Resolve issue #4: Improve the value data type handling in the add fun…

…ction, add a value_type function to make it easier to see the collection type and make the README more clear how types are handled with subscripts.

README.md

@@ -83,6 +83,7 @@ CREATE EXTENSION collection;
 | values_to_table(collection, anyelement) | SETOF anyelement        | Returns all of the values as anyelement in the collection                                  |
 | to_table(collection)                    | TABLE(text, text)       | Returns all of the keys and values as text in the collection                               |
 | to_table(collection, anyelement)        | TABLE(text, anyelement) | Returns all of the keys and values as anyelement in the collection                         |
+| value_type(collection)                  | regtype                 | Returns the data type of the elements within the collection                                |
 
 ## Using Subscripts
 
@@ -125,7 +126,9 @@ The default type of a collection's element is `text`, however it can contain
 any valid PostgreSQL type. The type can be set in two ways. The first is by
 explicitly setting it as the type modifier when declaring the collection. If
 no type modifier is defined, the type of the first element added to the 
-collection will define the type of the collection.
+collection using the `add` function will define the type of the collection.
+If no type modifier is set, any subscript assignments or fetches will be cast
+to type `text`.
 
 ```sql
 DO 

sql/collection--0.9.sql

@@ -157,6 +157,11 @@ CREATE FUNCTION to_table(collection, anyelement, OUT key text, OUT value anyelem
   AS 'MODULE_PATHNAME', 'collection_to_table'
   LANGUAGE c;
 
+CREATE FUNCTION value_type(collection)
+  RETURNS regtype
+  AS 'MODULE_PATHNAME', 'collection_value_type'
+  LANGUAGE c;
+
 CREATE FUNCTION collection_stats(OUT add int8, OUT context_switch int8, 
                                  OUT delete int8, OUT find int8, OUT sort int8)
   AS 'MODULE_PATHNAME', 'collection_stats'

src/collection_io.c

@@ -20,6 +20,7 @@
 
 #include "catalog/pg_type.h"
 #include "common/jsonapi.h"
+#include "parser/parse_coerce.h"
 #include "pgstat.h"
 #include "utils/builtins.h"
 #include "utils/datum.h"
@@ -184,24 +185,26 @@ Datum
 collection_cast(PG_FUNCTION_ARGS)
 {
 	CollectionHeader *colhdr;
-	int32		typmod = PG_GETARG_INT32(1);
+	Oid			typmod = PG_GETARG_INT32(1);
 
 	colhdr = fetch_collection(fcinfo, 0);
 
 	pgstat_report_wait_start(collection_we_cast);
 
 	if (typmod > 0 && colhdr->value_type != InvalidOid)
 	{
-		Oid			value_type = typmod;
-
-		if (colhdr->value_type != value_type)
+		/*
+		 * Check if the cast is into a collection or if it can be coerced to
+		 * the appropriate type
+		 */
+		if (get_fn_expr_argtype(fcinfo->flinfo, 0) != typmod &&
+			!can_coerce_type(1, &colhdr->value_type, &typmod, COERCION_IMPLICIT))
 			ereport(ERROR,
 					(errcode(ERRCODE_DATATYPE_MISMATCH),
 					 errmsg("Incompatible value data type"),
 					 errdetail("Expecting %s, but received %s",
-							   format_type_extended(value_type, -1, 0),
+							   format_type_extended(typmod, -1, 0),
 							   format_type_extended(colhdr->value_type, -1, 0))));
-
 	}
 
 	pgstat_report_wait_end();

src/collection_subs.c

@@ -97,8 +97,6 @@ collection_subscript_transform(SubscriptingRef *sbsref,
 		sbsref->refrestype = TEXTOID;
 	else
 		sbsref->refrestype = sbsref->reftypmod;
-
-	sbsref->reftypmod = -1;
 }
 
 /*
@@ -114,6 +112,7 @@ collection_subscript_fetch(ExprState *state,
 						   ExprContext *econtext)
 {
 	SubscriptingRefState *sbsrefstate = op->d.sbsref.state;
+	CollectionSubWorkspace *workspace = (CollectionSubWorkspace *) sbsrefstate->workspace;
 	CollectionHeader *colhdr;
 	collection *item;
 	char	   *key;
@@ -141,8 +140,30 @@ collection_subscript_fetch(ExprState *state,
 	if (item == NULL)
 		value = (Datum) 0;
 	else
-		value = datumCopy(item->value, colhdr->value_byval, colhdr->value_type_len);
-
+	{
+		if (can_coerce_type(1, &workspace->value_type, &colhdr->value_type, COERCION_IMPLICIT))
+			value = datumCopy(item->value, colhdr->value_byval, colhdr->value_type_len);
+		else
+		{
+			if (workspace->value_type == TEXTOID)
+			{
+				bool		typisvarlena;
+				Oid			outfuncoid;
+
+				getTypeOutputInfo(colhdr->value_type, &outfuncoid, &typisvarlena);
+				value = CStringGetTextDatum(DatumGetCString(OidFunctionCall1(outfuncoid, item->value)));
+			}
+			else
+			{
+				ereport(ERROR,
+						(errcode(ERRCODE_DATATYPE_MISMATCH),
+						 errmsg("Incompatible value data type"),
+						 errdetail("Expecting %s, but received %s",
+								   format_type_extended(workspace->value_type, -1, 0),
+								   format_type_extended(colhdr->value_type, -1, 0))));
+			}
+		}
+	}
 
 	if (value == (Datum) 0)
 		*op->resnull = true;
@@ -185,6 +206,10 @@ collection_subscript_assign(ExprState *state,
 	{
 		colhdr = construct_empty_collection(CurrentMemoryContext);
 		*op->resnull = false;
+
+		colhdr->value_type = workspace->value_type;
+		colhdr->value_type_len = workspace->value_type_len;
+		colhdr->value_byval = workspace->value_byval;
 	}
 	else
 	{
@@ -193,6 +218,17 @@ collection_subscript_assign(ExprState *state,
 
 	pgstat_report_wait_start(collection_we_assign);
 
+	if (!can_coerce_type(1, &workspace->value_type, &colhdr->value_type, COERCION_IMPLICIT))
+	{
+		pgstat_report_wait_end();
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+				 errmsg("incompatible value data type"),
+				 errdetail("expecting %s, but received %s",
+						   format_type_extended(colhdr->value_type, -1, 0),
+						   format_type_extended(workspace->value_type, -1, 0))));
+	}
+
 	oldcxt = MemoryContextSwitchTo(colhdr->hdr.eoh_context);
 
 	key = text_to_cstring(DatumGetTextPP(sbsrefstate->upperindex[0]));
@@ -203,10 +239,6 @@ collection_subscript_assign(ExprState *state,
 
 	HASH_REPLACE(hh, colhdr->current, key[0], strlen(key), item, replaced_item);
 
-	colhdr->value_type = workspace->value_type;
-	colhdr->value_type_len = workspace->value_type_len;
-	colhdr->value_byval = workspace->value_byval;
-
 	if (colhdr->head == NULL)
 		colhdr->head = colhdr->current;
 
@@ -240,7 +272,7 @@ collection_exec_setup(const SubscriptingRef *sbsref,
 	workspace = (CollectionSubWorkspace *) palloc(sizeof(CollectionSubWorkspace));
 	sbsrefstate->workspace = workspace;
 
-	/* Default to storing text unless the typmod is set */
+	/* Default to fetching as text unless the typmod is set */
 	if (sbsref->reftypmod == -1)
 	{
 		workspace->value_type = TEXTOID;

src/collection_userfuncs.c

@@ -51,6 +51,7 @@ PG_FUNCTION_INFO_V1(collection_keys_to_table);
 PG_FUNCTION_INFO_V1(collection_values_to_table);
 PG_FUNCTION_INFO_V1(collection_to_table);
 
+PG_FUNCTION_INFO_V1(collection_value_type);
 PG_FUNCTION_INFO_V1(collection_stats);
 PG_FUNCTION_INFO_V1(collection_stats_reset);
 
@@ -88,16 +89,35 @@ collection_add(PG_FUNCTION_ARGS)
 	argtype = get_fn_expr_argtype(fcinfo->flinfo, 2);
 	get_typlenbyval(argtype, &argtypelen, &argtypebyval);
 
+	/*
+	 * Set the value type of the collection to the first element added
+	 */
+	if (colhdr->value_type == InvalidOid)
+	{
+		colhdr->value_type = argtype;
+		colhdr->value_type_len = argtypelen;
+		colhdr->value_byval = argtypebyval;
+	}
+	else
+	{
+		if (!can_coerce_type(1, &argtype, &colhdr->value_type, COERCION_IMPLICIT))
+		{
+			pgstat_report_wait_end();
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("incompatible value data type"),
+					 errdetail("expecting %s, but received %s",
+							   format_type_extended(colhdr->value_type, -1, 0),
+							   format_type_extended(argtype, -1, 0))));
+		}
+	}
+
 	item = (collection *) palloc(sizeof(collection));
 	item->key = key;
 	item->value = datumCopy(value, argtypebyval, argtypelen);
 
 	HASH_REPLACE(hh, colhdr->current, key[0], strlen(key), item, replaced_item);
 
-	colhdr->value_type = argtype;
-	colhdr->value_type_len = argtypelen;
-	colhdr->value_byval = argtypebyval;
-
 	if (colhdr->head == NULL)
 		colhdr->head = colhdr->current;
 
@@ -589,6 +609,19 @@ collection_to_table(PG_FUNCTION_ARGS)
 	}
 }
 
+Datum
+collection_value_type(PG_FUNCTION_ARGS)
+{
+	CollectionHeader *colhdr;
+
+	colhdr = fetch_collection(fcinfo, 0);
+
+	if (colhdr->head == NULL || colhdr->value_type == InvalidOid)
+		PG_RETURN_NULL();
+
+	PG_RETURN_OID(colhdr->value_type);
+}
+
 Datum
 collection_stats(PG_FUNCTION_ARGS)
 {

test/expected/collection.out

@@ -396,3 +396,44 @@ SELECT * FROM collections_test ORDER BY c1;
 (2 rows)
 
 DROP TABLE collections_test;
+DO
+$$
+DECLARE
+  t  collection;
+BEGIN
+  RAISE NOTICE 'Test 23';
+  t := add(t, '1', 111::bigint);
+  t := add(t, '2', 222::bigint);
+  RAISE NOTICE 'The current val is %', value(t, null::bigint);
+  RAISE NOTICE 'The current value type is %', pg_typeof(value(t, null::bigint));
+END
+$$;
+NOTICE:  Test 23
+NOTICE:  The current val is 111
+NOTICE:  The current value type is bigint
+DO
+$$
+DECLARE
+  t  collection;
+BEGIN
+  RAISE NOTICE 'Test 24';
+  t := add(t, '1', 111::bigint);
+  t := add(t, '2', 'hello'::text);
+END
+$$;
+NOTICE:  Test 24
+ERROR:  incompatible value data type
+DETAIL:  expecting bigint, but received text
+CONTEXT:  PL/pgSQL function inline_code_block line 7 at assignment
+DO
+$$
+DECLARE
+  t  collection;
+BEGIN
+  RAISE NOTICE 'Test 25';
+  t := add(t, '1', 111::bigint);
+  RAISE NOTICE 'The type is %', value_type(t);
+END
+$$;
+NOTICE:  Test 25
+NOTICE:  The type is bigint

test/expected/subscript.out

@@ -138,8 +138,8 @@ BEGIN
 END
 $$;
 NOTICE:  Subscript test 10
-ERROR:  Incompatible value data type
-DETAIL:  Expecting text, but received date
+ERROR:  incompatible value data type
+DETAIL:  expecting text, but received date
 CONTEXT:  PL/pgSQL function inline_code_block line 7 at assignment
 DO
 $$
@@ -176,3 +176,32 @@ END
 $$;
 NOTICE:  Subscript test 12
 NOTICE:  The current val is <NULL>
+DO
+$$
+DECLARE
+  t  collection;
+BEGIN
+  RAISE NOTICE 'Subscript test 13';
+
+  t['1'] := 111::bigint;
+  t['2'] := 222::bigint;
+  RAISE NOTICE 'The type is %', value_type(t);
+END
+$$;
+NOTICE:  Subscript test 13
+NOTICE:  The type is text
+DO
+$$
+DECLARE
+  t  collection;
+BEGIN
+  RAISE NOTICE 'Subscript test 14';
+
+  t := add(t, '1', 111::bigint);
+  t['2'] := 'abc';
+END
+$$;
+NOTICE:  Subscript test 14
+ERROR:  incompatible value data type
+DETAIL:  expecting bigint, but received text
+CONTEXT:  PL/pgSQL function inline_code_block line 8 at assignment

test/sql/collection.sql

@@ -327,3 +327,38 @@ INSERT INTO collections_test VALUES (2, add(null::collection, 'bbb', 'Hello ALL'
 SELECT * FROM collections_test ORDER BY c1;
 
 DROP TABLE collections_test;
+
+DO
+$$
+DECLARE
+  t  collection;
+BEGIN
+  RAISE NOTICE 'Test 23';
+  t := add(t, '1', 111::bigint);
+  t := add(t, '2', 222::bigint);
+  RAISE NOTICE 'The current val is %', value(t, null::bigint);
+  RAISE NOTICE 'The current value type is %', pg_typeof(value(t, null::bigint));
+END
+$$;
+
+DO
+$$
+DECLARE
+  t  collection;
+BEGIN
+  RAISE NOTICE 'Test 24';
+  t := add(t, '1', 111::bigint);
+  t := add(t, '2', 'hello'::text);
+END
+$$;
+
+DO
+$$
+DECLARE
+  t  collection;
+BEGIN
+  RAISE NOTICE 'Test 25';
+  t := add(t, '1', 111::bigint);
+  RAISE NOTICE 'The type is %', value_type(t);
+END
+$$;

test/sql/subscript.sql

@@ -158,3 +158,30 @@ BEGIN
   RAISE NOTICE 'The current val is %', t['2'];
 END
 $$;
+
+DO
+$$
+DECLARE
+  t  collection;
+BEGIN
+  RAISE NOTICE 'Subscript test 13';
+
+  t['1'] := 111::bigint;
+  t['2'] := 222::bigint;
+  RAISE NOTICE 'The type is %', value_type(t);
+END
+$$;
+
+
+DO
+$$
+DECLARE
+  t  collection;
+BEGIN
+  RAISE NOTICE 'Subscript test 14';
+
+  t := add(t, '1', 111::bigint);
+  t['2'] := 'abc';
+END
+$$;
+