fix: only make fetch_from field read only if no input (backport #19192)…

… (#19194)

* fix: only make fetch_from field read only if no input (#19192)

(cherry picked from commit 7578be8)

* chore: v13 js compatibility

Co-authored-by: Ankush Menat <ankush@frappe.io>

frappe/public/js/frappe/form/controls/base_input.js

@@ -50,6 +50,16 @@ frappe.ui.form.ControlInput = frappe.ui.form.Control.extend({
 		}
 	},
 
+	read_only_because_of_fetch_from() {
+		return (
+			this.df.fetch_from &&
+			!this.df.fetch_if_empty &&
+			this.frm &&
+			this.frm.doc &&
+			this.frm.doc[this.df.fetch_from.split(".")[0]]
+		);
+	},
+
 	// update input value, label, description
 	// display (show/hide/read-only),
 	// mandatory style on refresh
@@ -80,7 +90,7 @@ frappe.ui.form.ControlInput = frappe.ui.form.Control.extend({
 				me.value = me.doc[me.df.fieldname];
 			}
 
-			let is_fetch_from_read_only = me.df.fetch_from && !me.df.fetch_if_empty;
+			let is_fetch_from_read_only = me.read_only_because_of_fetch_from();
 
 			if (me.can_write() && !is_fetch_from_read_only) {
 				me.disp_area && $(me.disp_area).toggle(false);