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authorAmit Langote <amitlan@postgresql.org>2024-03-21 17:06:27 +0900
committerAmit Langote <amitlan@postgresql.org>2024-03-21 17:07:03 +0900
commit6185c9737cf48c9540782d88f12bd2912d6ca1cc (patch)
tree60b88a5d63fc61a1dbb11c5459ad83273f93db77 /src/backend/parser/parse_expr.c
parenta145f424d5248a09d766e8cb503b999290cb3b31 (diff)
downloadpostgresql-6185c9737cf48c9540782d88f12bd2912d6ca1cc.tar.gz
postgresql-6185c9737cf48c9540782d88f12bd2912d6ca1cc.zip
Add SQL/JSON query functions
This introduces the following SQL/JSON functions for querying JSON data using jsonpath expressions: JSON_EXISTS(), which can be used to apply a jsonpath expression to a JSON value to check if it yields any values. JSON_QUERY(), which can be used to to apply a jsonpath expression to a JSON value to get a JSON object, an array, or a string. There are various options to control whether multi-value result uses array wrappers and whether the singleton scalar strings are quoted or not. JSON_VALUE(), which can be used to apply a jsonpath expression to a JSON value to return a single scalar value, producing an error if it multiple values are matched. Both JSON_VALUE() and JSON_QUERY() functions have options for handling EMPTY and ERROR conditions, which can be used to specify the behavior when no values are matched and when an error occurs during jsonpath evaluation, respectively. Author: Nikita Glukhov <n.gluhov@postgrespro.ru> Author: Teodor Sigaev <teodor@sigaev.ru> Author: Oleg Bartunov <obartunov@gmail.com> Author: Alexander Korotkov <aekorotkov@gmail.com> Author: Andrew Dunstan <andrew@dunslane.net> Author: Amit Langote <amitlangote09@gmail.com> Author: Peter Eisentraut <peter@eisentraut.org> Author: Jian He <jian.universality@gmail.com> Reviewers have included (in no particular order): Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby, Álvaro Herrera, Jian He, Anton A. Melnikov, Nikita Malakhov, Peter Eisentraut, Tomas Vondra Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru Discussion: https://postgr.es/m/20220616233130.rparivafipt6doj3@alap3.anarazel.de Discussion: https://postgr.es/m/abd9b83b-aa66-f230-3d6d-734817f0995d%40postgresql.org Discussion: https://postgr.es/m/CA+HiwqHROpf9e644D8BRqYvaAPmgBZVup-xKMDPk-nd4EpgzHw@mail.gmail.com Discussion: https://postgr.es/m/CA+HiwqE4XTdfb1nW=Ojoy_tQSRhYt-q_kb6i5d4xcKyrLC1Nbg@mail.gmail.com
Diffstat (limited to 'src/backend/parser/parse_expr.c')
-rw-r--r--src/backend/parser/parse_expr.c553
1 files changed, 540 insertions, 13 deletions
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index d44b1f2ab2f..7166138bf76 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -37,6 +37,7 @@
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/fmgroids.h"
+#include "utils/jsonb.h"
#include "utils/lsyscache.h"
#include "utils/timestamp.h"
#include "utils/xml.h"
@@ -91,6 +92,15 @@ static Node *transformJsonParseExpr(ParseState *pstate, JsonParseExpr *expr);
static Node *transformJsonScalarExpr(ParseState *pstate, JsonScalarExpr *expr);
static Node *transformJsonSerializeExpr(ParseState *pstate,
JsonSerializeExpr *expr);
+static Node *transformJsonFuncExpr(ParseState *pstate, JsonFuncExpr *p);
+static void transformJsonPassingArgs(ParseState *pstate, const char *constructName,
+ JsonFormatType format, List *args,
+ List **passing_values, List **passing_names);
+static void coerceJsonExprOutput(ParseState *pstate, JsonExpr *jsexpr);
+static JsonBehavior *transformJsonBehavior(ParseState *pstate, JsonBehavior *behavior,
+ JsonBehaviorType default_behavior,
+ JsonReturning *returning);
+static Node *GetJsonBehaviorConst(JsonBehaviorType btype, int location);
static Node *make_row_comparison_op(ParseState *pstate, List *opname,
List *largs, List *rargs, int location);
static Node *make_row_distinct_op(ParseState *pstate, List *opname,
@@ -359,6 +369,10 @@ transformExprRecurse(ParseState *pstate, Node *expr)
result = transformJsonSerializeExpr(pstate, (JsonSerializeExpr *) expr);
break;
+ case T_JsonFuncExpr:
+ result = transformJsonFuncExpr(pstate, (JsonFuncExpr *) expr);
+ break;
+
default:
/* should not reach here */
elog(ERROR, "unrecognized node type: %d", (int) nodeTag(expr));
@@ -3263,7 +3277,7 @@ makeJsonByteaToTextConversion(Node *expr, JsonFormat *format, int location)
static Node *
transformJsonValueExpr(ParseState *pstate, const char *constructName,
JsonValueExpr *ve, JsonFormatType default_format,
- Oid targettype)
+ Oid targettype, bool isarg)
{
Node *expr = transformExprRecurse(pstate, (Node *) ve->raw_expr);
Node *rawexpr;
@@ -3295,6 +3309,41 @@ transformJsonValueExpr(ParseState *pstate, const char *constructName,
else
format = ve->format->format_type;
}
+ else if (isarg)
+ {
+ /*
+ * Special treatment for PASSING arguments.
+ *
+ * Pass types supported by GetJsonPathVar() / JsonItemFromDatum()
+ * directly without converting to json[b].
+ */
+ switch (exprtype)
+ {
+ case BOOLOID:
+ case NUMERICOID:
+ case INT2OID:
+ case INT4OID:
+ case INT8OID:
+ case FLOAT4OID:
+ case FLOAT8OID:
+ case TEXTOID:
+ case VARCHAROID:
+ case DATEOID:
+ case TIMEOID:
+ case TIMETZOID:
+ case TIMESTAMPOID:
+ case TIMESTAMPTZOID:
+ return expr;
+
+ default:
+ if (typcategory == TYPCATEGORY_STRING)
+ return expr;
+ /* else convert argument to json[b] type */
+ break;
+ }
+
+ format = default_format;
+ }
else if (exprtype == JSONOID || exprtype == JSONBOID)
format = JS_FORMAT_DEFAULT; /* do not format json[b] types */
else
@@ -3306,7 +3355,12 @@ transformJsonValueExpr(ParseState *pstate, const char *constructName,
Node *coerced;
bool only_allow_cast = OidIsValid(targettype);
- if (!only_allow_cast &&
+ /*
+ * PASSING args are handled appropriately by GetJsonPathVar() /
+ * JsonItemFromDatum().
+ */
+ if (!isarg &&
+ !only_allow_cast &&
exprtype != BYTEAOID && typcategory != TYPCATEGORY_STRING)
ereport(ERROR,
errcode(ERRCODE_DATATYPE_MISMATCH),
@@ -3459,6 +3513,11 @@ transformJsonOutput(ParseState *pstate, const JsonOutput *output,
errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("returning SETOF types is not supported in SQL/JSON functions"));
+ if (get_typtype(ret->typid) == TYPTYPE_PSEUDO)
+ ereport(ERROR,
+ errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("returning pseudo-types is not supported in SQL/JSON functions"));
+
if (ret->format->format_type == JS_FORMAT_DEFAULT)
/* assign JSONB format when returning jsonb, or JSON format otherwise */
ret->format->format_type =
@@ -3555,7 +3614,6 @@ coerceJsonFuncExpr(ParseState *pstate, Node *expr,
/* try to coerce expression to the output type */
res = coerce_to_target_type(pstate, expr, exprtype,
returning->typid, returning->typmod,
- /* XXX throwing errors when casting to char(N) */
COERCION_EXPLICIT,
COERCE_EXPLICIT_CAST,
location);
@@ -3655,7 +3713,7 @@ transformJsonObjectConstructor(ParseState *pstate, JsonObjectConstructor *ctor)
Node *val = transformJsonValueExpr(pstate, "JSON_OBJECT()",
kv->value,
JS_FORMAT_DEFAULT,
- InvalidOid);
+ InvalidOid, false);
args = lappend(args, key);
args = lappend(args, val);
@@ -3842,7 +3900,7 @@ transformJsonObjectAgg(ParseState *pstate, JsonObjectAgg *agg)
val = transformJsonValueExpr(pstate, "JSON_OBJECTAGG()",
agg->arg->value,
JS_FORMAT_DEFAULT,
- InvalidOid);
+ InvalidOid, false);
args = list_make2(key, val);
returning = transformJsonConstructorOutput(pstate, agg->constructor->output,
@@ -3898,9 +3956,8 @@ transformJsonArrayAgg(ParseState *pstate, JsonArrayAgg *agg)
Oid aggfnoid;
Oid aggtype;
- arg = transformJsonValueExpr(pstate, "JSON_ARRAYAGG()",
- agg->arg,
- JS_FORMAT_DEFAULT, InvalidOid);
+ arg = transformJsonValueExpr(pstate, "JSON_ARRAYAGG()", agg->arg,
+ JS_FORMAT_DEFAULT, InvalidOid, false);
returning = transformJsonConstructorOutput(pstate, agg->constructor->output,
list_make1(arg));
@@ -3947,9 +4004,8 @@ transformJsonArrayConstructor(ParseState *pstate, JsonArrayConstructor *ctor)
{
JsonValueExpr *jsval = castNode(JsonValueExpr, lfirst(lc));
Node *val = transformJsonValueExpr(pstate, "JSON_ARRAY()",
- jsval,
- JS_FORMAT_DEFAULT,
- InvalidOid);
+ jsval, JS_FORMAT_DEFAULT,
+ InvalidOid, false);
args = lappend(args, val);
}
@@ -4108,7 +4164,7 @@ transformJsonParseExpr(ParseState *pstate, JsonParseExpr *jsexpr)
* function-like CASTs.
*/
arg = transformJsonValueExpr(pstate, "JSON()", jsexpr->expr,
- JS_FORMAT_JSON, returning->typid);
+ JS_FORMAT_JSON, returning->typid, false);
}
return makeJsonConstructorExpr(pstate, JSCTOR_JSON_PARSE, list_make1(arg), NULL,
@@ -4153,7 +4209,7 @@ transformJsonSerializeExpr(ParseState *pstate, JsonSerializeExpr *expr)
Node *arg = transformJsonValueExpr(pstate, "JSON_SERIALIZE()",
expr->expr,
JS_FORMAT_JSON,
- InvalidOid);
+ InvalidOid, false);
if (expr->output)
{
@@ -4187,3 +4243,474 @@ transformJsonSerializeExpr(ParseState *pstate, JsonSerializeExpr *expr)
return makeJsonConstructorExpr(pstate, JSCTOR_JSON_SERIALIZE, list_make1(arg),
NULL, returning, false, false, expr->location);
}
+
+/*
+ * Transform JSON_VALUE, JSON_QUERY, JSON_EXISTS functions into a JsonExpr node.
+ */
+static Node *
+transformJsonFuncExpr(ParseState *pstate, JsonFuncExpr *func)
+{
+ JsonExpr *jsexpr;
+ Node *path_spec;
+ const char *func_name = NULL;
+ JsonFormatType default_format;
+
+ switch (func->op)
+ {
+ case JSON_EXISTS_OP:
+ func_name = "JSON_EXISTS";
+ default_format = JS_FORMAT_DEFAULT;
+ break;
+ case JSON_QUERY_OP:
+ func_name = "JSON_QUERY";
+ default_format = JS_FORMAT_JSONB;
+ break;
+ case JSON_VALUE_OP:
+ func_name = "JSON_VALUE";
+ default_format = JS_FORMAT_DEFAULT;
+ break;
+ default:
+ elog(ERROR, "invalid JsonFuncExpr op %d", (int) func->op);
+ break;
+ }
+
+ /*
+ * Even though the syntax allows it, FORMAT JSON specification in
+ * RETURNING is meaningless except for JSON_QUERY(). Flag if not
+ * JSON_QUERY().
+ */
+ if (func->output && func->op != JSON_QUERY_OP)
+ {
+ JsonFormat *format = func->output->returning->format;
+
+ if (format->format_type != JS_FORMAT_DEFAULT ||
+ format->encoding != JS_ENC_DEFAULT)
+ ereport(ERROR,
+ errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("cannot specify FORMAT JSON in RETURNING clause of %s()",
+ func_name),
+ parser_errposition(pstate, format->location));
+ }
+
+ /* OMIT QUOTES is meaningless when strings are wrapped. */
+ if (func->op == JSON_QUERY_OP &&
+ func->quotes != JS_QUOTES_UNSPEC &&
+ (func->wrapper == JSW_CONDITIONAL ||
+ func->wrapper == JSW_UNCONDITIONAL))
+ ereport(ERROR,
+ errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("SQL/JSON QUOTES behavior must not be specified when WITH WRAPPER is used"),
+ parser_errposition(pstate, func->location));
+
+ jsexpr = makeNode(JsonExpr);
+ jsexpr->location = func->location;
+ jsexpr->op = func->op;
+
+ /*
+ * jsonpath machinery can only handle jsonb documents, so coerce the input
+ * if not already of jsonb type.
+ */
+ jsexpr->formatted_expr = transformJsonValueExpr(pstate, func_name,
+ func->context_item,
+ default_format,
+ JSONBOID,
+ false);
+ jsexpr->format = func->context_item->format;
+
+ path_spec = transformExprRecurse(pstate, func->pathspec);
+ path_spec = coerce_to_target_type(pstate, path_spec, exprType(path_spec),
+ JSONPATHOID, -1,
+ COERCION_EXPLICIT, COERCE_IMPLICIT_CAST,
+ exprLocation(path_spec));
+ if (path_spec == NULL)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("JSON path expression must be of type %s, not of type %s",
+ "jsonpath", format_type_be(exprType(path_spec))),
+ parser_errposition(pstate, exprLocation(path_spec))));
+ jsexpr->path_spec = path_spec;
+
+ /* Transform and coerce the PASSING arguments to to jsonb. */
+ transformJsonPassingArgs(pstate, func_name,
+ JS_FORMAT_JSONB,
+ func->passing,
+ &jsexpr->passing_values,
+ &jsexpr->passing_names);
+
+ /* Transform the JsonOutput into JsonReturning. */
+ jsexpr->returning = transformJsonOutput(pstate, func->output, false);
+
+ switch (func->op)
+ {
+ case JSON_EXISTS_OP:
+ /* JSON_EXISTS returns boolean by default. */
+ if (!OidIsValid(jsexpr->returning->typid))
+ {
+ jsexpr->returning->typid = BOOLOID;
+ jsexpr->returning->typmod = -1;
+ }
+
+ jsexpr->on_error = transformJsonBehavior(pstate, func->on_error,
+ JSON_BEHAVIOR_FALSE,
+ jsexpr->returning);
+ break;
+
+ case JSON_QUERY_OP:
+ /* JSON_QUERY returns jsonb by default. */
+ if (!OidIsValid(jsexpr->returning->typid))
+ {
+ JsonReturning *ret = jsexpr->returning;
+
+ ret->typid = JSONBOID;
+ ret->typmod = -1;
+ }
+
+ /*
+ * Keep quotes on scalar strings by default, omitting them only if
+ * OMIT QUOTES is specified.
+ */
+ jsexpr->omit_quotes = (func->quotes == JS_QUOTES_OMIT);
+ jsexpr->wrapper = func->wrapper;
+
+ coerceJsonExprOutput(pstate, jsexpr);
+
+ if (func->on_empty)
+ jsexpr->on_empty = transformJsonBehavior(pstate,
+ func->on_empty,
+ JSON_BEHAVIOR_NULL,
+ jsexpr->returning);
+ jsexpr->on_error = transformJsonBehavior(pstate, func->on_error,
+ JSON_BEHAVIOR_NULL,
+ jsexpr->returning);
+ break;
+
+ case JSON_VALUE_OP:
+ /* JSON_VALUE returns text by default. */
+ if (!OidIsValid(jsexpr->returning->typid))
+ {
+ jsexpr->returning->typid = TEXTOID;
+ jsexpr->returning->typmod = -1;
+ }
+
+ /*
+ * Override whatever transformJsonOutput() set these to, which
+ * assumes that output type to be jsonb.
+ */
+ jsexpr->returning->format->format_type = JS_FORMAT_DEFAULT;
+ jsexpr->returning->format->encoding = JS_ENC_DEFAULT;
+
+ /* Always omit quotes from scalar strings. */
+ jsexpr->omit_quotes = true;
+
+ coerceJsonExprOutput(pstate, jsexpr);
+
+ if (func->on_empty)
+ jsexpr->on_empty = transformJsonBehavior(pstate,
+ func->on_empty,
+ JSON_BEHAVIOR_NULL,
+ jsexpr->returning);
+ jsexpr->on_error = transformJsonBehavior(pstate, func->on_error,
+ JSON_BEHAVIOR_NULL,
+ jsexpr->returning);
+ break;
+
+ default:
+ elog(ERROR, "invalid JsonFuncExpr op %d", (int) func->op);
+ break;
+ }
+
+ return (Node *) jsexpr;
+}
+
+/*
+ * Transform a SQL/JSON PASSING clause.
+ */
+static void
+transformJsonPassingArgs(ParseState *pstate, const char *constructName,
+ JsonFormatType format, List *args,
+ List **passing_values, List **passing_names)
+{
+ ListCell *lc;
+
+ *passing_values = NIL;
+ *passing_names = NIL;
+
+ foreach(lc, args)
+ {
+ JsonArgument *arg = castNode(JsonArgument, lfirst(lc));
+ Node *expr = transformJsonValueExpr(pstate, constructName,
+ arg->val, format,
+ InvalidOid, true);
+
+ *passing_values = lappend(*passing_values, expr);
+ *passing_names = lappend(*passing_names, makeString(arg->name));
+ }
+}
+
+/*
+ * Set up to coerce the result value of JSON_VALUE() / JSON_QUERY() to the
+ * RETURNING type (default or user-specified), if needed.
+ */
+static void
+coerceJsonExprOutput(ParseState *pstate, JsonExpr *jsexpr)
+{
+ JsonReturning *returning = jsexpr->returning;
+ Node *context_item = jsexpr->formatted_expr;
+ int default_typmod;
+ Oid default_typid;
+ bool omit_quotes =
+ jsexpr->op == JSON_QUERY_OP && jsexpr->omit_quotes;
+ Node *coercion_expr = NULL;
+
+ Assert(returning);
+
+ /*
+ * Check for cases where the coercion should be handled at runtime, that
+ * is, without using a cast expression.
+ */
+ if (jsexpr->op == JSON_VALUE_OP)
+ {
+ /*
+ * Use cast expressions for types with typmod and domain types.
+ */
+ if (returning->typmod == -1 &&
+ get_typtype(returning->typid) != TYPTYPE_DOMAIN)
+ {
+ jsexpr->use_io_coercion = true;
+ return;
+ }
+ }
+ else if (jsexpr->op == JSON_QUERY_OP)
+ {
+ /*
+ * Cast functions from jsonb to the following types (jsonb_bool() et
+ * al) don't handle errors softly, so coerce either by calling
+ * json_populate_type() or the type's input function so that any
+ * errors are handled appropriately. The latter only if OMIT QUOTES is
+ * true.
+ */
+ switch (returning->typid)
+ {
+ case BOOLOID:
+ case NUMERICOID:
+ case INT2OID:
+ case INT4OID:
+ case INT8OID:
+ case FLOAT4OID:
+ case FLOAT8OID:
+ if (jsexpr->omit_quotes)
+ jsexpr->use_io_coercion = true;
+ else
+ jsexpr->use_json_coercion = true;
+ return;
+ default:
+ break;
+ }
+ }
+
+ /* Look up a cast expression. */
+
+ /*
+ * For JSON_VALUE() and for JSON_QUERY() when OMIT QUOTES is true,
+ * ExecEvalJsonExprPath() will convert a quote-stripped source value to
+ * its text representation, so use TEXTOID as the source type.
+ */
+ if (omit_quotes || jsexpr->op == JSON_VALUE_OP)
+ {
+ default_typid = TEXTOID;
+ default_typmod = -1;
+ }
+ else
+ {
+ default_typid = exprType(context_item);
+ default_typmod = exprTypmod(context_item);
+ }
+
+ if (returning->typid != default_typid ||
+ returning->typmod != default_typmod)
+ {
+ /*
+ * We abuse CaseTestExpr here as placeholder to pass the result of
+ * jsonpath evaluation as input to the coercion expression.
+ */
+ CaseTestExpr *placeholder = makeNode(CaseTestExpr);
+
+ placeholder->typeId = default_typid;
+ placeholder->typeMod = default_typmod;
+
+ coercion_expr = coerceJsonFuncExpr(pstate, (Node *) placeholder,
+ returning, false);
+ if (coercion_expr == (Node *) placeholder)
+ coercion_expr = NULL;
+ }
+
+ jsexpr->coercion_expr = coercion_expr;
+
+ if (coercion_expr == NULL)
+ {
+ /*
+ * Either no cast was found or coercion is unnecessary but still must
+ * convert the string value to the output type.
+ */
+ if (omit_quotes || jsexpr->op == JSON_VALUE_OP)
+ jsexpr->use_io_coercion = true;
+ else
+ jsexpr->use_json_coercion = true;
+ }
+
+ Assert(jsexpr->coercion_expr != NULL ||
+ (jsexpr->use_io_coercion != jsexpr->use_json_coercion));
+}
+
+/*
+ * Transform a JSON BEHAVIOR clause.
+ */
+static JsonBehavior *
+transformJsonBehavior(ParseState *pstate, JsonBehavior *behavior,
+ JsonBehaviorType default_behavior,
+ JsonReturning *returning)
+{
+ JsonBehaviorType btype = default_behavior;
+ Node *expr = NULL;
+ bool coerce_at_runtime = false;
+ int location = -1;
+
+ if (behavior)
+ {
+ btype = behavior->btype;
+ location = behavior->location;
+ if (btype == JSON_BEHAVIOR_DEFAULT)
+ {
+ expr = transformExprRecurse(pstate, behavior->expr);
+ if (!IsA(expr, Const) && !IsA(expr, FuncExpr) &&
+ !IsA(expr, OpExpr))
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("can only specify constant, non-aggregate"
+ " function, or operator expression for"
+ " DEFAULT"),
+ parser_errposition(pstate, exprLocation(expr))));
+ if (contain_var_clause(expr))
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("DEFAULT expression must not contain column references"),
+ parser_errposition(pstate, exprLocation(expr))));
+ if (expression_returns_set(expr))
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("DEFAULT expression must not return a set"),
+ parser_errposition(pstate, exprLocation(expr))));
+ }
+ }
+
+ if (expr == NULL && btype != JSON_BEHAVIOR_ERROR)
+ expr = GetJsonBehaviorConst(btype, location);
+
+ if (expr)
+ {
+ Node *coerced_expr = expr;
+ bool isnull = (IsA(expr, Const) && ((Const *) expr)->constisnull);
+
+ /*
+ * Coerce NULLs and "internal" (that is, not specified by the user)
+ * jsonb-valued expressions at runtime using json_populate_type().
+ *
+ * For other (user-specified) non-NULL values, try to find a cast and
+ * error out if one is not found.
+ */
+ if (isnull ||
+ (exprType(expr) == JSONBOID &&
+ btype == default_behavior))
+ coerce_at_runtime = true;
+ else
+ coerced_expr =
+ coerce_to_target_type(pstate, expr, exprType(expr),
+ returning->typid, returning->typmod,
+ COERCION_EXPLICIT, COERCE_EXPLICIT_CAST,
+ exprLocation((Node *) behavior));
+
+ if (coerced_expr == NULL)
+ ereport(ERROR,
+ errcode(ERRCODE_CANNOT_COERCE),
+ errmsg("cannot cast behavior expression of type %s to %s",
+ format_type_be(exprType(expr)),
+ format_type_be(returning->typid)),
+ parser_errposition(pstate, exprLocation(expr)));
+ else
+ expr = coerced_expr;
+ }
+
+ if (behavior)
+ behavior->expr = expr;
+ else
+ behavior = makeJsonBehavior(btype, expr, location);
+
+ behavior->coerce = coerce_at_runtime;
+
+ return behavior;
+}
+
+/*
+ * Returns a Const node holding the value for the given non-ERROR
+ * JsonBehaviorType.
+ */
+static Node *
+GetJsonBehaviorConst(JsonBehaviorType btype, int location)
+{
+ Datum val = (Datum) 0;
+ Oid typid = JSONBOID;
+ int len = -1;
+ bool isbyval = false;
+ bool isnull = false;
+ Const *con;
+
+ switch (btype)
+ {
+ case JSON_BEHAVIOR_EMPTY_ARRAY:
+ val = DirectFunctionCall1(jsonb_in, CStringGetDatum("[]"));
+ break;
+
+ case JSON_BEHAVIOR_EMPTY_OBJECT:
+ val = DirectFunctionCall1(jsonb_in, CStringGetDatum("{}"));
+ break;
+
+ case JSON_BEHAVIOR_TRUE:
+ val = BoolGetDatum(true);
+ typid = BOOLOID;
+ len = sizeof(bool);
+ isbyval = true;
+ break;
+
+ case JSON_BEHAVIOR_FALSE:
+ val = BoolGetDatum(false);
+ typid = BOOLOID;
+ len = sizeof(bool);
+ isbyval = true;
+ break;
+
+ case JSON_BEHAVIOR_NULL:
+ case JSON_BEHAVIOR_UNKNOWN:
+ case JSON_BEHAVIOR_EMPTY:
+ val = (Datum) 0;
+ isnull = true;
+ typid = INT4OID;
+ len = sizeof(int32);
+ isbyval = true;
+ break;
+
+ /* These two behavior types are handled by the caller. */
+ case JSON_BEHAVIOR_DEFAULT:
+ case JSON_BEHAVIOR_ERROR:
+ Assert(false);
+ break;
+
+ default:
+ elog(ERROR, "unrecognized SQL/JSON behavior %d", btype);
+ break;
+ }
+
+ con = makeConst(typid, -1, InvalidOid, len, val, isnull, isbyval);
+ con->location = location;
+
+ return (Node *) con;
+}