api: return error if no tuples/objects

Before this patch, the behavior of `*_many` requests if empty array of
tuples/objects were rather confusing. For example, due to format
processing all `*_object_many` operations resulted in `nil, {}` --
error request with zero errors. `insert_many` and `replace_many` calls
result in `nil, nil` -- no result, no error. `upsert_many` results in
`{metadata = metadata}, nil` with no `rows` in response. Thus, for all
six `*_many` calls trying to execute the request with empty array on
input result in malformed response.

After this patch, trying to run `*_many` request with empty array of
tuples/objects will result in `nil, {err}`, similar to existing
`*_many` API. Single tuple crud API already does not allow to run with
no tuples/objects.

Closes #377

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 * `deps.sh` installs the `vshard` instead of the `cartridge` by default (#364).
   You could to specify an environment variable `CARTIRDGE_VERSION` to install
   the `cartridge` and run tests cases with it.
+* Return explicit error for `*_many` call with no tuples/objects (#377).
 
 ### Fixed
 * `crud.readview` resource cleanup on garbage collect (#379).

README.md

@@ -288,7 +288,7 @@ local result, err = crud.insert_object_many(space_name, objects, opts)
 where:
 
 * `space_name` (`string`) - name of the space to insert an object
-* `tuples` / `objects` (`table`) - array of tuples/objects to insert
+* `tuples` / `objects` (`table`) - array of tuples/objects to insert (at least one)
 * `opts`:
   * `timeout` (`?number`) - `vshard.call` timeout and vshard master
     discovery timeout (in seconds), default value is 2
@@ -639,7 +639,7 @@ local result, err = crud.replace_object_many(space_name, objects, opts)
 where:
 
 * `space_name` (`string`) - name of the space to insert/replace an object
-* `tuples` / `objects` (`table`) - array of tuples/objects to replace
+* `tuples` / `objects` (`table`) - array of tuples/objects to replace (at least one)
 * `opts`:
   * `timeout` (`?number`) - `vshard.call` timeout and vshard master
     discovery timeout (in seconds), default value is 2
@@ -855,7 +855,7 @@ where:
 * `tuples_operation_data` / `objects_operation_data` (`table`) - array of
    tuples/objects to insert
    and update [operations](https://www.tarantool.io/en/doc/latest/reference/reference_lua/box_space/#box-space-update)
-   in format {{tuple_1, operation_1}, ..., {tuple_n, operation_n}},
+   in format {{tuple_1, operation_1}, ..., {tuple_n, operation_n}} (at least one),
    if there is tuple with duplicate key then existing tuple will
    be updated with update operations
 * `opts`:

crud/insert_many.lua

@@ -244,6 +244,10 @@ function insert_many.tuples(space_name, tuples, opts)
         fetch_latest_metadata = '?boolean',
     })
 
+    if next(tuples) == nil then
+        return nil, {InsertManyError:new("At least one tuple expected")}
+    end
+
     opts = opts or {}
 
     local vshard_router, err = utils.get_vshard_router_instance(opts.vshard_router)
@@ -284,6 +288,10 @@ function insert_many.objects(space_name, objs, opts)
         fetch_latest_metadata = '?boolean',
     })
 
+    if next(objs) == nil then
+        return nil, {InsertManyError:new("At least one object expected")}
+    end
+
     opts = opts or {}
 
     local vshard_router, err = utils.get_vshard_router_instance(opts.vshard_router)

crud/replace_many.lua

@@ -247,6 +247,10 @@ function replace_many.tuples(space_name, tuples, opts)
         fetch_latest_metadata = '?boolean',
     })
 
+    if next(tuples) == nil then
+        return nil, {ReplaceManyError:new("At least one tuple expected")}
+    end
+
     opts = opts or {}
 
     local vshard_router, err = utils.get_vshard_router_instance(opts.vshard_router)
@@ -287,6 +291,10 @@ function replace_many.objects(space_name, objs, opts)
         fetch_latest_metadata = '?boolean',
     })
 
+    if next(objs) == nil then
+        return nil, {ReplaceManyError:new("At least one object expected")}
+    end
+
     opts = opts or {}
 
     local vshard_router, err = utils.get_vshard_router_instance(opts.vshard_router)

crud/upsert_many.lua

@@ -263,6 +263,10 @@ function upsert_many.tuples(space_name, tuples_operation_data, opts)
         fetch_latest_metadata = '?boolean',
     })
 
+    if next(tuples_operation_data) == nil then
+        return nil, {UpsertManyError:new("At least one tuple expected")}
+    end
+
     opts = opts or {}
 
     local vshard_router, err = utils.get_vshard_router_instance(opts.vshard_router)
@@ -303,6 +307,10 @@ function upsert_many.objects(space_name, objs_operation_data, opts)
         fetch_latest_metadata = '?boolean',
     })
 
+    if next(objs_operation_data) == nil then
+        return nil, {UpsertManyError:new("At least one object expected")}
+    end
+
     opts = opts or {}
 
     local vshard_router, err = utils.get_vshard_router_instance(opts.vshard_router)

test/integration/insert_many_test.lua

@@ -2032,3 +2032,23 @@ pgroup.test_noreturn_opt = function(g)
     t.assert_equals(#errs, 3)
     t.assert_equals(result, nil)
 end
+
+pgroup.test_zero_tuples = function(g)
+    local result, errs = g.cluster.main_server.net_box:call(
+        'crud.insert_many', {'customers', {}})
+
+    t.assert_not_equals(errs, nil)
+    t.assert_equals(#errs, 1)
+    t.assert_str_contains(errs[1].err, "At least one tuple expected")
+    t.assert_equals(result, nil)
+end
+
+pgroup.test_zero_objects = function(g)
+    local result, errs = g.cluster.main_server.net_box:call(
+        'crud.insert_object_many', {'customers', {}})
+
+    t.assert_not_equals(errs, nil)
+    t.assert_equals(#errs, 1)
+    t.assert_str_contains(errs[1].err, "At least one object expected")
+    t.assert_equals(result, nil)
+end

test/integration/replace_many_test.lua

@@ -2043,3 +2043,23 @@ pgroup.test_noreturn_opt = function(g)
     t.assert_equals(#errs, 3)
     t.assert_equals(result, nil)
 end
+
+pgroup.test_zero_tuples = function(g)
+    local result, errs = g.cluster.main_server.net_box:call(
+        'crud.replace_many', {'customers', {}})
+
+    t.assert_not_equals(errs, nil)
+    t.assert_equals(#errs, 1)
+    t.assert_str_contains(errs[1].err, "At least one tuple expected")
+    t.assert_equals(result, nil)
+end
+
+pgroup.test_zero_objects = function(g)
+    local result, errs = g.cluster.main_server.net_box:call(
+        'crud.replace_object_many', {'customers', {}})
+
+    t.assert_not_equals(errs, nil)
+    t.assert_equals(#errs, 1)
+    t.assert_str_contains(errs[1].err, "At least one object expected")
+    t.assert_equals(result, nil)
+end

test/integration/upsert_many_test.lua

@@ -2044,3 +2044,23 @@ pgroup.test_noreturn_opt = function(g)
     t.assert_equals(#errs, 3)
     t.assert_equals(result, nil)
 end
+
+pgroup.test_zero_tuples = function(g)
+    local result, errs = g.cluster.main_server.net_box:call(
+        'crud.upsert_many', {'customers', {}})
+
+    t.assert_not_equals(errs, nil)
+    t.assert_equals(#errs, 1)
+    t.assert_str_contains(errs[1].err, "At least one tuple expected")
+    t.assert_equals(result, nil)
+end
+
+pgroup.test_zero_objects = function(g)
+    local result, errs = g.cluster.main_server.net_box:call(
+        'crud.upsert_object_many', {'customers', {}})
+
+    t.assert_not_equals(errs, nil)
+    t.assert_equals(#errs, 1)
+    t.assert_str_contains(errs[1].err, "At least one object expected")
+    t.assert_equals(result, nil)
+end