Can we use CAML query in Rest Api. If yes then how?

Ans:- Yes we can use CAML query with Rest Api. In some terms, when you needed to do some complicated query in a SP list. To do these queries you can prefer CAML.

It always has to be a POST request. The request header is the same as the other normal post requests for SharePoint Rest API.

headers: {

         "X-RequestDigest": $("#__REQUESTDIGEST").val(),

         'content-type': 'application/json;odata=verbose',

         'accept': 'application/json;odata=verbose'

}

The REST endpoint for using CAML query is:

/_api/web/lists/GetByTitle('<List Name>')/GetItems

The complete code with the REST call is given below:

// Include JQuery reference

// ... script continues ...

        /// List Name and CAML Query as Parameter

        function restCallwithCaml(listName, caml) {

             /// get the site url

             var siteUrl = _spPageContextInfo.siteAbsoluteUrl;

             /// set request data     

             var data = { "query" : {"__metadata": { "type": "SP.CamlQuery" }, 

                                                      "ViewXml":caml}

                               };

             /// make an ajax call

             $.ajax({

                url: siteUrl+"/_api/web/lists/GetByTitle

                ('"+ listName +"')/GetItems",

                method: "POST",

                data: data,

                headers: {

                   "X-RequestDigest": $("#__REQUESTDIGEST").val(),

                   'content-type': 'application/json;odata=verbose',

                   'accept': 'application/json;odata=verbose'

                }

                success: function (response) {

                    ///do your code

                },

                error: function (data) {

                  ///do your code

                }

            });

       }

The CAML Query has to use in between this <View><Query>…CAML Query…</Query></View> tag. The query with the way to call the function is given below:

var caml = "<View><Query><Where><Eq><FieldRef Name='EndDate' /><Value Type='DateTime'><Today /></Value></Eq></Where></View></Query>";

restCallwithCaml(<listName>, caml);