将 MSCRM.SuppressDuplicateDetection 标头添加到 CRM Dynamics Web API 请求会提供 HTTP 412 代码

Question

We are using the WEB API of Microsoft CRM Dynamics online (v9.0)

Everything works fine with 'normal' create en read operations but when we want to use the duplication detection feature, the Microsoft webservice returns with 412.

URL obj = new URL(fullOdataURL);
HttpsURLConnection con = (HttpsURLConnection) obj.openConnection();
con.setRequestMethod("POST");

con.setRequestProperty("Content-Type", "application/json");
con.setRequestProperty("Authorization", "Bearer " + accesstoken);
con.setRequestProperty("OData-MaxVersion", "4.0");
con.setRequestProperty("OData-Version", "4.0");
con.setRequestProperty("MSCRM.SuppressDuplicateDetection", "false");

In the CRM web UI, the duplicate detection works, see screenshot

Answer 1

The HyperText Transfer Protocol (HTTP) 412 Precondition Failed client error response code indicates that access to the target resource has been denied. This happens with conditional requests on methods other than GET or HEAD when the condition defined by the If-Unmodified-Since or If-None-Match headers is not fulfilled. In that case, the request, usually an upload or a modification of a resource, cannot be made and this error response is sent back.

Reference

So, in your request add this below header:

If-None-Match: null

Documentation

con.setRequestProperty("If-None-Match", null);