Mastering JsonPath with Regex: Filter JSON Arrays and Validate Nodes

JSON Data Example

The article starts with a sample JSON object representing a store with a list of books and a bicycle, slightly modified from the official demo.

JSONObject json = JSON.parseObject("{
    \"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\": 19.95
        }
    },
    \"expensive\": 10,
    \"ss\": [32,32,4,23]
}");

Filtering Arrays with Regex

Using JsonPath, you can filter the book array by matching the author field with a regular expression. The expression $..book[?(@.author =~ /.*Rees/)] (or the equivalent $.store.book[?(@.author =~ /.*Rees/)]) selects books whose author name contains "Rees".

Object read = JsonPath.read(json, "$.store.book[?(@.author =~ /.*Rees/)]");
output(JSONArray.parseArray(read.toString()));

Console output shows the matching JSON object:

INFO-> 当前用户：fv，IP：10.60.192.21，工作目录：/Users/fv/Documents/workspace/fun/,系统编码格式:UTF-8,系统Mac OS X版本:10.15.6
~☢~~☢~~☢~~☢~~☢~~☢~~☢~~☢~~☢~~☢~ JSON ~☢~~☢~~☢~~☢~~☢~~☢~~☢~~☢~~☢~~☢~
>  {"author":"Nigel Rees","price":8.95,"category":"reference","title":"Sayings of the Century"}
Process finished with exit code 0

Case‑Insensitive Matching

JsonPath supports the /i flag to ignore case. The expression $.store.book[?(@.author =~ /.*REES/i)] matches the same author regardless of letter case.

Object read = JsonPath.read(json, "$.store.book[?(@.author =~ /.*REES/i)]");
output(JSONArray.parseArray(read.toString()).isEmpty()); // returns false

Object read2 = JsonPath.read(json, "$.store.book[?(@.author =~ /.*Rees/i)]");
output(JSONArray.parseArray(read2.toString()));

Console output confirms the case‑insensitive match returns the expected JSON object.

Regex Validation of Node Values

The article notes that direct regex validation of a node's value is not currently supported by JsonPath. The author mentions plans to wrap functionality to add this capability.