Question 172959 in Json Question posted in
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Can Jackson limit the size of string values for all keys in Json?

I have a dynamic nested json string and I wanted to limit the string value of all keys to have max length of 5 chars.

Using: Java fasterxml.jackson

For Json String like below:
`String inputJsonString = "{"key1":"bla bla bla bla","key2":{"key21":"bla bla bla"}}";`

I wanted this result:
`String outputJsonString = "{"key1":"bla b","key2":{"key21":"bla b"}}";`

For Json String like this:
`String inputJsonString = "{"fname":"bla bla bla bla","address":{"street":"bla bla bla"}}";`

I wanted this result:
`String outputJsonString = "{"fname":"bla b","address":{"street":"bla b"}}";`

Thanks!

Tags:

2

Answers


  1. 0

    Try this.

    public static void main(String[] args) throws JsonMappingException, JsonProcessingException {
    ObjectMapper mapper = new ObjectMapper();
    String inputJsonString = "{"key1":"bla bla bla bla","key2":{"key21":"bla bla bla"},"key3":[{"key21":"bla bla bla"}]}";
    System.out.println(inputJsonString);
    JsonNode jsonNode = mapper.readTree(inputJsonString);

    truncateStringValues(jsonNode);

    System.out.println(jsonNode);

}

private static void truncateStringValues(JsonNode jsonNode) throws JsonMappingException, JsonProcessingException {
    if (jsonNode.isArray()) {
        for (JsonNode arrayItem : jsonNode) {
            truncateStringValues(arrayItem);
        }

    } else if (jsonNode.isObject()) {
        Iterator<Entry<String, JsonNode>> fields = jsonNode.fields();
        while (fields.hasNext()) {
            Entry<String, JsonNode> jsonField = fields.next();
            JsonNode jsonFieldValue = jsonField.getValue();
            if (!jsonFieldValue.isContainerNode()) {
                ((ObjectNode) jsonNode).put(jsonField.getKey(), jsonFieldValue.asText().substring(0, 5));
            } else {
                truncateStringValues(jsonFieldValue);
            }
        }
    }
}
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  2. 0

    Great answer, John Williams!

    Just a quick note: Due to my current reputation level, I am unable to leave a comment, hence the need for this lengthy remark. Nevertheless, I wanted to mention a minor detail that could prevent a java.lang.StringIndexOutOfBoundsException when truncating strings shorter than 5 characters. To handle this, you can use Math.min with substring to extract up to 5 characters:

    String text = jsonFieldValue.asText();
objectNode.put(entry.getKey(), text.substring(0, Math.min(text.length(), 5)));

    This ensures a safe truncation. Thank you!

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