Spock", "Farewell" : "Live long and prosper" }You can also dynamically generate pairs:concat("Integer ", 2) : 2 * 2"Integer 2" : 4and then wrap lots of them in an object:{  for $i in 1 to 10  return concat("Square of ", $i) : $i * $i}{"Square of 1" : 1,"Square of 2" : 4,"Square of 3" : 9,"Square of 4" : 16,"Square of 5" : 25,"Square of 6" : 36,"Square of 7" : 49,"Square of 8" : 64,"Square of 9" : 81,"Square of 10" : 100}<h2 class="c1"><a name="h.qe57mgdf5ql"></a>JSON as a subset of JSONiq</h2>Every well-formed JSON document is a JSONiq query as well. This means that you can copy-and-paste a JSON document into a query. The following are JSONiq queries that are "idempotent" (they just output themselves):{ "pi" : 3.14, "sq2" : 1.4 }{ "pi" : 3.14, "sq2" : 1.4 }[ 2, 3, 5, 7, 11, 13 ][ 2, 3, 5, 7, 11, 13 ]{  "operations" : [    { "binary" : [ "and", "or"] },    { "unary" : ["not"] }  ],  "bits" : [    0, 1  ]}{  "operations" : [    { "binary" : [ "and", "or" ] },    { "unary" : [ "not" ] }  ],  "bits" : [    0, 1  ]}This works with objects, arrays (even nested), strings, numbers, booleans, null. The exceptions to this rule (but we are working on it!) are that:(i) if a pair has a true, false or null value, there must be a space on at least one side of the colon (this will be fixed).(ii) empty objects are not recognized(iii) characters escaped with the \ in JSON strings are not recognizedIt also works the other way round: if your query outputs an object or an array, you can readily use it as a JSON document.<h1 class="c1"><a name="h.mjv7kyjurri2"></a>JSON Navigation</h1>If you have some JSON data, you can access it and navigate.All you need to know is, again: JSONiq views<ol class="c19" start="1"><li class="c1 c6">an array as a sequence of values,</li><li class="c6 c1">an object as a set of pairs,</li><li class="c6 c1">a pair as a (name, value) tuple.</li></ol><h2 class="c1 c16"><a name="h.xosiyb17dh24"></a>Objects</h2>If you use an object as a functor and provide it with a string, it will return the pair named after its parameter:let $person := {  "first name" : "Sarah",  "age" : 13,  "gender" : "female",  "friends" : [ "Jim", "Mary", "Jennifer"]}return $person("first name")"first name" : "Sarah"<h2 class="c1"><a name="h.mrf42gizl3y6"></a>Arrays</h2>If you use an array as a functor and provide it with an integer, it will return the corresponding entry:let $friends := [ "Jim", "Mary", "Jennifer"]return $friends(2)Mary<h2 class="c1"><a name="h.hdc3dgohtdut"></a>Pairs</h2>Given a pair, you can get its name and value using the functions jn:name and jn:value:let $pair := "name of the pair" : "value of the pair"return {  "name" : jn:name($pair), "value" : jn:value($pair) }{ "name" : "name of the pair", "value" : "value of the pair" }This functions also exist in plural form for objects:let $person := {  "name" : "Sarah",  "age" : 13,  "gender" : "female",  "friends" : [ "Jim", "Mary", "Jennifer"]}return { "names" : [ jn:names($person)],         "values" : [ jn:values($person)]       }{"names" : [ "name", "age", "gender", "friends" ],"values" : [ "Sarah", 13, "female", [ "Jim", "Mary", "Jennifer" ] ]}jn:values can also be used for an array:let $person := {  "name" : "Sarah",  "age" : 13,  "gender" : "female",  "friends" : [ "Jim", "Mary", "Jennifer"]}return jn:values($person("friends"))[ "Jim", "Mary", "Jennifer" ]<h1 class="c1"><a name="h.eb0bxle2oykl"></a>Relational Algebra</h1>Remember last century's SELECT FROM WHERE statements? Well, JSONiq didn't throw out the baby with the bathwater. It has selection, projection and join capability.let $stores :=[  { "store number" : 1, "state" : "MA" },  { "store number" : 2, "state" : "MA" },  { "store number" : 3, "state" : "CA" },  { "store number" : 4, "state" : "CA" }]let $sales := [   { "product" : "broiler", "store number" : 1, "quantity" : 20  },   { "product" : "toaster", "store number" : 2, "quantity" : 100 },   { "product" : "toaster", "store number" : 2, "quantity" : 50 },   { "product" : "toaster", "store number" : 3, "quantity" : 50 },   { "product" : "blender", "store number" : 3, "quantity" : 100 },   { "product" : "blender", "store number" : 3, "quantity" : 150 },   { "product" : "socks", "store number" : 1, "quantity" : 500 },   { "product" : "socks", "store number" : 2, "quantity" : 10 },   { "product" : "shirt", "store number" : 3, "quantity" : 10 }]let $join :=  for $store in jn:values($stores), $sale in jn:values($sales)  where $store("store number") = $sale("store number")  return {    "nb" : $store("store number"),    "state" : $store("state"),    "sold" : $sale("product")  }return [$join][ { "nb" : 1, "state" : "MA", "sold" : "broiler" },{ "nb" : 1, "state" : "MA", "sold" : "socks" },{ "nb" : 2, "state" : "MA", "sold" : "toaster" },{ "nb" : 2, "state" : "MA", "sold" : "toaster" },{ "nb" : 2, "state" : "MA", "sold" : "socks" },{ "nb" : 3, "state" : "CA", "sold" : "toaster" },{ "nb" : 3, "state" : "CA", "sold" : "blender" },{ "nb" : 3, "state" : "CA", "sold" : "blender" },{ "nb" : 3, "state" : "CA", "sold" : "shirt" } ]<h1 class="c1"><a name="h.oii6pvliilhi"></a>Access external data</h1>Our implementation supports collections of JSON objects or arrays:dml:collection("my:data"){ "foo" : "Your" }{ "foo" : "Collection" }{ "foo" : "of" }{ "foo" : "JSON" }{ "foo" : "objects" }It is also possible to get JSON content with an HTTP request, or by parsing it from a string. Functions that handle this are available.<h1 class="c1"><a name="h.fopcxnkoydgt"></a>JSON and XML</h1>You can readily use XML and JSON in the same program. If you put a JSON array in an XML constructor, it will be flattened (its member values are recursively taken, even in arrays of arrays). If you put a JSON pair in an XML constructor, it will be unboxed (its value is taken).let $data := {   "color" : "blue",   "closed" : true,   "points" : [[10,10], [20,10], [20,20], [10,20]]   }let $stroke := attribute stroke { $data("color") }let $points := attribute points { $data("points") }return  if ($data("closed")) then    <svg><polygon>{ $stroke, $points }</polygon></svg>  else    <svg><polyline>{ $stroke, $points }</polyline></svg><?xml version="1.0" encoding="UTF-8"?><svg><polygon stroke="blue" points="10 10 20 10 20 20 10 20"/></svg><h1 class="c1"><a name="h.bm3buqmzhtko"></a>I want more</h1>JSONiq supports JSON updates. You can declaratively update your JSON data. JSONiq provides functions that produce a list of updates. The list of updates that is eventually output by your program is then applied to your JSON data.let $my-data := jn:json("persons.json")let $john := jn:value($my-data("John"))let $mary := jn:value($my-data("Mary"))return (jn:replace-value($john, "status", "married"),        j:replace-value($mary, "status", "married"))JSONiq works with the XQuery 3.0 standard (switch, typeswitch and try-catch expressions, universal/existential quantifiers, path expressions, filtering expressions, functors, mappings, grouping, windowing will work). The Zorba implementation is also compatible with the proprietary Zorba scripting.</body></html>

b'\\ No newline at end of file'

Older »