Implement various jsonpath methods

This commit implements ithe jsonpath .bigint(), .boolean(),
.date(), .decimal([precision [, scale]]), .integer(), .number(),
.string(), .time(), .time_tz(), .timestamp(), and .timestamp_tz()
methods.

.bigint() converts the given JSON string or a numeric value to
the bigint type representation.

.boolean() converts the given JSON string, numeric, or boolean
value to the boolean type representation.  In the numeric case, only
integers are allowed. We use the parse_bool() backend function
to convert a string to a bool.

.decimal([precision [, scale]]) converts the given JSON string
or a numeric value to the numeric type representation.  If precision
and scale are provided for .decimal(), then it is converted to the
equivalent numeric typmod and applied to the numeric number.

.integer() and .number() convert the given JSON string or a
numeric value to the int4 and numeric type representation.

.string() uses the datatype's output function to convert numeric
and various date/time types to the string representation.

The JSON string representing a valid date/time is converted to the
specific date or time type representation using jsonpath .date(),
.time(), .time_tz(), .timestamp(), .timestamp_tz() methods.  The
changes use the infrastructure of the .datetime() method and perform
the datatype conversion as appropriate.  Unlike the .datetime()
method, none of these methods accept a format template and use ISO
DateTime format instead.  However, except for .date(), the
date/time related methods take an optional precision to adjust the
fractional seconds.

Jeevan Chalke, reviewed by Peter Eisentraut and Andrew Dunstan.

1 files changed, 218 insertions, 0 deletions

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 968e8d59fb5..11d62ba5949 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -17728,6 +17728,38 @@ strict $.**.HR
 
       <row>
        <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>value</replaceable> <literal>.</literal> <literal>boolean()</literal>
+        <returnvalue><replaceable>boolean</replaceable></returnvalue>
+       </para>
+       <para>
+        Boolean value converted from a JSON boolean, number, or string
+       </para>
+       <para>
+        <literal>jsonb_path_query_array('[1, "yes", false]', '$[*].boolean()')</literal>
+        <returnvalue>[true, true, false]</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>value</replaceable> <literal>.</literal> <literal>string()</literal>
+        <returnvalue><replaceable>string</replaceable></returnvalue>
+       </para>
+       <para>
+        String value converted from a JSON boolean, number, string, or datetime
+       </para>
+       <para>
+        <literal>jsonb_path_query_array('[1.23, "xyz", false]', '$[*].string()')</literal>
+        <returnvalue>["1.23", "xyz", "false"]</returnvalue>
+       </para>
+       <para>
+        <literal>jsonb_path_query('"2023-08-15"', '$.datetime().string()')</literal>
+        <returnvalue>"2023-08-15"</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
         <replaceable>value</replaceable> <literal>.</literal> <literal>double()</literal>
         <returnvalue><replaceable>number</replaceable></returnvalue>
        </para>
@@ -17785,6 +17817,62 @@ strict $.**.HR
 
       <row>
        <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>value</replaceable> <literal>.</literal> <literal>bigint()</literal>
+        <returnvalue><replaceable>bigint</replaceable></returnvalue>
+       </para>
+       <para>
+        Big integer value converted from a JSON number or string
+       </para>
+       <para>
+        <literal>jsonb_path_query('{"len": "9876543219"}', '$.len.bigint()')</literal>
+        <returnvalue>9876543219</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>value</replaceable> <literal>.</literal> <literal>decimal( [ <replaceable>precision</replaceable> [ , <replaceable>scale</replaceable> ] ] )</literal>
+        <returnvalue><replaceable>decimal</replaceable></returnvalue>
+       </para>
+       <para>
+        Rounded decimal value converted from a JSON number or string. <literal>precision</literal> and <literal>scale</literal> must be integer values.
+       </para>
+       <para>
+        <literal>jsonb_path_query('1234.5678', '$.decimal(6, 2)')</literal>
+        <returnvalue>1234.57</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>value</replaceable> <literal>.</literal> <literal>integer()</literal>
+        <returnvalue><replaceable>integer</replaceable></returnvalue>
+       </para>
+       <para>
+        Integer value converted from a JSON number or string
+       </para>
+       <para>
+        <literal>jsonb_path_query('{"len": "12345"}', '$.len.integer()')</literal>
+        <returnvalue>12345</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>value</replaceable> <literal>.</literal> <literal>number()</literal>
+        <returnvalue><replaceable>numeric</replaceable></returnvalue>
+       </para>
+       <para>
+        Numeric value converted from a JSON number or string
+       </para>
+       <para>
+        <literal>jsonb_path_query('{"len": "123.45"}', '$.len.number()')</literal>
+        <returnvalue>123.45</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
         <replaceable>string</replaceable> <literal>.</literal> <literal>datetime()</literal>
         <returnvalue><replaceable>datetime_type</replaceable></returnvalue>
         (see note)
@@ -17816,6 +17904,136 @@ strict $.**.HR
 
       <row>
        <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>string</replaceable> <literal>.</literal> <literal>date()</literal>
+        <returnvalue><replaceable>date</replaceable></returnvalue>
+       </para>
+       <para>
+        Date value converted from a string
+       </para>
+       <para>
+        <literal>jsonb_path_query('"2023-08-15"', '$.date()')</literal>
+        <returnvalue>"2023-08-15"</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>string</replaceable> <literal>.</literal> <literal>time()</literal>
+        <returnvalue><replaceable>time without time zone</replaceable></returnvalue>
+       </para>
+       <para>
+        Time without time zone value converted from a string
+       </para>
+       <para>
+        <literal>jsonb_path_query('"12:34:56"', '$.time()')</literal>
+        <returnvalue>"12:34:56"</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>string</replaceable> <literal>.</literal> <literal>time(<replaceable>precision</replaceable>)</literal>
+        <returnvalue><replaceable>time without time zone</replaceable></returnvalue>
+       </para>
+       <para>
+        Time without time zone value converted from a string, with fractional
+        seconds adjusted to the given precision.
+       </para>
+       <para>
+        <literal>jsonb_path_query('"12:34:56.789"', '$.time(2)')</literal>
+        <returnvalue>"12:34:56.79"</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>string</replaceable> <literal>.</literal> <literal>time_tz()</literal>
+        <returnvalue><replaceable>time with time zone</replaceable></returnvalue>
+       </para>
+       <para>
+        Time with time zone value converted from a string
+       </para>
+       <para>
+        <literal>jsonb_path_query('"12:34:56 +05:30"', '$.time_tz()')</literal>
+        <returnvalue>"12:34:56+05:30"</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>string</replaceable> <literal>.</literal> <literal>time_tz(<replaceable>precision</replaceable>)</literal>
+        <returnvalue><replaceable>time with time zone</replaceable></returnvalue>
+       </para>
+       <para>
+        Time with time zone value converted from a string, with fractional
+        seconds adjusted to the given precision.
+       </para>
+       <para>
+        <literal>jsonb_path_query('"12:34:56.789 +05:30"', '$.time_tz(2)')</literal>
+        <returnvalue>"12:34:56.79+05:30"</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>string</replaceable> <literal>.</literal> <literal>timestamp()</literal>
+        <returnvalue><replaceable>timestamp without time zone</replaceable></returnvalue>
+       </para>
+       <para>
+        Timestamp without time zone value converted from a string
+       </para>
+       <para>
+        <literal>jsonb_path_query('"2023-08-15 12:34:56"', '$.timestamp()')</literal>
+        <returnvalue>"2023-08-15T12:34:56"</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>string</replaceable> <literal>.</literal> <literal>timestamp(<replaceable>precision</replaceable>)</literal>
+        <returnvalue><replaceable>timestamp without time zone</replaceable></returnvalue>
+       </para>
+       <para>
+        Timestamp without time zone value converted from a string, with
+        fractional seconds adjusted to the given precision.
+       </para>
+       <para>
+        <literal>jsonb_path_query('"2023-08-15 12:34:56.789"', '$.timestamp(2)')</literal>
+        <returnvalue>"2023-08-15T12:34:56.79"</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>string</replaceable> <literal>.</literal> <literal>timestamp_tz()</literal>
+        <returnvalue><replaceable>timestamp with time zone</replaceable></returnvalue>
+       </para>
+       <para>
+        Timestamp with time zone value converted from a string
+       </para>
+       <para>
+        <literal>jsonb_path_query('"2023-08-15 12:34:56 +05:30"', '$.timestamp_tz()')</literal>
+        <returnvalue>"2023-08-15T12:34:56+05:30"</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
+        <replaceable>string</replaceable> <literal>.</literal> <literal>timestamp_tz(<replaceable>precision</replaceable>)</literal>
+        <returnvalue><replaceable>timestamp with time zone</replaceable></returnvalue>
+       </para>
+       <para>
+        Timestamp with time zone value converted from a string, with fractional
+        seconds adjusted to the given precision.
+       </para>
+       <para>
+        <literal>jsonb_path_query('"2023-08-15 12:34:56.789 +05:30"', '$.timestamp_tz(2)')</literal>
+        <returnvalue>"2023-08-15T12:34:56.79+05:30"</returnvalue>
+       </para></entry>
+      </row>
+
+      <row>
+       <entry role="func_table_entry"><para role="func_signature">
         <replaceable>object</replaceable> <literal>.</literal> <literal>keyvalue()</literal>
         <returnvalue><replaceable>array</replaceable></returnvalue>
        </para>