A guide on using JSONPath to parse a JSON object and filter based on a specific string value within an array nested inside the

Question

A guide on using JSONPath to parse a JSON object and filter based on a specific string value within an array nested inside the

Below is a sample JSON that I have listed down. I am looking to create a JSONPath that selects elements where the subject includes "Maths".

Please note that I am utilizing Goessner's JSONPath with the Newtonsoft library in C#.

{
   "class":{
      "type":"group",
      "identifier":"MyFavClass",
      "subs":[
         {
            "type":"individual",
            "identifier":"Rambo"
         },
         {
            "type":"individual",
            "identifier":"Rancho"
         },
         {
            "type":"biggroup",
            "identifier":"village",
            "subjects":[
               "Maths",
               "English"
            ]
         },
         {
            "type":"biggroup",
            "identifier":"newvillage",
            "subjects":[
               "Maths"
            ]
         }
      ]
   }
}

c#json json.net jsonpath

Answer 1

Answer №1

If you are utilizing the SelectTokens() method in Json.NET for your JSONPath searches, you can locate all math subjects with this query:

var value = "Maths";

var subjects = root.SelectTokens($"class.subs[*].subjects[?(@ == '{value}')]");

This will return a sequence of JValue tokens containing the value "Maths". If you want the class.subs[*] objects that have "Maths" in their subjects[*] arrays, do this:

var subs = root.SelectTokens($"class.subs[?(@.subjects[?(@ == '{value}')])]");

Some important notes to consider:

The [?(...)] filter expression applies a condition ... to an array.
In filter expressions, primitive values within arrays can be identified using the @ symbol representing the current object.
Json.NET's JSONPath implementation allows nested queries inside array filter expressions. Hence,
```
[?(@.subjects[?(@ == '{value}')])]
```
selects array elements with items in their "subjects" array matching the specified value.
Please note that if your search value includes a single quote ', it must be escaped as demonstrated in Querying JSON with JSON Path and escaped properties. For example, to match Math's, escape it like this:
```
var value = "Math's".Replace("'", "\\\'");
```

Check out the demonstration fiddle here.

Answer 2

If you are utilizing the SelectTokens() method in Json.NET for your JSONPath searches, you can locate all math subjects with this query:

var value = "Maths";

var subjects = root.SelectTokens($"class.subs[*].subjects[?(@ == '{value}')]");

This will return a sequence of JValue tokens containing the value "Maths". If you want the class.subs[*] objects that have "Maths" in their subjects[*] arrays, do this:

var subs = root.SelectTokens($"class.subs[?(@.subjects[?(@ == '{value}')])]");

Some important notes to consider:

The [?(...)] filter expression applies a condition ... to an array.
In filter expressions, primitive values within arrays can be identified using the @ symbol representing the current object.
Json.NET's JSONPath implementation allows nested queries inside array filter expressions. Hence,
```
[?(@.subjects[?(@ == '{value}')])]
```
selects array elements with items in their "subjects" array matching the specified value.
Please note that if your search value includes a single quote ', it must be escaped as demonstrated in Querying JSON with JSON Path and escaped properties. For example, to match Math's, escape it like this:
```
var value = "Math's".Replace("'", "\\\'");
```

Check out the demonstration fiddle here.

A guide on using JSONPath to parse a JSON object and filter based on a specific string value within an array nested inside the

Answer №1

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