Added JMESPath filter to_boolean() (#6292)

* added to_boolean in JMESPath Filter

Signed-off-by: Abhishek Sawan <sawanabhi157@gmail.com>

* updated to_boolean JMESPath filter

Signed-off-by: Abhishek Sawan <sawanabhi157@gmail.com>

* updated to_boolean JMESPath filter with function registration

Signed-off-by: Abhishek Sawan <sawanabhi157@gmail.com>

* fixed to_boolean JMESPath filter with function registration

Signed-off-by: Abhishek Sawan <sawanabhi157@gmail.com>

* Update pkg/engine/jmespath/functions.go

Signed-off-by: Charles-Edouard Brétéché <charles.edouard@nirmata.com>

* fix

Signed-off-by: Charles-Edouard Brétéché <charles.edouard@nirmata.com>

---------

Signed-off-by: Abhishek Sawan <sawanabhi157@gmail.com>
Signed-off-by: Charles-Edouard Brétéché <charles.edouard@nirmata.com>
Co-authored-by: Charles-Edouard Brétéché <charled.breteche@gmail.com>
Co-authored-by: Charles-Edouard Brétéché <charles.edouard@nirmata.com>

pkg/engine/jmespath/functions.go

@@ -49,6 +49,7 @@ var (
 	regexMatch             = "regex_match"
 	patternMatch           = "pattern_match"
 	labelMatch             = "label_match"
+	toBoolean              = "to_boolean"
 	add                    = "add"
 	subtract               = "subtract"
 	multiply               = "multiply"
@@ -226,6 +227,16 @@ func GetFunctions() []FunctionEntry {
 		},
 		ReturnType: []jpType{jpBool},
 		Note:       "object arguments must be enclosed in backticks; ex. `{{request.object.spec.template.metadata.labels}}`",
+	}, {
+		FunctionEntry: gojmespath.FunctionEntry{
+			Name: toBoolean,
+			Arguments: []argSpec{
+				{Types: []jpType{jpString}},
+			},
+			Handler: jpToBoolean,
+		},
+		ReturnType: []jpType{jpBool},
+		Note:       "It returns true or false for any string, such as 'True', 'TruE', 'False', 'FAlse', 'faLSE', etc.",
 	}, {
 		FunctionEntry: gojmespath.FunctionEntry{
 			Name: add,
@@ -736,6 +747,21 @@ func jpLabelMatch(arguments []interface{}) (interface{}, error) {
 	return true, nil
 }
 
+func jpToBoolean(arguments []interface{}) (interface{}, error) {
+	if input, err := validateArg(toBoolean, arguments, 0, reflect.String); err != nil {
+		return nil, err
+	} else {
+		switch strings.ToLower(input.String()) {
+		case "true":
+			return true, nil
+		case "false":
+			return false, nil
+		default:
+			return nil, formatError(genericError, toBoolean, fmt.Sprintf("lowercase argument must be 'true' or 'false' (provided: '%s')", input.String()))
+		}
+	}
+}
+
 func jpAdd(arguments []interface{}) (interface{}, error) {
 	op1, op2, err := ParseArithemticOperands(arguments, add)
 	if err != nil {

pkg/engine/jmespath/functions_test.go

@@ -597,6 +597,35 @@ func Test_LabelMatch(t *testing.T) {
 	}
 }
 
+func Test_JpToBoolean(t *testing.T) {
+	testCases := []struct {
+		input    interface{}
+		expected interface{}
+		err      bool
+	}{
+		{"true", true, false},
+		{"TRue", true, false},
+		{"FaLse", false, false},
+		{"FaLsee", nil, true},
+		{"false", false, false},
+		{"foo", nil, true},
+		{1, nil, true},
+		{nil, nil, true},
+	}
+	for _, tc := range testCases {
+		res, err := jpToBoolean([]interface{}{tc.input})
+		if tc.err && err == nil {
+			t.Errorf("Expected an error but received nil")
+		}
+		if !tc.err && err != nil {
+			t.Errorf("Expected nil error but received: %s", err)
+		}
+		if res != tc.expected {
+			t.Errorf("Expected %v but received %v", tc.expected, res)
+		}
+	}
+}
+
 func Test_Base64Decode(t *testing.T) {
 	jp, err := New("base64_decode('SGVsbG8sIHdvcmxkIQ==')")
 	assert.NilError(t, err)

pkg/engine/jmespath/utils.go

@@ -8,6 +8,9 @@ func validateArg(f string, arguments []interface{}, index int, expectedType refl
 	if index >= len(arguments) {
 		return reflect.Value{}, formatError(argOutOfBoundsError, f, index+1, len(arguments))
 	}
+	if arguments[index] == nil {
+		return reflect.Value{}, formatError(invalidArgumentTypeError, f, index+1, expectedType.String())
+	}
 	arg := reflect.ValueOf(arguments[index])
 	if arg.Type().Kind() != expectedType {
 		return reflect.Value{}, formatError(invalidArgumentTypeError, f, index+1, expectedType.String())