CRM2016中新增的web api支持fetch xml了，之前使用FetchXML的场景是在后天代码中通过组织服务的retrieve multiple方法，但实际的应用效果有多大，还需要在实际的项目中去体会了。

上代码，注意要对fetch xml进行编码

 var fetch="<fetch mapping='logical'>"

           +"<entity name='account'>"

           +"<attribute name='accountid'/> "

           + "<attribute name='name'/> "

            + "<attribute name='primarycontactid'/> "

           +"</entity>"

           + "</fetch>"

  var req = new XMLHttpRequest()

  req.open("get", Xrm.Page.context.getClientUrl() + "/api/data/v8.0/accounts?fetchXml="+ encodeURI(fetch), false);

  req.setRequestHeader("Accept", "application/json");

  req.setRequestHeader("Content-Type", "application/json; charset=utf-8");

  req.setRequestHeader("OData-MaxVersion", "4.0");

  req.setRequestHeader("OData-Version", "4.0");

  req.onreadystatechange = function () {

      if (this.readyState == 4) {

          if (this.status == 200) {

              var data = JSON.parse(this.responseText);

          }

          else {

              var data = JSON.parse(this.responseText).error.message;

          }

      }

  };

  req.send();

下图是查询出的结果