在Power Apps中使用环境变量

笛里谁知壮士心,沙头空照征人骨。这篇文章主要讲述在Power Apps中使用环境变量相关的知识,希望能为你提供帮助。
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环境变量(environment variable) 大概在 2019年11月开始Preview,可以参考官方博文:??Environment variables available in preview!??? 。最近已经GA了,可以放心使用了,官方文档请参考:??Environment variables available in preview!  ??  。有点很多,官方文档列举的优点如下,我就不翻译了。

  • No need to manually edit configurable values in a production environment.
  • Configure one or more variables in one place and reference like a parameter across multiple solution components.
  • Enter different values while importing solutions to other environments.
  • Update values without a code change.
  • Granular level security managed by  ??Microsoft Dataverse??.
  • Unlimited number of variables (max solution size is 29 MB).
  • Service the definitions and the values independently or together.
  • Supported by  ??SolutionPackager???  and  ??DevOps??  tools enable continuous integration and continuous delivery (CI/CD).
  • Support for localization.
  • Can be used to control feature flags and other application settings.
如果要创建环境变量,到 make.powerapps.com 中打开的solution中点击New > Environment variable来新建。



可以看到环境变量的新建界面如下,对于稍微复杂一点的数据类型,我很一般喜欢使用 JSON 这种数据类型。





然后程序如何获取环境变量的值呢?我这里列举的代码示例如下:
public static string GetEnvironmentVariableValue(string variableSchemaName, IOrganizationService service, ITracingService tracingService)

if (string.IsNullOrEmpty(variableSchemaName))

throw new InvalidPluginExecutionException("环境变量名称为空,中止查询该变量的值!");

string returnVal = string.Empty;
var fetchXml = string.Format(@"< fetch version=1.0 mapping=logical top=1 no-lock=true>
< entity name=environmentvariabledefinition>
< attribute name=defaultvalue/>
< filter type=and>
< condition attribute=schemaname operator=eq value=https://www.songbingjia.com/android/0/>
< condition attribute=statecode operator=eq value=https://www.songbingjia.com/android/0/>
< /filter>
< link-entity name=environmentvariablevalue from=environmentvariabledefinitionid to=environmentvariabledefinitionid link-type=outer alias=varvalue>
< attribute name=value/>
< /link-entity>
< /entity>
< /fetch> ", variableSchemaName);
var ec = service.RetrieveMultiple(new FetchExpression(fetchXml));
if (ec.Entities.Count > = 1)

if (ec.Entities[0].Contains("varvalue.value"))

returnVal = ec.Entities[0].GetAttributeValue< AliasedValue> ("varvalue.value").Value.ToString();

else

returnVal = ec.Entities[0].GetAttributeValue< string> ("defaultvalue");


tracingService.Trace($"名称为variableSchemaName环境变量的值是returnVal");
return returnVal;



通过javascript同步获取环境变量值版本:

function getClientUrl()
if (typeof GetGlobalContext == "function" & & typeof GetGlobalContext().getClientUrl == "function")
return GetGlobalContext().getClientUrl();
else
return Xrm.Utility.getGlobalContext().getClientUrl();


function getWebAPIPath()
return getClientUrl() + "/api/data/v9.2/";

this.getEnvironmentVariableValueSync = function (variableSchemaName)
/// < summary> 同步获取环境变量的值< /summary>
/// < param name="variableSchemaName" type="String"> 环境变量的名称< /param>
var returnVal = ""; var req = new XMLHttpRequest();
req.open("GET", encodeURI(getWebAPIPath() + "environmentvariabledefinitions?$select=defaultvalue& $expand=environmentvariabledefinition_environmentvariablevalue($select=value)& $filter=schemaname eq " + variableSchemaName + "& $top=1"), 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)
req.onreadystatechange = null; if (this.status == 200)
var respJson = JSON.parse(req.responseText); if (respJson.value.length === 1)
if (respJson.value[0]["environmentvariabledefinition_environmentvariablevalue"] & & respJson.value[0]["environmentvariabledefinition_environmentvariablevalue"].length > = 1)
returnVal = respJson.value[0]["environmentvariabledefinition_environmentvariablevalue"][0].value;
else
returnVal = respJson.value[0].defaultvalue;




;
req.send(); return returnVal;



利用  Xrm.WebApi.retrieveMultipleRecords 的代码示例是:
Xrm.WebApi.retrieveMultipleRecords("environmentvariabledefinition", "?$select=defaultvalue,displayname& $expand=environmentvariabledefinition_environmentvariablevalue($select=value)& $filter=schemaname eq ly_demoev& $top=1").then(function success(result)
if (result.entities.length === 1)
if (result.entities[0]["environmentvariabledefinition_environmentvariablevalue"]
& & result.entities[0]["environmentvariabledefinition_environmentvariablevalue"].length > 0)
console.log("值是" + result.entities[0]["environmentvariabledefinition_environmentvariablevalue"][0].value);
else if (result.entities[0].defaultvalue)
console.log("值是" + result.entities[0].defaultvalue);
else
console.log("环境变量的值是空");


, function (error)
console.log(error.message);

);

【在Power Apps中使用环境变量】

在Cloud Flow中可以直接引用环境变量的值,不需要查询,这个比较方便。


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