mod_storage_sql: Delay showing SQL library error until attempted load

This should ensure that e.g. failure to load LuaSQLite3 is not logged
unless it is needed, since module failures are very verbose.

Closes #1919

1 files changed, 17 insertions, 13 deletions

diff --git a/plugins/mod_storage_sql.lua b/plugins/mod_storage_sql.lua
index f053f729..f215ef65 100644
--- a/plugins/mod_storage_sql.lua
+++ b/plugins/mod_storage_sql.lua
@@ -13,20 +13,24 @@ local t_concat = table.concat;
 
 local have_dbisql, dbisql = pcall(require, "prosody.util.sql");
 local have_sqlite, sqlite = pcall(require, "prosody.util.sqlite3");
-if not have_dbisql then
-	module:log("debug", "Could not load LuaDBI: %s", dbisql)
-	dbisql = nil;
-end
-if not have_sqlite then
-	module:log("debug", "Could not load LuaSQLite3: %s", sqlite)
-	sqlite = nil;
-end
 if not (have_dbisql or have_sqlite) then
 	module:log("error", "LuaDBI or LuaSQLite3 are required for using SQL databases but neither are installed");
 	module:log("error", "Please install at least one of LuaDBI and LuaSQLite3. See https://prosody.im/doc/depends");
+	module:log("debug", "Could not load LuaDBI: %s", dbisql);
+	module:log("debug", "Could not load LuaSQLite3: %s", sqlite);
 	error("No SQL library available")
 end
 
+local function get_sql_lib(driver)
+	if driver == "SQLite3" and have_sqlite then
+		return sqlite;
+	elseif have_dbisql then
+		return dbisql;
+	else
+		error(dbisql);
+	end
+end
+
 local noop = function() end
 local unpack = table.unpack;
 local function iterator(result)
@@ -757,7 +761,7 @@ end
 
 
 local function create_table(engine) -- luacheck: ignore 431/engine
-	local sql = engine.params.driver == "SQLite3" and sqlite or dbisql;
+	local sql = get_sql_lib(engine.params.driver);
 	local Table, Column, Index = sql.Table, sql.Column, sql.Index;
 
 	local ProsodyTable = Table {
@@ -798,7 +802,7 @@ end
 local function upgrade_table(engine, params, apply_changes) -- luacheck: ignore 431/engine
 	local changes = false;
 	if params.driver == "MySQL" then
-		local sql = dbisql;
+		local sql = get_sql_lib("MySQL");
 		local success,err = engine:transaction(function()
 			do
 				local result = assert(engine:execute("SHOW COLUMNS FROM \"prosody\" WHERE \"Field\"='value' and \"Type\"='text'"));
@@ -920,7 +924,7 @@ end
 function module.load()
 	local engines = module:shared("/*/sql/connections");
 	local params = normalize_params(module:get_option("sql", default_params));
-	local sql = params.driver == "SQLite3" and sqlite or dbisql;
+	local sql = get_sql_lib(params.driver);
 	local db_uri = sql.db2uri(params);
 	engine = engines[db_uri];
 	if not engine then
@@ -1012,7 +1016,7 @@ function module.command(arg)
 		local uris = {};
 		for host in pairs(prosody.hosts) do -- luacheck: ignore 431/host
 			local params = normalize_params(config.get(host, "sql") or default_params);
-			local sql = engine.params.driver == "SQLite3" and sqlite or dbisql;
+			local sql = get_sql_lib(engine.params.driver);
 			uris[sql.db2uri(params)] = params;
 		end
 		print("We will check and upgrade the following databases:\n");
@@ -1028,7 +1032,7 @@ function module.command(arg)
 		-- Upgrade each one
 		for _, params in pairs(uris) do
 			print("Checking "..params.database.."...");
-			local sql = params.driver == "SQLite3" and sqlite or dbisql;
+			local sql = get_sql_lib(params.driver);
 			engine = sql:create_engine(params);
 			upgrade_table(engine, params, true);
 		end