Dynamics CRM 2015/2016新特性之二十六：使用Web API执行乐观并发操作

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执行乐观并发的更新或者删除，关键的修改是增加 If-Match 这个请求头。每次查询记录都会返回记录的版本号。示例代码如下：

var clientURL = Xrm.Page.context.getClientUrl();
var req = new XMLHttpRequest()
req.open("GET", encodeURI(clientURL + "/api/data/v8.0/ly_tests(94B750DA-17B9-E511-80DC-000D3A804C3F)?$select=ly_name"), true);
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) {
        req.onreadystatechange = null;
        if (this.status == 200) {
            var responseJSON = JSON.parse(this.responseText);
            Xrm.Utility.alertDialog("查询到的记录的版本号是" + responseJSON["@odata.etag"] + " ，请修改记录后点击确定!");
            req.open("PATCH", encodeURI(clientURL + "/api/data/v8.0/ly_tests(94B750DA-17B9-E511-80DC-000D3A804C3F)"), true);
            req.setRequestHeader("If-Match", responseJSON["@odata.etag"]);
            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 /* complete */) {
                    req.onreadystatechange = null;
                    if (this.status == 204) {
                        Xrm.Utility.alertDialog("记录修改成功!")
                    }
                    else {
                        var error = JSON.parse(this.response).error;
                        Xrm.Utility.alertDialog("修改罗勇测试实体记录出错." + error.message);
                    }
                }
            };
            var test = {};
            test.ly_name = "单行文本";//单行文本
            req.send(JSON.stringify(test));
        }
        else {
            var error = JSON.parse(this.responseText).error;
            Xrm.Utility.alertDialog("查询罗勇测试实体记录出错." + error.message);
        }
    }
};
req.send();

测试截图如下，证实有效。

 

更多信息请参考官方文档：Perform conditional operations using the Web API 。