[BUGFIX] Using array instead of object for json_encode.

json_encode(object) was returning empty braces "{}"

Classes/SGalinski/TypoScriptReferenceFrontend/Domain/Model/Attribute.php

@@ -320,4 +320,47 @@ class Attribute {
 
 		return $this;
 	}
+
+	/**
+	 * Writes object properties to associative array. NULL and not-set properties are ignored.
+	 *
+	 * @return array
+	 */
+	public function toArray() {
+		$attributeArray = [];
+		if (isset($this->id)) {
+			$attributeArray ['id'] = $this->id;
+		}
+		if (isset($this->name)) {
+			$attributeArray ['name'] = $this->name;
+		}
+		if (isset($this->description)) {
+			$attributeArray ['description'] = $this->description;
+		}
+		if (isset($this->default)) {
+			$attributeArray ['default'] = $this->default;
+		}
+		if (isset($this->minVersion)) {
+			$attributeArray ['minVersion'] = $this->minVersion;
+		}
+		if (isset($this->maxVersion)) {
+			$attributeArray ['maxVersion'] = $this->maxVersion;
+		}
+		if (isset($this->parent)) {
+			$attributeArray ['parent'] = $this->parent->getId();
+		}
+		if (isset($this->type)) {
+			$attributeArray ['type'] = $this->type->getId();
+		}
+		if (isset($this->typo3Group)) {
+			$attributeArray ['typo3Group'] = $this->typo3Group;
+		}
+		if (isset($this->deleted)) {
+			$attributeArray ['deleted'] = $this->deleted;
+		}
+		if (isset($this->isType)) {
+			$attributeArray ['isType'] = $this->isType;
+		}
+		return $attributeArray;
+	}
 }

Classes/SGalinski/TypoScriptReferenceFrontend/Service/TsrefRestService.php

@@ -172,11 +172,7 @@ class TsrefRestService {
 	 * @return mixed
 	 */
 	public function addNewAttribute(Attribute $attribute) {
-		$attributeJson = json_encode($attribute);
-		echo 'AttributeName: ' . $attribute->getName();
-		echo 'Attribute JSON: ' . $attributeJson;
-		// json that works example: '{"name":"testNamePUT","description":"Testing PUT modify. cetvrtak","minVersion":"4.2","maxVersion":"7.2","typo3Group":2,"isType":false,"deleted":false, "parent":"181"}'
-
+		$attributeJson = json_encode($attribute->toArray());
 		$curlHandle = $this->initialiseCurl();
 
 		curl_setopt($curlHandle, CURLOPT_POST, 1);
@@ -185,7 +181,7 @@ class TsrefRestService {
 			'accesstoken: ' . self::AUTHENTICATION_TOKEN
 		]);
 		curl_setopt($curlHandle, CURLOPT_POSTFIELDS, $attributeJson);
-		curl_setopt($curlHandle, CURLOPT_RETURNTRANSFER, true);
+		curl_setopt($curlHandle, CURLOPT_RETURNTRANSFER, TRUE);
 
 		// Download the given URL, and return output
 		$output = curl_exec($curlHandle);