expand POST /products to allow specifying categories the product is in

11 files changed, 549 insertions, 196 deletions

diff --git a/src/backend/taler-merchant-httpd_private-post-products.c b/src/backend/taler-merchant-httpd_private-post-products.c
index 3cad91a9..3edc0c16 100644
--- a/src/backend/taler-merchant-httpd_private-post-products.c
+++ b/src/backend/taler-merchant-httpd_private-post-products.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  (C) 2020 Taler Systems SA
+  (C) 2020-2024 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Affero General Public License as
@@ -28,50 +28,6 @@
 #include <taler/taler_json_lib.h>
 
 
-/**
- * How often do we retry the simple INSERT database transaction?
- */
-#define MAX_RETRIES 3
-
-
-/**
- * Check if the two products are identical.
- *
- * @param p1 product to compare
- * @param p2 other product to compare
- * @return true if they are 'equal', false if not or of payto_uris is not an array
- */
-static bool
-products_equal (const struct TALER_MERCHANTDB_ProductDetails *p1,
-                const struct TALER_MERCHANTDB_ProductDetails *p2)
-{
-  return ( (0 == strcmp (p1->description,
-                         p2->description)) &&
-           (1 == json_equal (p1->description_i18n,
-                             p2->description_i18n)) &&
-           (0 == strcmp (p1->unit,
-                         p2->unit)) &&
-           (GNUNET_OK ==
-            TALER_amount_cmp_currency (&p1->price,
-                                       &p2->price)) &&
-           (0 == TALER_amount_cmp (&p1->price,
-                                   &p2->price)) &&
-           (1 == json_equal (p1->taxes,
-                             p2->taxes)) &&
-           (p1->total_stock == p2->total_stock) &&
-           (p1->total_sold == p2->total_sold) &&
-           (p1->total_lost == p2->total_lost) &&
-           (p1->minimum_age == p2->minimum_age) &&
-           (0 == strcmp (p1->image,
-                         p2->image)) &&
-           (1 == json_equal (p1->address,
-                             p2->address)) &&
-           (GNUNET_TIME_timestamp_cmp (p1->next_restock,
-                                       ==,
-                                       p2->next_restock) ) );
-}
-
-
 MHD_RESULT
 TMH_private_post_products (const struct TMH_RequestHandler *rh,
                            struct MHD_Connection *connection,
@@ -79,9 +35,9 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
 {
   struct TMH_MerchantInstance *mi = hc->instance;
   struct TALER_MERCHANTDB_ProductDetails pd = { 0 };
+  const json_t *categories = NULL;
   const char *product_id;
   int64_t total_stock;
-  enum GNUNET_DB_QueryStatus qs;
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_string ("product_id",
                              &product_id),
@@ -103,6 +59,10 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
       GNUNET_JSON_spec_json ("taxes",
                              &pd.taxes),
       NULL),
+    GNUNET_JSON_spec_mark_optional (
+      GNUNET_JSON_spec_array_const ("categories",
+                                    &categories),
+      NULL),
     GNUNET_JSON_spec_int64 ("total_stock",
                             &total_stock),
     GNUNET_JSON_spec_mark_optional (
@@ -119,6 +79,13 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
       NULL),
     GNUNET_JSON_spec_end ()
   };
+  size_t num_cats = 0;
+  uint64_t *cats = NULL;
+  bool conflict;
+  bool no_instance;
+  ssize_t no_cat;
+  enum GNUNET_DB_QueryStatus qs;
+  MHD_RESULT ret;
 
   GNUNET_assert (NULL != mi);
   {
@@ -138,13 +105,33 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
   if (total_stock < -1)
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "total_stock");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "total_stock");
+    goto cleanup;
   }
+  num_cats = json_array_size (categories);
+  cats = GNUNET_new_array (num_cats,
+                           uint64_t);
+  {
+    size_t idx;
+    json_t *val;
 
+    json_array_foreach (categories, idx, val)
+    {
+      if (! json_is_integer (val))
+      {
+        GNUNET_break_op (0);
+        ret = TALER_MHD_reply_with_error (connection,
+                                          MHD_HTTP_BAD_REQUEST,
+                                          TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                          "categories");
+        goto cleanup;
+      }
+      cats[idx] = json_integer_value (val);
+    }
+  }
 
   if (-1 == total_stock)
     pd.total_stock = INT64_MAX;
@@ -162,31 +149,31 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
   if (! TMH_taxes_array_valid (pd.taxes))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "taxes");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "taxes");
+    goto cleanup;
   }
 
   if (! TMH_location_object_valid (pd.address))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "address");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "address");
+    goto cleanup;
   }
 
   if (! TALER_JSON_check_i18n (pd.description_i18n))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "description_i18n");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "description_i18n");
+    goto cleanup;
   }
 
   if (NULL == pd.image)
@@ -194,110 +181,88 @@ TMH_private_post_products (const struct TMH_RequestHandler *rh,
   if (! TMH_image_data_url_valid (pd.image))
   {
     GNUNET_break_op (0);
-    GNUNET_JSON_parse_free (spec);
-    return TALER_MHD_reply_with_error (connection,
-                                       MHD_HTTP_BAD_REQUEST,
-                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
-                                       "image");
+    ret = TALER_MHD_reply_with_error (connection,
+                                      MHD_HTTP_BAD_REQUEST,
+                                      TALER_EC_GENERIC_PARAMETER_MALFORMED,
+                                      "image");
+    goto cleanup;
   }
 
-  /* finally, interact with DB until no serialization error */
-  for (unsigned int i = 0; i<MAX_RETRIES; i++)
+  qs = TMH_db->insert_product (TMH_db->cls,
+                               mi->settings.id,
+                               product_id,
+                               &pd,
+                               num_cats,
+                               cats,
+                               &no_instance,
+                               &conflict,
+                               &no_cat);
+  switch (qs)
   {
-    /* Test if an product of this id is known */
-    struct TALER_MERCHANTDB_ProductDetails epd;
-
-    if (GNUNET_OK !=
-        TMH_db->start (TMH_db->cls,
-                       "/post products"))
-    {
-      GNUNET_break (0);
-      GNUNET_JSON_parse_free (spec);
-      return TALER_MHD_reply_with_error (connection,
-                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                         TALER_EC_GENERIC_DB_START_FAILED,
-                                         NULL);
-    }
-    qs = TMH_db->lookup_product (TMH_db->cls,
-                                 mi->settings.id,
-                                 product_id,
-                                 &epd);
-    switch (qs)
-    {
-    case GNUNET_DB_STATUS_HARD_ERROR:
-      /* Clean up and fail hard */
-      GNUNET_break (0);
-      TMH_db->rollback (TMH_db->cls);
-      GNUNET_JSON_parse_free (spec);
-      return TALER_MHD_reply_with_error (connection,
-                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                         TALER_EC_GENERIC_DB_FETCH_FAILED,
-                                         NULL);
-    case GNUNET_DB_STATUS_SOFT_ERROR:
-      /* restart transaction */
-      goto retry;
-    case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
-      /* Good, we can proceed! */
-      break;
-    case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
-      /* idempotency check: is epd == pd? */
-      {
-        bool eq;
-
-        eq = products_equal (&pd,
-                             &epd);
-        TALER_MERCHANTDB_product_details_free (&epd);
-        TMH_db->rollback (TMH_db->cls);
-        GNUNET_JSON_parse_free (spec);
-        return eq
-          ? TALER_MHD_reply_static (connection,
-                                    MHD_HTTP_NO_CONTENT,
-                                    NULL,
-                                    NULL,
-                                    0)
-          : TALER_MHD_reply_with_error (connection,
-                                        MHD_HTTP_CONFLICT,
-                                        TALER_EC_MERCHANT_PRIVATE_POST_PRODUCTS_CONFLICT_PRODUCT_EXISTS,
-                                        product_id);
-      }
-    } /* end switch (qs) */
-
-    qs = TMH_db->insert_product (TMH_db->cls,
-                                 mi->settings.id,
-                                 product_id,
-                                 &pd);
-    if (GNUNET_DB_STATUS_HARD_ERROR == qs)
-    {
-      TMH_db->rollback (TMH_db->cls);
-      break;
-    }
-    if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs)
-    {
-      qs = TMH_db->commit (TMH_db->cls);
-      if (GNUNET_DB_STATUS_SOFT_ERROR != qs)
-        break;
-    }
-retry:
-    GNUNET_assert (GNUNET_DB_STATUS_SOFT_ERROR == qs);
-    TMH_db->rollback (TMH_db->cls);
-  } /* for RETRIES loop */
-  GNUNET_JSON_parse_free (spec);
-  if (qs < 0)
-  {
-    GNUNET_break (0);
-    return TALER_MHD_reply_with_error (
+  case GNUNET_DB_STATUS_HARD_ERROR:
+  case GNUNET_DB_STATUS_SOFT_ERROR:
+    ret = TALER_MHD_reply_with_error (
       connection,
       MHD_HTTP_INTERNAL_SERVER_ERROR,
       (GNUNET_DB_STATUS_SOFT_ERROR == qs)
       ? TALER_EC_GENERIC_DB_SOFT_FAILURE
       : TALER_EC_GENERIC_DB_COMMIT_FAILED,
       NULL);
+    goto cleanup;
+  case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
+    ret = TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_INTERNAL_SERVER_ERROR,
+      TALER_EC_GENERIC_DB_INVARIANT_FAILURE,
+      NULL);
+    goto cleanup;
+  case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
+    break;
   }
-  return TALER_MHD_reply_static (connection,
-                                 MHD_HTTP_NO_CONTENT,
-                                 NULL,
-                                 NULL,
-                                 0);
+  if (no_instance)
+  {
+    ret = TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_NOT_FOUND,
+      TALER_EC_MERCHANT_GENERIC_INSTANCE_UNKNOWN,
+      mi->settings.id);
+    goto cleanup;
+  }
+  if (conflict)
+  {
+    ret = TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_CONFLICT,
+      TALER_EC_MERCHANT_PRIVATE_POST_PRODUCTS_CONFLICT_PRODUCT_EXISTS,
+      product_id);
+    goto cleanup;
+  }
+  if (-1 != no_cat)
+  {
+    char nocats[24];
+
+    GNUNET_break_op (0);
+    TMH_db->rollback (TMH_db->cls);
+    GNUNET_snprintf (nocats,
+                     sizeof (nocats),
+                     "%llu",
+                     (unsigned long long) no_cat);
+    ret = TALER_MHD_reply_with_error (
+      connection,
+      MHD_HTTP_NOT_FOUND,
+      TALER_EC_MERCHANT_GENERIC_CATEGORY_UNKNOWN,
+      nocats);
+    goto cleanup;
+  }
+  ret = TALER_MHD_reply_static (connection,
+                                MHD_HTTP_NO_CONTENT,
+                                NULL,
+                                NULL,
+                                0);
+cleanup:
+  GNUNET_JSON_parse_free (spec);
+  GNUNET_free (cats);
+  return ret;
 }
 
 
diff --git a/src/backenddb/merchant-0001.sql b/src/backenddb/merchant-0001.sql
index 2adb9996..ca753a04 100644
--- a/src/backenddb/merchant-0001.sql
+++ b/src/backenddb/merchant-0001.sql
@@ -194,7 +194,7 @@ CREATE TABLE IF NOT EXISTS merchant_inventory
   ,description TEXT NOT NULL
   ,description_i18n BYTEA NOT NULL
   ,unit TEXT NOT NULL
-  ,image BYTEA NOT NULL
+  ,image BYTEA NOT NULL -- NOTE: merchant-0006 changes this to TEXT!
   ,taxes BYTEA NOT NULL
   ,price taler_amount_currency NOT NULL
   ,total_stock BIGINT NOT NULL
diff --git a/src/backenddb/merchant-0006.sql b/src/backenddb/merchant-0006.sql
index 2b24e526..00b9afff 100644
--- a/src/backenddb/merchant-0006.sql
+++ b/src/backenddb/merchant-0006.sql
@@ -22,6 +22,9 @@ SELECT _v.register_patch('merchant-0006', NULL, NULL);
 
 SET search_path TO merchant;
 
+ALTER TABLE merchant_inventory
+  ALTER COLUMN image SET DATA TYPE TEXT;
+
 CREATE TABLE IF NOT EXISTS merchant_categories
   (category_serial BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY
   ,merchant_serial BIGINT NOT NULL
diff --git a/src/backenddb/pg_insert_product.c b/src/backenddb/pg_insert_product.c
index 55db57e9..c46255c9 100644
--- a/src/backenddb/pg_insert_product.c
+++ b/src/backenddb/pg_insert_product.c
@@ -1,6 +1,6 @@
 /*
    This file is part of TALER
-   Copyright (C) 2022 Taler Systems SA
+   Copyright (C) 2022-2024 Taler Systems SA
 
    TALER is free software; you can redistribute it and/or modify it under the
    terms of the GNU General Public License as published by the Free Software
@@ -30,7 +30,12 @@ enum GNUNET_DB_QueryStatus
 TMH_PG_insert_product (void *cls,
                        const char *instance_id,
                        const char *product_id,
-                       const struct TALER_MERCHANTDB_ProductDetails *pd)
+                       const struct TALER_MERCHANTDB_ProductDetails *pd,
+                       size_t num_cats,
+                       const uint64_t *cats,
+                       bool *no_instance,
+                       bool *conflict,
+                       ssize_t *no_cat)
 {
   struct PostgresClosure *pg = cls;
   struct GNUNET_PQ_QueryParam params[] = {
@@ -42,36 +47,46 @@ TMH_PG_insert_product (void *cls,
     GNUNET_PQ_query_param_string (pd->image),
     TALER_PQ_query_param_json (pd->taxes),
     TALER_PQ_query_param_amount_with_currency (pg->conn,
-                                 &pd->price),
+                                               &pd->price),
     GNUNET_PQ_query_param_uint64 (&pd->total_stock),
     TALER_PQ_query_param_json (pd->address),
     GNUNET_PQ_query_param_timestamp (&pd->next_restock),
     GNUNET_PQ_query_param_uint32 (&pd->minimum_age),
+    GNUNET_PQ_query_param_array_uint64 (num_cats,
+                                        cats,
+                                        pg->conn),
     GNUNET_PQ_query_param_end
   };
+  uint64_t ncat;
+  bool cats_found = true;
+  struct GNUNET_PQ_ResultSpec rs[] = {
+    GNUNET_PQ_result_spec_bool ("conflict",
+                                conflict),
+    GNUNET_PQ_result_spec_bool ("no_instance",
+                                no_instance),
+    GNUNET_PQ_result_spec_allow_null (
+      GNUNET_PQ_result_spec_uint64 ("no_cat",
+                                    &ncat),
+      &cats_found),
+    GNUNET_PQ_result_spec_end
+  };
+  enum GNUNET_DB_QueryStatus qs;
 
+  *no_cat = -1;
   check_connection (pg);
   PREPARE (pg,
            "insert_product",
-           "INSERT INTO merchant_inventory"
-           "(merchant_serial"
-           ",product_id"
-           ",description"
-           ",description_i18n"
-           ",unit"
-           ",image"
-           ",taxes"
-           ",price"
-           ",total_stock"
-           ",address"
-           ",next_restock"
-           ",minimum_age"
-           ")"
-           " SELECT merchant_serial,"
-           " $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12"
-           " FROM merchant_instances"
-           " WHERE merchant_id=$1");
-  return GNUNET_PQ_eval_prepared_non_select (pg->conn,
-                                             "insert_product",
-                                             params);
+           "SELECT"
+           " out_conflict AS conflict"
+           ",out_no_cat AS no_cat"
+           ",out_no_instance AS no_instance"
+           " FROM merchant_do_insert_product"
+           "($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13);");
+  qs = GNUNET_PQ_eval_prepared_singleton_select (pg->conn,
+                                                 "insert_product",
+                                                 params,
+                                                 rs);
+  GNUNET_PQ_cleanup_query_params_closures (params);
+  *no_cat = (cats_found) ? -1 : (ssize_t) ncat;
+  return qs;
 }
diff --git a/src/backenddb/pg_insert_product.h b/src/backenddb/pg_insert_product.h
index 169bd150..5e85228e 100644
--- a/src/backenddb/pg_insert_product.h
+++ b/src/backenddb/pg_insert_product.h
@@ -32,12 +32,24 @@
  * @param instance_id instance to insert product for
  * @param product_id product identifier of product to insert
  * @param pd the product details to insert
+ * @param num_cats length of @a cats array
+ * @param cats array of categories the product is in
+ * @param[out] no_instance set to true if @a instance_id is unknown
+ * @param[out] conflict set to true if a conflicting
+ *        product already exists in the database
+ * @param[out] no_cat set to index of non-existing category from @a cats, or -1 if all @a cats were found
  * @return database result code
  */
 enum GNUNET_DB_QueryStatus
 TMH_PG_insert_product (void *cls,
                        const char *instance_id,
                        const char *product_id,
-                       const struct TALER_MERCHANTDB_ProductDetails *pd);
+                       const struct TALER_MERCHANTDB_ProductDetails *pd,
+                       size_t num_cats,
+                       const uint64_t *cats,
+                       bool *no_instance,
+                       bool *conflict,
+                       ssize_t *no_cat);
+
 
 #endif
diff --git a/src/backenddb/pg_insert_product.sql b/src/backenddb/pg_insert_product.sql
new file mode 100644
index 00000000..4abf4469
--- /dev/null
+++ b/src/backenddb/pg_insert_product.sql
@@ -0,0 +1,175 @@
+--
+-- This file is part of TALER
+-- Copyright (C) 2024 Taler Systems SA
+--
+-- TALER is free software; you can redistribute it and/or modify it under the
+-- terms of the GNU General Public License as published by the Free Software
+-- Foundation; either version 3, or (at your option) any later version.
+--
+-- TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+-- WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+-- A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License along with
+-- TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+--
+
+
+CREATE OR REPLACE FUNCTION merchant_do_insert_product (
+  IN in_instance_id TEXT,
+  IN in_product_id TEXT,
+  IN in_description TEXT,
+  IN in_description_i18n BYTEA,
+  IN in_unit TEXT,
+  IN in_image TEXT,
+  IN in_taxes BYTEA,
+  IN in_price taler_amount_currency,
+  IN in_total_stock INT8,
+  IN in_address BYTEA,
+  IN in_next_restock INT8,
+  IN in_minimum_age INT4,
+  IN ina_categories INT8[],
+  OUT out_no_instance BOOL,
+  OUT out_conflict BOOL,
+  OUT out_no_cat INT8)
+LANGUAGE plpgsql
+AS $$
+DECLARE
+  my_merchant_id INT8;
+  my_product_serial INT8;
+  i INT8;
+  ini_cat INT8;
+BEGIN
+
+-- Which instance are we using?
+SELECT merchant_serial
+  INTO my_merchant_id
+  FROM merchant_instances
+ WHERE merchant_id=in_instance_id;
+
+IF NOT FOUND
+THEN
+  out_no_instance=TRUE;
+  out_conflict=FALSE;
+  out_no_cat=NULL;
+  RETURN;
+END IF;
+out_no_instance=FALSE;
+
+INSERT INTO merchant_inventory
+ (merchant_serial
+ ,product_id
+ ,description
+ ,description_i18n
+ ,unit
+ ,image
+ ,taxes
+ ,price
+ ,total_stock
+ ,address
+ ,next_restock
+ ,minimum_age
+) VALUES (
+  my_merchant_id
+ ,in_product_id
+ ,in_description
+ ,in_description_i18n
+ ,in_unit
+ ,in_image
+ ,in_taxes
+ ,in_price
+ ,in_total_stock
+ ,in_address
+ ,in_next_restock
+ ,in_minimum_age)
+ON CONFLICT (merchant_serial, product_id) DO NOTHING
+ RETURNING product_serial
+ INTO my_product_serial;
+
+
+IF NOT FOUND
+THEN
+  -- Check for idempotency
+  SELECT product_serial
+    INTO my_product_serial
+    FROM merchant_inventory
+  WHERE merchant_serial=my_merchant_id
+    AND product_id=in_product_id
+    AND description=in_description
+    AND description_i18n=in_description_i18n
+    AND unit=in_unit
+    AND image=in_image
+    AND taxes=in_taxes
+    AND price=in_price
+    AND total_stock=in_total_stock
+    AND address=in_address
+    AND next_restock=in_next_restock
+    AND minimum_age=in_minimum_age;
+  IF NOT FOUND
+  THEN
+    out_conflict=TRUE;
+    out_no_cat=NULL;
+    RETURN;
+  END IF;
+
+  -- Check categories match as well
+  FOR i IN 1..COALESCE(array_length(ina_categories,1),0)
+  LOOP
+    ini_cat=ina_categories[i];
+
+    PERFORM
+      FROM merchant_product_categories
+      WHERE product_serial=my_product_serial
+        AND category_serial=ini_cat;
+    IF NOT FOUND
+    THEN
+      out_conflict=TRUE;
+      out_no_cat=NULL;
+      RETURN;
+    END IF;
+  END LOOP;
+
+  -- Also check there are no additional categories
+  -- in either set.
+  SELECT COUNT(*)
+    INTO i
+    FROM merchant_product_categories
+    WHERE product_serial=my_product_serial;
+  IF i != array_length(ina_categories,1)
+  THEN
+    out_conflict=TRUE;
+    out_no_cat=NULL;
+    RETURN;
+  END IF;
+
+  -- Is idempotent!
+  out_conflict=FALSE;
+  out_no_cat=NULL;
+  RETURN;
+END IF;
+out_conflict=FALSE;
+
+
+-- Add categories
+FOR i IN 1..COALESCE(array_length(ina_categories,1),0)
+LOOP
+  ini_cat=ina_categories[i];
+
+  INSERT INTO merchant_product_categories
+   (product_serial
+   ,category_serial)
+  VALUES
+   (my_product_serial
+   ,ini_cat)
+  ON CONFLICT DO NOTHING;
+
+  IF NOT FOUND
+  THEN
+    out_no_cat=i;
+    RETURN;
+  END IF;
+END LOOP;
+
+-- Success!
+out_no_cat=NULL;
+END $$;
diff --git a/src/backenddb/procedures.sql.in b/src/backenddb/procedures.sql.in
index 3ebf8b8b..3588c2e9 100644
--- a/src/backenddb/procedures.sql.in
+++ b/src/backenddb/procedures.sql.in
@@ -19,6 +19,7 @@ BEGIN;
 SET search_path TO merchant;
 
 #include "pg_insert_deposit_to_transfer.sql"
+#include "pg_insert_product.sql"
 #include "pg_insert_transfer_details.sql"
 
 COMMIT;
diff --git a/src/backenddb/test_merchantdb.c b/src/backenddb/test_merchantdb.c
index fbb662f8..de8b2b9a 100644
--- a/src/backenddb/test_merchantdb.c
+++ b/src/backenddb/test_merchantdb.c
@@ -797,20 +797,48 @@ check_products_equal (const struct TALER_MERCHANTDB_ProductDetails *a,
  *
  * @param instance the instance to insert the product for.
  * @param product the product data to insert.
+ * @param num_cats length of the @a cats array
+ * @param cats array of categories for the product
  * @param expected_result the result we expect the db to return.
+ * @param expect_conflict expected conflict status
+ * @param expect_no_instance expected instance missing status
+ * @param expected_no_cat expected category missing index
  * @return 0 when successful, 1 otherwise.
  */
 static int
 test_insert_product (const struct InstanceData *instance,
                      const struct ProductData *product,
-                     enum GNUNET_DB_QueryStatus expected_result)
+                     unsigned int num_cats,
+                     const uint64_t *cats,
+                     enum GNUNET_DB_QueryStatus expected_result,
+                     bool expect_conflict,
+                     bool expect_no_instance,
+                     ssize_t expected_no_cat)
 {
+  bool conflict;
+  bool no_instance;
+  ssize_t no_cat;
+
   TEST_COND_RET_ON_FAIL (expected_result ==
                          plugin->insert_product (plugin->cls,
                                                  instance->instance.id,
                                                  product->id,
-                                                 &product->product),
+                                                 &product->product,
+                                                 num_cats,
+                                                 cats,
+                                                 &no_instance,
+                                                 &conflict,
+                                                 &no_cat),
                          "Insert product failed\n");
+  if (expected_result > 0)
+  {
+    TEST_COND_RET_ON_FAIL (no_instance == expect_no_instance,
+                           "Conflict returned");
+    TEST_COND_RET_ON_FAIL (conflict == expect_conflict,
+                           "Conflict returned");
+    TEST_COND_RET_ON_FAIL (no_cat == expected_no_cat,
+                           "Wrong category missing returned");
+  }
   return 0;
 }
 
@@ -1076,18 +1104,46 @@ run_test_products (struct TestProducts_Closure *cls)
   /* Test that insert without an instance fails */
   TEST_RET_ON_FAIL (test_insert_product (&cls->instance,
                                          &cls->products[0],
-                                         GNUNET_DB_STATUS_SUCCESS_NO_RESULTS));
+                                         0,
+                                         NULL,
+                                         GNUNET_DB_STATUS_SUCCESS_ONE_RESULT,
+                                         false,
+                                         true,
+                                         -1));
   /* Insert the instance */
   TEST_RET_ON_FAIL (test_insert_instance (&cls->instance,
                                           GNUNET_DB_STATUS_SUCCESS_ONE_RESULT));
   /* Test inserting a product */
   TEST_RET_ON_FAIL (test_insert_product (&cls->instance,
                                          &cls->products[0],
-                                         GNUNET_DB_STATUS_SUCCESS_ONE_RESULT));
-  /* Test that double insert fails */
+                                         0,
+                                         NULL,
+                                         GNUNET_DB_STATUS_SUCCESS_ONE_RESULT,
+                                         false,
+                                         false,
+                                         -1));
+  /* Test that double insert succeeds */
   TEST_RET_ON_FAIL (test_insert_product (&cls->instance,
                                          &cls->products[0],
-                                         GNUNET_DB_STATUS_SUCCESS_NO_RESULTS));
+                                         0,
+                                         NULL,
+                                         GNUNET_DB_STATUS_SUCCESS_ONE_RESULT,
+                                         false,
+                                         false,
+                                         -1));
+  /* Test that conflicting insert fails */
+  {
+    uint64_t cat = 42;
+
+    TEST_RET_ON_FAIL (test_insert_product (&cls->instance,
+                                           &cls->products[0],
+                                           1,
+                                           &cat,
+                                           GNUNET_DB_STATUS_SUCCESS_ONE_RESULT,
+                                           true,
+                                           false,
+                                           -1));
+  }
   /* Test lookup of individual products */
   TEST_RET_ON_FAIL (test_lookup_product (&cls->instance,
                                          &cls->products[0]));
@@ -1156,7 +1212,12 @@ run_test_products (struct TestProducts_Closure *cls)
   /* Test collective product lookup */
   TEST_RET_ON_FAIL (test_insert_product (&cls->instance,
                                          &cls->products[1],
-                                         GNUNET_DB_STATUS_SUCCESS_ONE_RESULT));
+                                         0,
+                                         NULL,
+                                         GNUNET_DB_STATUS_SUCCESS_ONE_RESULT,
+                                         false,
+                                         false,
+                                         -1));
   TEST_RET_ON_FAIL (test_lookup_products (&cls->instance,
                                           2,
                                           cls->products));
@@ -2059,7 +2120,12 @@ run_test_orders (struct TestOrders_Closure *cls)
   /* Test order lock */
   TEST_RET_ON_FAIL (test_insert_product (&cls->instance,
                                          &cls->product,
-                                         GNUNET_DB_STATUS_SUCCESS_ONE_RESULT));
+                                         0,
+                                         NULL,
+                                         GNUNET_DB_STATUS_SUCCESS_ONE_RESULT,
+                                         false,
+                                         false,
+                                         -1));
   if (1 != plugin->insert_order_lock (plugin->cls,
                                       cls->instance.instance.id,
                                       cls->orders[0].id,
diff --git a/src/include/taler_merchant_service.h b/src/include/taler_merchant_service.h
index 537a2485..68ab80fa 100644
--- a/src/include/taler_merchant_service.h
+++ b/src/include/taler_merchant_service.h
@@ -1707,6 +1707,54 @@ TALER_MERCHANT_products_post2 (
 
 
 /**
+ * Make a POST /products request to add a product to the
+ * inventory.
+ *
+ * @param ctx the context
+ * @param backend_url HTTP base URL for the backend
+ * @param product_id identifier to use for the product
+ * @param description description of the product
+ * @param description_i18n Map from IETF BCP 47 language tags to localized descriptions
+ * @param unit unit in which the product is measured (liters, kilograms, packages, etc.)
+ * @param price the price for one @a unit of the product, zero is used to imply that
+ *              this product is not sold separately or that the price is not fixed and
+ *              must be supplied by the front-end.  If non-zero, price must include
+ *              applicable taxes.
+ * @param image base64-encoded product image
+ * @param taxes list of taxes paid by the merchant
+ * @param total_stock in @a units, -1 to indicate "infinite" (i.e. electronic books)
+ * @param address where the product is in stock
+ * @param next_restock when the next restocking is expected to happen, 0 for unknown,
+ *                     #GNUNET_TIME_UNIT_FOREVER_ABS for 'never'.
+ * @param minimum_age minimum age the buyer must have
+ * @param num_cats length of the @a cats array
+ * @param cats array of categories the product is in
+ * @param cb function to call with the backend's result
+ * @param cb_cls closure for @a cb
+ * @return the request handle; NULL upon error
+ */
+struct TALER_MERCHANT_ProductsPostHandle *
+TALER_MERCHANT_products_post3 (
+  struct GNUNET_CURL_Context *ctx,
+  const char *backend_url,
+  const char *product_id,
+  const char *description,
+  const json_t *description_i18n,
+  const char *unit,
+  const struct TALER_Amount *price,
+  const char *image,
+  const json_t *taxes,
+  int64_t total_stock,
+  const json_t *address,
+  struct GNUNET_TIME_Timestamp next_restock,
+  uint32_t minimum_age,
+  unsigned int num_cats,
+  const uint64_t *cats,
+  TALER_MERCHANT_ProductsPostCallback cb,
+  void *cb_cls);
+
+
+/**
  * Cancel POST /products operation.
  *
  * @param pph operation to cancel
diff --git a/src/include/taler_merchantdb_plugin.h b/src/include/taler_merchantdb_plugin.h
index 7c009b89..12c00833 100644
--- a/src/include/taler_merchantdb_plugin.h
+++ b/src/include/taler_merchantdb_plugin.h
@@ -1758,13 +1758,24 @@ struct TALER_MERCHANTDB_Plugin
    * @param instance_id instance to insert product for
    * @param product_id product identifier of product to insert
    * @param pd the product details to insert
+   * @param num_cats length of @a cats array
+   * @param cats array of categories the product is in
+   * @param[out] no_instance set to true if @a instance_id is unknown
+   * @param[out] conflict set to true if a conflicting
+   *        product already exists in the database
+   * @param[out] no_cat set to index of non-existing category from @a cats, or -1 if all @a cats were found
    * @return database result code
    */
   enum GNUNET_DB_QueryStatus
   (*insert_product)(void *cls,
                     const char *instance_id,
                     const char *product_id,
-                    const struct TALER_MERCHANTDB_ProductDetails *pd);
+                    const struct TALER_MERCHANTDB_ProductDetails *pd,
+                    size_t num_cats,
+                    const uint64_t *cats,
+                    bool *no_instance,
+                    bool *conflict,
+                    ssize_t *no_cat);
 
   /**
    * Update details about a particular product. Note that the
diff --git a/src/lib/merchant_api_post_products.c b/src/lib/merchant_api_post_products.c
index 0f09f397..5d0ad27e 100644
--- a/src/lib/merchant_api_post_products.c
+++ b/src/lib/merchant_api_post_products.c
@@ -159,7 +159,7 @@ handle_post_products_finished (void *cls,
 
 
 struct TALER_MERCHANT_ProductsPostHandle *
-TALER_MERCHANT_products_post2 (
+TALER_MERCHANT_products_post3 (
   struct GNUNET_CURL_Context *ctx,
   const char *backend_url,
   const char *product_id,
@@ -173,12 +173,28 @@ TALER_MERCHANT_products_post2 (
   const json_t *address,
   struct GNUNET_TIME_Timestamp next_restock,
   uint32_t minimum_age,
+  unsigned int num_cats,
+  const uint64_t *cats,
   TALER_MERCHANT_ProductsPostCallback cb,
   void *cb_cls)
 {
   struct TALER_MERCHANT_ProductsPostHandle *pph;
   json_t *req_obj;
+  json_t *categories;
 
+  if (0 == num_cats)
+  {
+    categories = NULL;
+  }
+  else
+  {
+    categories = json_array ();
+    GNUNET_assert (NULL != categories);
+    for (unsigned int i = 0; i<num_cats; i++)
+      GNUNET_assert (0 ==
+                     json_array_append_new (categories,
+                                            json_integer (cats[i])));
+  }
   req_obj = GNUNET_JSON_PACK (
     GNUNET_JSON_pack_string ("product_id",
                              product_id),
@@ -187,6 +203,9 @@ TALER_MERCHANT_products_post2 (
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_object_incref ("description_i18n",
                                       (json_t *) description_i18n)),
+    GNUNET_JSON_pack_allow_null (
+      GNUNET_JSON_pack_array_steal ("categories",
+                                    categories)),
     GNUNET_JSON_pack_string ("unit",
                              unit),
     TALER_JSON_pack_amount ("price",
@@ -243,6 +262,44 @@ TALER_MERCHANT_products_post2 (
 
 
 struct TALER_MERCHANT_ProductsPostHandle *
+TALER_MERCHANT_products_post2 (
+  struct GNUNET_CURL_Context *ctx,
+  const char *backend_url,
+  const char *product_id,
+  const char *description,
+  const json_t *description_i18n,
+  const char *unit,
+  const struct TALER_Amount *price,
+  const char *image,
+  const json_t *taxes,
+  int64_t total_stock,
+  const json_t *address,
+  struct GNUNET_TIME_Timestamp next_restock,
+  uint32_t minimum_age,
+  TALER_MERCHANT_ProductsPostCallback cb,
+  void *cb_cls)
+{
+  return TALER_MERCHANT_products_post3 (ctx,
+                                        backend_url,
+                                        product_id,
+                                        description,
+                                        description_i18n,
+                                        unit,
+                                        price,
+                                        image,
+                                        taxes,
+                                        total_stock,
+                                        address,
+                                        next_restock,
+                                        minimum_age,
+                                        0,
+                                        NULL,
+                                        cb,
+                                        cb_cls);
+}
+
+
+struct TALER_MERCHANT_ProductsPostHandle *
 TALER_MERCHANT_products_post (
   struct GNUNET_CURL_Context *ctx,
   const char *backend_url,