Add For Buying and For Selling checkboxes in Currency Exchange
diff --git a/erpnext/public/js/controllers/transaction.js b/erpnext/public/js/controllers/transaction.js
index 2130d2b..7c1a42a 100644
--- a/erpnext/public/js/controllers/transaction.js
+++ b/erpnext/public/js/controllers/transaction.js
@@ -599,14 +599,13 @@
 		/* manqala 19/09/2016: let the translation date be whichever of the transaction_date or posting_date is available */
 		var transaction_date = this.frm.doc.transaction_date || this.frm.doc.posting_date;
 		/* end manqala */
-
 		var me = this;
 		this.set_dynamic_labels();
-
 		var company_currency = this.get_company_currency();
 		// Added `ignore_pricing_rule` to determine if document is loading after mapping from another doc
 		if(this.frm.doc.currency && this.frm.doc.currency !== company_currency
 				&& !this.frm.doc.ignore_pricing_rule) {
+
 			this.get_exchange_rate(transaction_date, this.frm.doc.currency, company_currency,
 				function(exchange_rate) {
 					me.frm.set_value("conversion_rate", exchange_rate);
@@ -668,13 +667,17 @@
 	},
 
 	get_exchange_rate: function(transaction_date, from_currency, to_currency, callback) {
+		if (this.frm.doctype == "Purchase Order") {
+			var args = "for_buying";
+		}
 		if (!transaction_date || !from_currency || !to_currency) return;
 		return frappe.call({
 			method: "erpnext.setup.utils.get_exchange_rate",
 			args: {
 				transaction_date: transaction_date,
 				from_currency: from_currency,
-				to_currency: to_currency
+				to_currency: to_currency,
+				args: args
 			},
 			callback: function(r) {
 				callback(flt(r.message));
diff --git a/erpnext/setup/doctype/currency_exchange/currency_exchange.json b/erpnext/setup/doctype/currency_exchange/currency_exchange.json
index 76e1a6b..89c3736 100644
--- a/erpnext/setup/doctype/currency_exchange/currency_exchange.json
+++ b/erpnext/setup/doctype/currency_exchange/currency_exchange.json
@@ -1,5 +1,6 @@
 {
  "allow_copy": 0, 
+ "allow_guest_to_view": 0, 
  "allow_import": 1, 
  "allow_rename": 0, 
  "beta": 0, 
@@ -13,6 +14,7 @@
  "engine": "InnoDB", 
  "fields": [
   {
+   "allow_bulk_edit": 0, 
    "allow_on_submit": 0, 
    "bold": 0, 
    "collapsible": 0, 
@@ -23,7 +25,9 @@
    "ignore_user_permissions": 0, 
    "ignore_xss_filter": 0, 
    "in_filter": 0, 
+   "in_global_search": 0, 
    "in_list_view": 1, 
+   "in_standard_filter": 0, 
    "label": "Date", 
    "length": 0, 
    "no_copy": 0, 
@@ -32,14 +36,17 @@
    "print_hide": 0, 
    "print_hide_if_no_value": 0, 
    "read_only": 0, 
+   "remember_last_selected_value": 0, 
    "report_hide": 0, 
    "reqd": 1, 
    "search_index": 0, 
    "set_only_once": 0, 
+   "translatable": 0, 
    "unique": 0, 
    "width": "5"
   }, 
   {
+   "allow_bulk_edit": 0, 
    "allow_on_submit": 0, 
    "bold": 0, 
    "collapsible": 0, 
@@ -50,6 +57,7 @@
    "ignore_user_permissions": 0, 
    "ignore_xss_filter": 0, 
    "in_filter": 0, 
+   "in_global_search": 0, 
    "in_list_view": 1, 
    "in_standard_filter": 1, 
    "label": "From Currency", 
@@ -65,10 +73,12 @@
    "reqd": 1, 
    "search_index": 0, 
    "set_only_once": 0, 
+   "translatable": 0, 
    "unique": 0, 
    "width": "3"
   }, 
   {
+   "allow_bulk_edit": 0, 
    "allow_on_submit": 0, 
    "bold": 0, 
    "collapsible": 0, 
@@ -79,6 +89,7 @@
    "ignore_user_permissions": 0, 
    "ignore_xss_filter": 0, 
    "in_filter": 0, 
+   "in_global_search": 0, 
    "in_list_view": 1, 
    "in_standard_filter": 1, 
    "label": "To Currency", 
@@ -94,10 +105,12 @@
    "reqd": 1, 
    "search_index": 0, 
    "set_only_once": 0, 
+   "translatable": 0, 
    "unique": 0, 
    "width": "3"
   }, 
   {
+   "allow_bulk_edit": 0, 
    "allow_on_submit": 0, 
    "bold": 0, 
    "collapsible": 0, 
@@ -108,6 +121,7 @@
    "ignore_user_permissions": 0, 
    "ignore_xss_filter": 0, 
    "in_filter": 0, 
+   "in_global_search": 0, 
    "in_list_view": 1, 
    "in_standard_filter": 0, 
    "label": "Exchange Rate", 
@@ -123,22 +137,117 @@
    "reqd": 1, 
    "search_index": 0, 
    "set_only_once": 0, 
+   "translatable": 0, 
    "unique": 0, 
    "width": "3"
+  }, 
+  {
+   "allow_bulk_edit": 0, 
+   "allow_on_submit": 0, 
+   "bold": 0, 
+   "collapsible": 0, 
+   "columns": 0, 
+   "fieldname": "column_break_5", 
+   "fieldtype": "Column Break", 
+   "hidden": 0, 
+   "ignore_user_permissions": 0, 
+   "ignore_xss_filter": 0, 
+   "in_filter": 0, 
+   "in_global_search": 0, 
+   "in_list_view": 0, 
+   "in_standard_filter": 0, 
+   "length": 0, 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "print_hide_if_no_value": 0, 
+   "read_only": 0, 
+   "remember_last_selected_value": 0, 
+   "report_hide": 0, 
+   "reqd": 0, 
+   "search_index": 0, 
+   "set_only_once": 0, 
+   "translatable": 0, 
+   "unique": 0
+  }, 
+  {
+   "allow_bulk_edit": 0, 
+   "allow_on_submit": 0, 
+   "bold": 0, 
+   "collapsible": 0, 
+   "columns": 0, 
+   "default": "1", 
+   "fieldname": "for_buying", 
+   "fieldtype": "Check", 
+   "hidden": 0, 
+   "ignore_user_permissions": 0, 
+   "ignore_xss_filter": 0, 
+   "in_filter": 0, 
+   "in_global_search": 0, 
+   "in_list_view": 0, 
+   "in_standard_filter": 0, 
+   "label": "For Buying", 
+   "length": 0, 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "print_hide_if_no_value": 0, 
+   "read_only": 0, 
+   "remember_last_selected_value": 0, 
+   "report_hide": 0, 
+   "reqd": 0, 
+   "search_index": 0, 
+   "set_only_once": 0, 
+   "translatable": 0, 
+   "unique": 0
+  }, 
+  {
+   "allow_bulk_edit": 0, 
+   "allow_on_submit": 0, 
+   "bold": 0, 
+   "collapsible": 0, 
+   "columns": 0, 
+   "default": "1", 
+   "fieldname": "for_selling", 
+   "fieldtype": "Check", 
+   "hidden": 0, 
+   "ignore_user_permissions": 0, 
+   "ignore_xss_filter": 0, 
+   "in_filter": 0, 
+   "in_global_search": 0, 
+   "in_list_view": 0, 
+   "in_standard_filter": 0, 
+   "label": "For Selling", 
+   "length": 0, 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "print_hide_if_no_value": 0, 
+   "read_only": 0, 
+   "remember_last_selected_value": 0, 
+   "report_hide": 0, 
+   "reqd": 0, 
+   "search_index": 0, 
+   "set_only_once": 0, 
+   "translatable": 0, 
+   "unique": 0
   }
  ], 
+ "has_web_view": 0, 
  "hide_heading": 0, 
  "hide_toolbar": 0, 
  "icon": "fa fa-exchange", 
  "idx": 1, 
  "image_view": 0, 
  "in_create": 0, 
- "in_dialog": 0, 
  "is_submittable": 0, 
  "issingle": 0, 
  "istable": 0, 
  "max_attachments": 0, 
- "modified": "2016-11-08 05:28:09.772560", 
+ "modified": "2018-05-15 11:23:35.639039", 
  "modified_by": "Administrator", 
  "module": "Setup", 
  "name": "Currency Exchange", 
@@ -146,7 +255,6 @@
  "permissions": [
   {
    "amend": 0, 
-   "apply_user_permissions": 0, 
    "cancel": 0, 
    "create": 1, 
    "delete": 1, 
@@ -154,7 +262,6 @@
    "export": 0, 
    "if_owner": 0, 
    "import": 0, 
-   "is_custom": 0, 
    "permlevel": 0, 
    "print": 1, 
    "read": 1, 
@@ -167,7 +274,6 @@
   }, 
   {
    "amend": 0, 
-   "apply_user_permissions": 0, 
    "cancel": 0, 
    "create": 0, 
    "delete": 0, 
@@ -175,7 +281,6 @@
    "export": 0, 
    "if_owner": 0, 
    "import": 0, 
-   "is_custom": 0, 
    "permlevel": 0, 
    "print": 1, 
    "read": 1, 
@@ -188,7 +293,6 @@
   }, 
   {
    "amend": 0, 
-   "apply_user_permissions": 0, 
    "cancel": 0, 
    "create": 0, 
    "delete": 0, 
@@ -196,7 +300,6 @@
    "export": 0, 
    "if_owner": 0, 
    "import": 0, 
-   "is_custom": 0, 
    "permlevel": 0, 
    "print": 1, 
    "read": 1, 
@@ -209,7 +312,6 @@
   }, 
   {
    "amend": 0, 
-   "apply_user_permissions": 0, 
    "cancel": 0, 
    "create": 0, 
    "delete": 0, 
@@ -217,7 +319,6 @@
    "export": 0, 
    "if_owner": 0, 
    "import": 0, 
-   "is_custom": 0, 
    "permlevel": 0, 
    "print": 1, 
    "read": 1, 
@@ -232,8 +333,10 @@
  "quick_entry": 1, 
  "read_only": 0, 
  "read_only_onload": 0, 
+ "show_name_in_global_search": 0, 
  "sort_field": "name", 
  "sort_order": "DESC", 
  "title_field": "", 
+ "track_changes": 0, 
  "track_seen": 0
 }
\ No newline at end of file
diff --git a/erpnext/setup/doctype/currency_exchange/currency_exchange.py b/erpnext/setup/doctype/currency_exchange/currency_exchange.py
index ab892fb..4effb5a 100644
--- a/erpnext/setup/doctype/currency_exchange/currency_exchange.py
+++ b/erpnext/setup/doctype/currency_exchange/currency_exchange.py
@@ -5,9 +5,9 @@
 
 from __future__ import unicode_literals
 import frappe
-from frappe import _
+from frappe import _, throw
 from frappe.model.document import Document
-from frappe.utils import get_datetime_str, formatdate, nowdate
+from frappe.utils import get_datetime_str, formatdate, nowdate, cint
 
 class CurrencyExchange(Document):
 	def autoname(self):
@@ -20,4 +20,7 @@
 		self.validate_value("exchange_rate", ">", 0)
 
 		if self.from_currency == self.to_currency:
-			frappe.throw(_("From Currency and To Currency cannot be same"))
+			throw(_("From Currency and To Currency cannot be same"))
+
+		if not cint(self.for_buying) and not cint(self.for_selling):
+			throw(_("Currency Exchange must be applicable for Buying or for Selling."))
\ No newline at end of file
diff --git a/erpnext/setup/doctype/currency_exchange/test_currency_exchange.js b/erpnext/setup/doctype/currency_exchange/test_currency_exchange.js
new file mode 100644
index 0000000..19fde2e
--- /dev/null
+++ b/erpnext/setup/doctype/currency_exchange/test_currency_exchange.js
@@ -0,0 +1,23 @@
+/* eslint-disable */
+// rename this file from _test_[name] to test_[name] to activate
+// and remove above this line
+
+QUnit.test("test: Currency Exchange", function (assert) {
+	let done = assert.async();
+
+	// number of asserts
+	assert.expect(1);
+
+	frappe.run_serially([
+		// insert a new Currency Exchange
+		() => frappe.tests.make('Currency Exchange', [
+			// values to be set
+			{key: 'value'}
+		]),
+		() => {
+			assert.equal(cur_frm.doc.key, 'value');
+		},
+		() => done()
+	]);
+
+});
diff --git a/erpnext/setup/utils.py b/erpnext/setup/utils.py
index 8d9bba3..04c9931 100644
--- a/erpnext/setup/utils.py
+++ b/erpnext/setup/utils.py
@@ -55,7 +55,7 @@
 	frappe.db.commit()
 
 @frappe.whitelist()
-def get_exchange_rate(from_currency, to_currency, transaction_date=None):
+def get_exchange_rate(from_currency, to_currency, transaction_date=None, args=None):
 	if not (from_currency and to_currency):
 		# manqala 19/09/2016: Should this be an empty return or should it throw and exception?
 		return
@@ -74,7 +74,12 @@
 		["from_currency", "=", from_currency],
 		["to_currency", "=", to_currency]
 	]
-
+	frappe.errprint(args)
+	if args == "for_buying":
+		filters.append(["for_buying", "=", "1"])
+	elif args == "for_selling":
+		filters.append(["for_selling", "=", 1])
+	frappe.errprint(filters)
 	if not allow_stale_rates:
 		stale_days = currency_settings.get("stale_days")
 		checkpoint_date = add_days(transaction_date, -stale_days)
@@ -84,7 +89,6 @@
 	entries = frappe.get_all(
 		"Currency Exchange", fields=["exchange_rate"], filters=filters, order_by="date desc",
 		limit=1)
-
 	if entries:
 		return flt(entries[0].exchange_rate)