Improve error reporting in format()

Clarify invalid format conversion type error message and add hint.

Author: Jim Nasby

diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index f61e41ed7f18d49789ab29395ea16f8143c0256a..94599cc508fc108e112e4095b5e6a493e5a17fb9 100644 (file)
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -4788,7 +4788,8 @@ text_reverse(PG_FUNCTION_ARGS)
                if (++(ptr) >= (end_ptr)) \
                        ereport(ERROR, \
                                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE), \
-                                        errmsg("unterminated format specifier"))); \
+                                        errmsg("unterminated format() type specifier"), \
+                                        errhint("For a single \"%%\" use \"%%%%\"."))); \
        } while (0)
 
 /*
@@ -4920,8 +4921,9 @@ text_format(PG_FUNCTION_ARGS)
                if (strchr("sIL", *cp) == NULL)
                        ereport(ERROR,
                                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-                                        errmsg("unrecognized conversion type specifier \"%c\"",
-                                                       *cp)));
+                                        errmsg("unrecognized format() type specifier \"%c\"",
+                                                       *cp),
+                                        errhint("For a single \"%%\" use \"%%%%\".")));
 
                /* If indirect width was specified, get its value */
                if (widthpos >= 0)
@@ -4932,7 +4934,7 @@ text_format(PG_FUNCTION_ARGS)
                        if (arg >= nargs)
                                ereport(ERROR,
                                                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-                                                errmsg("too few arguments for format")));
+                                                errmsg("too few arguments for format()")));
 
                        /* Get the value and type of the selected argument */
                        if (!funcvariadic)
@@ -5040,8 +5042,9 @@ text_format(PG_FUNCTION_ARGS)
                                /* should not get here, because of previous check */
                                ereport(ERROR,
                                                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-                                         errmsg("unrecognized conversion type specifier \"%c\"",
-                                                        *cp)));
+                                         errmsg("unrecognized format() type specifier \"%c\"",
+                                                        *cp),
+                                         errhint("For a single \"%%\" use \"%%%%\".")));
                                break;
                }
        }

diff --git a/src/test/regress/expected/text.out b/src/test/regress/expected/text.out
index 1587046d95aec566b7ad6cc6bc9d7c3b5a40f7a7..a74b9cebd6c49161ea951ce248e718bac35ee2d6 100644 (file)
--- a/src/test/regress/expected/text.out
+++ b/src/test/regress/expected/text.out
@@ -211,7 +211,8 @@ ERROR:  too few arguments for format
 select format('Hello %s');
 ERROR:  too few arguments for format
 select format('Hello %x', 20);
-ERROR:  unrecognized conversion type specifier "x"
+ERROR:  unrecognized format() type specifier "x"
+HINT:  For a single "%" use "%%".
 -- check literal and sql identifiers
 select format('INSERT INTO %I VALUES(%L,%L)', 'mytab', 10, 'Hello');
                  format                 
@@ -263,9 +264,11 @@ ERROR:  format specifies argument 0, but arguments are numbered from 1
 select format('%*0$s', 'Hello');
 ERROR:  format specifies argument 0, but arguments are numbered from 1
 select format('%1$', 1);
-ERROR:  unterminated format specifier
+ERROR:  unterminated format() type specifier
+HINT:  For a single "%" use "%%".
 select format('%1$1', 1);
-ERROR:  unterminated format specifier
+ERROR:  unterminated format() type specifier
+HINT:  For a single "%" use "%%".
 -- check mix of positional and ordered placeholders
 select format('Hello %s %1$s %s', 'World', 'Hello again');
             format