[英]JSON-LD blank node to nested object in Apache Jena
I have the following example Turtle document:我有以下示例 Turtle 文档:
@prefix dct: <http://purl.org/dc/terms/> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix example: <http://example.com/vocabulary/> .
@prefix dcat: <http://www.w3.org/ns/dcat#> .
<http://example.com/datasets/1>
a dcat:Distribution ;
example:props [ example:prop1 "hello" ;
example:prop2 "1"
] ;
dct:description "test data" .
I converted it into JSON-LD with the Apache Jena (RDFDataMgr with JSONLD_COMPACT_PRETTY) to JSON-LD:我使用 Apache Jena(带有 JSONLD_COMPACT_PRETTY 的 RDFDataMgr)将它转换为 JSON-LD 到 JSON-LD:
{
"@context": {
"dct": "http://purl.org/dc/terms/",
"rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
"dcat": "http://www.w3.org/ns/dcat#",
"example": "http://example.com/vocabulary/"
},
"@graph": [
{
"@id": "_:b0",
"example:prop1": "hello",
"example:prop2": "1"
},
{
"@id": "http://example.com/datasets/1",
"@type": "dcat:Distribution",
"example:props": {
"@id": "_:b0"
},
"dct:description": "test data"
}
]
}
But actually I want to have a nested object instead of a blank node:但实际上我想要一个嵌套对象而不是一个空白节点:
{
"@context": {
"dct": "http://purl.org/dc/terms/",
"rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
"dcat": "http://www.w3.org/ns/dcat#",
"example": "http://example.com/vocabulary/"
},
"@graph": [
{
"@id": "http://example.com/datasets/1",
"@type": "dcat:Distribution",
"example:props": {
"example:prop1": "hello",
"example:prop2": "1"
},
"dct:description": "test data"
}
]
}
Is that possible with Apache Jena? Apache Jena 可以实现吗? And is it semantically equivalent?它在语义上是等价的吗?
Apache Jena uses jsonld-java for JSON-LD input and output. Apache Jena 使用 jsonld-java 进行 JSON-LD 输入和输出。
It is possible to setup the jsonld-java output as shown with:可以设置jsonld-java输出,如下所示:
https://jena.apache.org/documentation/io/rdf-output.html#json-ld ==> https://github.com/apache/jena/blob/master/jena-arq/src-examples/arq/examples/riot/Ex_WriteJsonLD.java https://jena.apache.org/documentation/io/rdf-output.html#json-ld ==> https://github.com/apache/jena/blob/master/jena-arq/src-examples/ arq/examples/riot/Ex_WriteJsonLD.java
You'll need to consult jsonld-java as to whether the writer can do what you want.您需要咨询jsonld-java以了解作者是否可以做您想做的事。
You can use jsonld-java with framing to convert your JSON-LD result to nice nested JSON .您可以使用带框架的jsonld-java将您的JSON-LD 结果转换为漂亮的嵌套 JSON 。 The result of the conversion will be semantically equivalent.转换的结果在语义上是等效的。
Try尝试
private static String getPrettyJsonLdString(String rdfGraphAsJson) {
try {
//@formatter:off
return JsonUtils
.toPrettyString(
getFramedJson(
createJsonObject(
rdfGraphAsJson)));
//@formatter:on
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private static Map<String, Object> getFramedJson(Object json) {
try {
return JsonLdProcessor.frame(json, getFrame(), new JsonLdOptions());
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private static Map<String, Object> getFrame() {
Map<String, Object> frame = new HashMap<>();
/*
Use @type to define 'root' object to embed into
*/
frame.put("@type" , "dcat:Distribution");
Map<String,Object>context=new HashMap<>();
context.put("dct", "http://purl.org/dc/terms/");
context.put("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#");
context.put("dcat", "http://www.w3.org/ns/dcat#");
context.put("example", "http://example.com/vocabulary/");
frame.put("@context", context);
return frame;
}
private static Object createJsonObject(String ld) {
try (InputStream inputStream =
new ByteArrayInputStream(ld.getBytes(Charsets.UTF_8))) {
Object jsonObject = JsonUtils.fromInputStream(inputStream);
return jsonObject;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
This will produce这将产生
{
"@context" : {
"dct" : "http://purl.org/dc/terms/",
"rdf" : "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
"dcat" : "http://www.w3.org/ns/dcat#",
"example" : "http://example.com/vocabulary/"
},
"@graph" : [ {
"@id" : "http://example.com/datasets/1",
"@type" : "dcat:Distribution",
"example:props" : {
"@id" : "_:b0",
"example:prop1" : "hello",
"example:prop2" : "1"
}
} ]
}
You need to re-frame the graph as the top-level object.您需要将图形重新构建为顶级对象。 You can use either:您可以使用:
{
"@context": ...,
"@type": "dcat:Distribution"
}
or或者
{
"@context": ...,
"@id": "http://example.com/datasets/1"
}
or或者
{
"@context": ...,
"example:props": {}
}
(ie object that contains any "example:props"). (即包含任何“example:props”的对象)。
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