Add esc(std::string_view).

Fixes #295.

I guess I meant to do this before, but forgot!  The overload was there
on `connection` but not on `transaction_base`.

NEWS

@@ -1,6 +1,7 @@
 7.0.5
  - Compile fix for g++ 10: include `<limits>` (#292).
  - Cleaned up error-checking of PG results.  (#280).
+ - The `esc()` methods now also take `std::string_view` (#295).
 7.0.4
  - Fix possible crash in `connection::connection_string` (#290).
  - Fix filtering of default values in `connection::connection_string` (#288).

include/pqxx/transaction_base.hxx

@@ -129,21 +129,26 @@ public:
    * @ingroup escaping-functions
    */
   //@{
-  /// Escape string for use as SQL string literal in this transaction
+  /// Escape string for use as SQL string literal in this transaction.
   [[nodiscard]] std::string esc(char const text[]) const
   {
     return conn().esc(text);
   }
-  /// Escape string for use as SQL string literal in this transaction
+  /// Escape string for use as SQL string literal in this transaction.
   [[nodiscard]] std::string esc(char const text[], size_t maxlen) const
   {
     return conn().esc(text, maxlen);
   }
-  /// Escape string for use as SQL string literal in this transaction
+  /// Escape string for use as SQL string literal in this transaction.
   [[nodiscard]] std::string esc(std::string const &text) const
   {
     return conn().esc(text);
   }
+  /// Escape string for use as SQL string literal in this transaction.
+  [[nodiscard]] std::string esc(std::string_view text) const
+  {
+    return conn().esc(text);
+  }
 
   /// Escape binary data for use as SQL string literal in this transaction
   /** Raw, binary data is treated differently from regular strings.  Binary

test/unit/test_escape.cxx

@@ -32,6 +32,8 @@ void test_esc(pqxx::connection_base &c, pqxx::transaction_base &t)
 {
   PQXX_CHECK_EQUAL(t.esc("", 0), "", "Empty string doesn't escape properly.");
   PQXX_CHECK_EQUAL(t.esc("'", 1), "''", "Single quote escaped incorrectly.");
+  PQXX_CHECK_EQUAL(
+    t.esc(std::string_view{"hello"}), "hello", "Trivial escape went wrong.");
   char const *const escstrings[]{"x", " ", "", nullptr};
   for (size_t i{0}; escstrings[i] != nullptr; ++i)
     compare_esc(c, t, escstrings[i]);