Sample code for 30+ languages & platforms
C#

Find a Label ID by Name

See more GMail REST API Examples

Lookup the ID of a GMail label by the label name.

Chilkat C# Downloads

C#
bool success = false;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

Chilkat.Http http = new Chilkat.Http();
http.AuthToken = "GMAIL-ACCESS-TOKEN";

string userId = "me";
http.SetUrlVar("userId",userId);

string url = "https://www.googleapis.com/gmail/v1/users/{$userId}/labels";

//  Get the list of GMail labels as JSON.
Chilkat.StringBuilder sb = new Chilkat.StringBuilder();
success = http.QuickGetSb(url,sb);
if (success != true) {
    Debug.WriteLine(http.LastErrorText);
    return;
}

Chilkat.JsonObject json = new Chilkat.JsonObject();
json.LoadSb(sb);
json.EmitCompact = false;
Debug.WriteLine(json.Emit());

if (http.LastStatus != 200) {
    Debug.WriteLine("Failed.");
    return;
}

//  The JSON returned looks like this:
//  {
//    "labels": [
//      {
//        "id": "Label_5",
//        "name": "QA",
//        "messageListVisibility": "show",
//        "labelListVisibility": "labelShow",
//        "type": "user"
//      },
//      {
//        "id": "Label_21",
//        "name": "[Gmail]/testFolder",
//        "type": "user"
//      },
//      {
//        "id": "CATEGORY_PERSONAL",
//        "name": "CATEGORY_PERSONAL",
//        "type": "system"
//      },
//  	...

//  The name of the label is generally known because it's what we visually see.
//  The id is what we need to get.  Assuming the name is unique,
//  find the JSON record having name=<desired name>
//  For example...
Chilkat.JsonObject jRecord = json.FindRecord("labels","name","QA",false);
if (json.LastMethodSuccess == true) {
    Debug.WriteLine("The id of QA is: " + jRecord.StringOf("id"));

}

jRecord = json.FindRecord("labels","name","[Gmail]/testFolder",false);
if (json.LastMethodSuccess == true) {
    Debug.WriteLine("The id of [Gmail]/testFolder is: " + jRecord.StringOf("id"));

}

jRecord = json.FindRecord("labels","name","questions",false);
if (json.LastMethodSuccess == true) {
    Debug.WriteLine("The id of questions is: " + jRecord.StringOf("id"));

}

//  Output:

//  The id of QA is: Label_5
//  The id of [Gmail]/testFolder is: Label_21
//  The id of questions is: Label_43