Chapter V Modification implementation (impl) class

The fifth chapter Modify implementation （IMPL） class

This chapter discusses how to modify REST The implementation class of the service .

Initial method definition

Implementation classes initially contain stub methods , As shown in the following example ：

/// Returns all pets from the system that the user has access to<br/>
/// The method arguments hold values for:<br/>
/// tags, tags to filter by<br/>
/// limit, maximum number of results to return<br/>
ClassMethod findPets(tags As %ListOfDataTypes(ELEMENTTYPE="%String"), limit As %Integer) As %Stream.Object
{
    
    //(Place business logic here)
    //Do ..%SetStatusCode(<HTTP_status_code>)
    //Do ..%SetHeader(<name>,<value>)
    //Quit (Place response here) ; response may be a string, stream or dynamic object
}

In each case , These stub methods all follow REST The signature of the contract defined by the service specification .

Implementation method

For each method in the implementation class , According to the REST Call edit method definition （ Especially the realization ）. Please note that , This method is preceded by a comment , The note is corresponding REST A copy of the call description . In practice ：

• Return the appropriate value .
• Check the request message . So , Please use the implementation class %CheckAccepts()、%GetContentType() and %GetHeader() Method . All the methods mentioned here are from %REST.Impl inherited , It is a superclass of your implementation class .
• Set as needed HTTP Status code to indicate , for example , Whether resources are available . So , Please use %SetStatusCode() Method . of HTTP Status code information , see also http://www.faqs.org/rfcs/rfc2068.html.
• Set up HTTP Response headers . So , Please use %SetHeader()、%SetHeaderIfEmpty() and %DeleteHeader() Method .
• if necessary , Report error . So , Please use %LogError() Method .

Expose the details of the server error

By default , If REST The service encountered an internal error , The details of the error will not be reported to the client . To change this , Please add the following to the implementation class , Then recompile it ：

Parameter ExposeServerExceptions = 1;

Please note that , default %ReportRESTError() Method will check this parameter . If you override this method （ See the next title ）, You can choose whether the method uses this parameter .

Modify the error response

If you need to format the error response in a non default way , Please override %ReportRESTError() Method . In the method , Use %WriteResponse() Method returns an error response .