SnackJson

A Json framework with support for JsonDom, JsonPath, JsonSchema (for Java)

Compatible ` jayway. Jsonpath ` and IETF jsonpath (RFC 9535) standard. Compatible with JsonSchema Draft07 standard. Support for open customization.

https://solon.noear.org/article/snack

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Language: English | 中文

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SnackJson draws on the design of Javascript where all variables are declared with var and Xml dom where everything is Node. Everything underneath it is represented by an ONode, which stands for One node and can be converted to any type.

• Emphasize the ability to build and manipulate the Json dom
• High performance Json path queries (much faster than jayway.jsonpath), Compatible with jayway.jsonpath and IETF JSONPath (RFC 9535) standards (Switch with optoins). Deliver the next generation of JsonPath experiences.
• Provides Json schema construction and validation, compatible with JsonSchema draw-07, draw-2019 standards
• Support some 'json5' features (keyless fields, comments, etc...)
• Prefer no-argument constructors + field codec (reduces the risk of triggering actions by injection)

dependencies	description
org.noear:snack4	Provides json dom building and codec support
org.noear:snack4-jsonpath	Provides json path query support
org.noear:snack4-jsonschema	Provides json schema validation support

JSONPath syntax reference ( IETF JSONPath (RFC 9535) )

Syntax Element	Description
$	root node identifier
@	current node identifier (valid only within filter selectors)
[<selectors>]	child segment: selects zero or more children of a node
.name	shorthand for ['name']
.*	shorthand for [*]
..[<selectors>]	descendant segment: selects zero or more descendants of a node
..name	shorthand for ..['name']
..*	shorthand for ..[*]
'name'	name selector: selects a named child of an object
*	wildcard selector: selects all children of a node
3	index selector: selects an indexed child of an array (from 0)
0:100:5	array slice selector: start:end:step for arrays
?<logical-expr>	filter selector: selects particular children using a logical expression
fun(@.foo)	filter function: invokes a function in a filter expression (IETF standard)
.fun()	aggregate function: Used as a fragment (jayway style)

Filter selector syntax reference:

Syntax	Description	Precedence
(...)	Grouping	5
name(...)	Function Expressions	5
!	Logical NOT	4
==,!=,<,<=,>,>=	Relations	3
&&	Logical AND	2
||	Logical OR	1

IETF JSONPath (RFC 9535) Standard definition operators (supported)

Operator	Description	Examples
==	left is equal to right (note that 1 is not equal to '1')	$[?(@.a == 1)]
!=	left is not equal to right	$[?(@.a != 1)]
<	left is less than right	$[?(@.a < 1)]
<=	left is less or equal to right	$[?(@.a <= 1)]
>	left is greater than right	$[?(@.a > 1)]
>=	left is greater than or equal to right	$[?(@.a >= 1)]

jayway.jsonpath Increment operator (supported)

Operator	Description	Examples
=~	left matches regular expression	[?(@.s =~ /foo.*?/i)]
in	left exists in right	[?(@.s in ['S', 'M'])]
nin	left does not exists in right
subsetof	left is a subset of right	[?(@.s subsetof ['S', 'M', 'L'])]
anyof	left has an intersection with right	[?(@.s anyof ['M', 'L'])]
noneof	left has no intersection with right	[?(@.s noneof ['M', 'L'])]
size	size of left (array or string) should match right	$[?(@.s size @.expected_size)]
empty	left (array or string) should be empty	$[?(@.s empty false)]

IETF JSONPath (RFC 9535) Standard definition functions (supported)

Function	Description	Parameter types	Result types
length(x)	The length of a string, array, or object	Value	Numerical value
count(x)	Size of the node list	Node list	Numerical value
match(x,y)	The regular expression matches exactly	Value,Value	Logical value
search(x,y)	Regular expression substring matching	Value,Value	Logical value
value(x)	The value of a single node in a node list	Node list	Value

jayway.jsonpath Functions (supported)

Function	Description	Output type
min()	Provides the min value of an array of numbers	Double
max()	Provides the max value of an array of numbers	Double
avg()	Provides the average value of an array of numbers	Double
stddev()	Provides the standard deviation value of an array of numbers	Double
length()	Provides the length of an array	Integer
sum()	Provides the sum value of an array of numbers	Double
keys()	Provides the property keys (An alternative for terminal tilde ~)	Set<E>
concat(X)	Provides a concatinated version of the path output with a new item	like input
append(X)	add an item to the json path output array	like input
first()	Provides the first item of an array	Depends on the array
last()	Provides the last item of an array	Depends on the array
index(X)	Provides the item of an array of index: X, if the X is negative, take from backwards	Depends on the array

snack-jsonpath Increment operator (supported)

Operator	Description	Examples
startsWith	left (string) start matches a right	[?(@.s startsWith 'a')]
endsWith	left (string) end matches the right	[?(@.s endsWith 'b')]
contains	left (array or string) contains matches the right	[?(@.s contains 'c')]

JSONPath syntax examples

Example JSON Value

{ "store": {
"book": [
{ "category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{ "category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
},
{ "category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{ "category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
],
"bicycle": {
"color": "red",
"price": 399
}
}
}

Example JSONPath Expressions and Their Intended Results When Applied to the Example JSON Value

JSONPath	Intended Result
$.store.book[*].author	the authors of all books in the store
$..autho	all authors
$.store.*	all things in the store, which are some books and a red bicycle
$.store..price	the prices of everything in the store
$..book[2]	the third book
$..book[2].author	the third book's author
$..book[2].publisher	empty result: the third book does not have a "publisher" member
$..book[-1]	the last book in order
$..book[0,1] $..book[:2]	the first two books
$..book[?@.isbn]	all books with an ISBN number
$..book[?@.price<10]	all books cheaper than 10
$..*	all member values and array elements contained in the input value

Let's look at some application examples

Support dom manipulation

ONodeoNode = newONode();
oNode.set("id", 1);
oNode.getOrNew("layout").then(o -> {
o.addNew().set("title", "开始").set("type", "start");
o.addNew().set("title", "结束").set("type", "end");
});
oNode.get("id").getInt();
oNode.get("layout").get(0).get("title").getString();
oNode.getOrNew("list").fillJson("[1,2,3,4,5,6]");

Supports json path query, build, and delete

ONode.ofBean(store).select("$..book[?@.tags contains 'war'].first()").toBean(Book.class); //RFC9535 规范，可以没有括号ONode.ofBean(store).select("$..book[?(!(@.category == 'fiction') && @.price < 40)].first()").toBean(Book.class);
ONode.ofJson(store).select("$.store.book.count()");
ONode.ofBean(store).create("$.store.book[0].category").toJson();
ONode.ofBean(store).delete("$..book[-1]");

Supports json schema validation

JsonSchemaschema = JsonSchema.ofJson("{type:'object',properties:{userId:{type:'string'}}}"); //加载架构定义schema.validate(ONode.ofJson("{userId:'1'}")); //校验格式

Supports serialization and deserialization

Useruser = newUser();
ONode.ofBean(user).toBean(User.class); //可以作为 bean 转换使用ONode.ofBean(user).toJson();
ONode.ofJson("{}").toBean(User.class);
ONode.ofJson("[{},{}]").toBean((newArrayList<User>(){}).getClass()); //泛型ONode.ofJson("[{},{}]").toBean(newTypeRef<List<User>>(){}); //泛型//快捷方式Stringjson = ONode.serialize(user);
Useruser = ONode.deserialize(json, User.class);

Path tree interface

//case1ONodeo = ONode.ofJson(json); ONoderst = o.select("$.data.list[*].mobile"); //自动为查询到的节点，生成 path 属性List<String> rstPaths = rst.pathList(); //获取结果节点的路径列表for(ONoden1 : rst.getArray()) {
n1.path(); //当前路径n1.parent(); //父级节点
}
//case2ONodeo = ONode.ofJson(json).usePaths(); //手动为每个子节点，生成 path 属性ONoderst = o.get("data").get("list").get(2);
rst.path();
rst.parent();

Advanced customization

Json codec customization

Optionsoptions = Options.of();
//添加编码器options.addEncoder(Date.class, (ctx, value, target) -> {
target.setValue(DateUtil.format(data, "yyyy-MM-dd"));
});
//添加解码器options.addDecoder(Date.class, ...);
//添加创建器（接管类实例化）options.addCreator(...);
//添加特性options.addFeature(Feature.Write_PrettyFormat);
//移除特性options.removeFeature(Feature.Write_PrettyFormat);
//设置日期格式附options.addFeature(Feature.Write_UseDateFormat); //使用日期格式options.dateFormat("yyyy-MM");
//..Stringjson = ONode.ofBean(orderModel, options).toJson();

JsonPath Function and operator customization

importorg.noear.snack4.ONode;
importorg.noear.snack4.jsonpath.FunctionLib;
publicclassFunctionDemo {
publicstaticvoidmain(String[] args) {
//定制 floor 函数FunctionLib.register("floor", (ctx, argNodes) -> {
ONodearg0 = argNodes.get(0); //节点列表（选择器的结果）if (ctx.isDescendant()) {
for (ONoden1 : arg0.getArray()) {
if (n1.isNumber()) {
n1.setValue(Math.floor(n1.getDouble()));
}
}
returnarg0;
} else {
ONoden1 = arg0.get(0);
if (n1.isNumber()) {
returnctx.newNode(Math.floor(n1.getDouble()));
} else {
returnctx.newNode();
}
}
});
//检验效果（在 IETF 规范里以子项进行过滤，即 1,2） //out: 1.0System.out.println(ONode.ofJson("{'a':1,'b':2}")
.select("$.a.floor()")
.toJson());
//参考 //out: 2.0System.out.println(ONode.ofJson("{'a':1,'b':2}")
.select("$[?floor(@) > 1].first()")
.toJson());
}
}

importorg.noear.snack4.ONode;
importorg.noear.snack4.jsonpath.OperatorLib;
publicclassOperationDemo {
publicstaticvoidmain(String[] args) {
//定制操作符OperatorLib.register("startsWith", (ctx, node, term) -> {
ONodeleftNode = term.getLeftNode(ctx, node);
if (leftNode.isString()) {
ONoderightNode = term.getRightNode(ctx, node);
if (rightNode.isNull()) {
returnfalse;
}
returnleftNode.getString().startsWith(rightNode.getString());
}
returnfalse;
});
//检验效果assertONode.ofJson("{'list':['a','b','c']}")
.select("$.list[?@ startsWith 'a']")
.size() == 1;
}
}

Special thanks to JetBrains for supporting open-source projects：