Json Rules

JSON serializable rules to match Jackson JsonNodes using JSON Pointers.

Rule

   {
      "type": "equals",
      "value": "happy",
      "path": "$.mood"
   }

Paylod

   {
      "name": "John Doe",
      "mood": "happy"
   }

Payload would match the rules when evaluated

Getting Started

Installation

Maven repo

  <dependency>
    <groupId>io.appform.rules</groupId>
    <artifactId>json-rules</artifactId>
    <version>1.0.12</version>
  </dependency>

Usage

    // Build expression with java objects
    Expression expression = LessThanExpression.builder()
                                .path("/$.value")
                                .value(30)
                                .build();
    // Or read from serialized json sources
    Expression expression = (new ObjectMapper()).readValue(expressionJson, Expression.class)
    
    // Get json payload to be evaluated
    JsonNode jsonNode = objectMapper.readTree(productJson);
    
    boolean matches = expression.evaluate(jsonNode);

Operators

General

• equals
• not_equals
• less_than
• greater_than
• less_than_equals
• greater_than_equals
• between (half-closed with lower bound included)

   {
      "type": "equals",
      "value": "happy",
      "path": "$.mood"
   }

Composite/Boolean operators

• and
• not
• or

   {
      "type": "and",
      "children": [
          {
             "type": "equals",
             "value": "happy",
             "path": "$.mood"
          },
          {
             "type": "less_than",
             "value": 1000,
             "path": "$.product.cost"
          }
      ]
   }

Collection Search

• not_in
• in
• contains_any
• contains_all

   {
      "type": "in",
      "path": "$.mood",
      "values": [
        "happy",
        "sad"
      ]
   }

Strings

• empty
• not_empty
• starts_with
• ends_with
• matches

The string operations of starts_with, ends_with and matches support case insensitive comparison also. Default comparison is case sensitive.

    {
        "type": "matches",
        "path": "$.s1",
        "value": ".* WORLD",
        "ignoreCase" : true
    }

Path validations

• exists
• not_exists

Default results

For unstructured json evaluation you can specify a defaultResult value. The default value would be the evaluation result if path doesn't exist in the evaluation payload.

   {
      "type": "equals",
      "value": "happy",
      "path": "$.mood",
      "defaultResult": true
   }

Preoperations

Pre-operations are pre-evaluation mutations that can be applied to payload.

• Datetime
  • Epoch - Mutation rules for unix timestamp
  • DateTime - Mutation rules for textual dates
• Numeric
  • Divide
  • Multiply
  • Sum
  • Difference
  • modulo
• Array
  • size
• String
  • length
  • sub_str

    {
        "type": "in",
        "path": "$.time",
        "preoperation": {
          "operation": "epoch",
          "operand": "week_of_month",
          "zoneOffSet": "+05:30"
        },
        "values": [
          2,
          4
        ]
    }

Path based comparisons

These allow comparison of dynamic values. Using "extractValueFromPath" : true, indicates the value to be used for comparison has to be extracted from value json path.

    {
        "type": "matches",
        "path": "$.s1",
        "value": "$.s2",
        "extractValueFromPath" : true
    }

Debuggability

Debuggability support is provided to understand exact reasons of rule failures for any given context. This support is extended across all the available operators.