create a mongodb JavaScript script to report on how many users own specified gear

database_reports/count_users_who_own_specified_gear.js

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+var itemsOfInterest = [
+    'headAccessory_special_wondercon_red',
+    'headAccessory_special_wondercon_black',
+    'back_special_wondercon_black',
+    'back_special_wondercon_red',
+    'body_special_wondercon_red',
+    'body_special_wondercon_black',
+    'body_special_wondercon_gold'
+];
+
+var itemsFound = {};  // each key is one item from itemsOfInterest, and
+        // the value for that key is the number of users who own it
+        // ('owned' values of both true and false are counted to
+        // include items lost on death)
+
+db.users.find().forEach(function(user) {
+    var owned = user.items.gear.owned;
+    for (var i=0, ic=itemsOfInterest.length; i<ic; i++) {
+        var itemKey = itemsOfInterest[i];
+        if (itemKey in owned) {
+            itemsFound[itemKey] = (itemsFound[itemKey] || 0) + 1;
+            // print(user.auth.local.username + ":  " + itemKey); // good for testing, bad for privacy
+        }
+    }
+});
+
+
+function yyyymmdd(date) {
+    var yyyy =  date.getFullYear().toString();
+    var mm   = (date.getMonth()+1).toString();
+    var dd   =  date.getDate().toString();
+    return yyyy + "-" + (mm[1]?mm:"0"+mm[0]) + "-" + (dd[1]?dd:"0"+dd[0]);
+}
+var today = yyyymmdd(new Date());
+
+var header = '"date"'; // heading row in CSV data
+var data   = '"' + today + '"'; // data row in CSV data
+for (var i=0, ic=itemsOfInterest.length; i<ic; i++) {
+    var itemKey = itemsOfInterest[i];
+    header += ',"' + itemKey + '"';
+    data += ',"' + (itemsFound[itemKey] || 0) + '"';
+}
+
+print("\nCSV DATA:\n");
+print(header);
+print(data);
+print("\nREADABLE DATA:\n");
+print(today);
+print(JSON.stringify(itemsFound, null, "  "));
+print("\n");
+
+
+/*  SAMPLE OUTPUT:
+> load("count_users_who_own_specified_gear.js")
+
+CSV DATA:
+
+"date","headAccessory_special_wondercon_red","headAccessory_special_wondercon_black","back_special_wondercon_black","back_special_wondercon_red","body_special_wondercon_red","body_special_wondercon_black","body_special_wondercon_gold"
+"2014-08-17","5","4","3","3","3","3","3"
+
+READABLE DATA:
+
+2014-08-17
+{
+  "headAccessory_special_wondercon_red": 5,
+  "headAccessory_special_wondercon_black": 4,
+  "back_special_wondercon_black": 3,
+  "back_special_wondercon_red": 3,
+  "body_special_wondercon_red": 3,
+  "body_special_wondercon_black": 3,
+  "body_special_wondercon_gold": 3
+}
+
+
+true
+> 
+*/