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+# TwingleCampaign API
+
+The TwingleCampaign API is meant to offer a simple and secure interface to read and alter only a limited number of
+values provided by the TwingleProject API.
+
+It can be used by external CMS (like Drupal) to receive a list of TwingleProjects. The API delivers for example the
+embed codes of all active TwingleProjects so that they can be integrated in a website.
+
+It's also possible to update the TwingleProject `url` field via the TwingleCampaign Create API. In this case the `url`
+fields of all TwingleCampaign children of the TwingleProject will be updated, too.
+
+## Get & Getsingle API
+
+*Note: The Getsingle API delivers only one result or returns an error.*
+
+### API parameters
+
+|parameter               |required|description                                           |example value|
+|------------------------|:------:|------------------------------------------------------|-------------|
+|**id**                  |no      |campaign id                                           |16           |
+|**name**                |no      |name of the TwingleProject campaign                   |Donation_Form|
+|**title**               |no      |title of the TwingleProject campaign                  |Donation Form|
+|**twingle_project_type**|no      |project type can be *default*, *event* or *membership*|default      |
+
+### Example Get call
+```curl
+curl --location -g --request GET 'http://dmaster.localhost:7979/sites/all/modules/civicrm/extern/rest.php?entity=TwingleForm&action=get&api_key=xxxxxxxxxxxxxxxxxxxx&key=xxxxxxxxxxxxxxxxxxxx&json={}'
+```
+
+### Response for successful Get call
+```json
+{
+    "is_error": 0,
+    "version": 3,
+    "count": 2,
+    "values": {
+        "16": {
+            "id": "16",
+            "twingle_project_id": "3237",
+            "title": "Donation Form",
+            "name": "Donation_Form",
+            "project_type": "default",
+            "embed_code": "<!-- twingle --> ... <!-- twingle -->",
+            "counter": "https://donationstatus.twingle.de/donation-status/xxxxxxxxxxxx"
+        },
+        "23": {
+            "id": "23",
+            "twingle_project_id": "3242",
+            "title": "Another Donation Form",
+            "name": "Donation_Form_Copy",
+            "project_type": "event",
+            "embed_code": "<!-- twingle --> ... <!-- twingle -->",
+            "counter": "https://donationstatus.twingle.de/donation-status/xxxxxxxxxxxx"
+        }
+    }
+}
+```
+
+### Example Getsingle call
+```curl
+curl --location -g --request GET 'http://dmaster.localhost:7979/sites/all/modules/civicrm/extern/rest.php?entity=TwingleForm&action=getsingle&api_key=xxxxxxxxxxxxxxxxxxxx&key=xxxxxxxxxxxxxxxxxxxx&json={%22id%22:16}' \
+```
+
+### Response for successful Getsingle call
+```json
+{
+    "is_error": 0,
+    "version": 3,
+    "count": 7,
+    "values": {
+        "id": "16",
+        "twingle_project_id": "3237",
+        "title": "Donation Form",
+        "name": "Donation_Form",
+        "project_type": "default",
+        "embed_code": "<!-- twingle --> ... <!-- twingle -->",
+        "counter": "https://donationstatus.twingle.de/donation-status/xxxxxxxxxxxx"
+    }
+}
+```
+
+## Create API
+
+### Create API parameters
+
+|parameter|required|description                                   |example value                     |
+|---------|:------:|----------------------------------------------|----------------------------------|
+|**id**   |yes     |campaign id                                   |16                                |
+|**url**  |yes     |url of the page where Twingle form is embedded|https://mywebsite.org/donationform|
+
+### Example Create call
+
+```curl
+curl --location -g --request POST 'http://dmaster.localhost:7979/sites/all/modules/civicrm/extern/rest.php?entity=TwingleForm&action=create&api_key=xxxxxxxxxxxxxxxxxxxx&key=xxxxxxxxxxxxxxxxxxxx&json={%22id%22:%2016,%20%22url%22:%22https://mywebsite.org/donationform%22}'
+```
+
+### Response for successful Create call
+
+```json
+{
+  "is_error": 0,
+  "version": 3,
+  "count": 5,
+  "values": {
+    "title": "Donation Form",
+    "id": "16",
+    "project_id": "3237",
+    "project_type": "default",
+    "status": "TwingleProject created"
+  }
+}
+```
+
+### Responses for failed Create calls
+
+#### TwingleProject not found
+
+```json
+{
+  "id": 999,
+  "url": "https://mywebsite.org/donationform",
+  "is_error": 1,
+  "error_message": "Expected one TwingleProject but found 0"
+}
+```
+
+#### Invalid URL
+
+```json
+{
+  "id": 16,
+  "url": "https://mywebsite.org/donation form",
+  "is_error": 1,
+  "error_message": "invalid URL"
+}
+```
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