MM-38698: Add limit to the CLI compliance export command (#20997)

```release-note
A batchSize option has been added to the mattermost export
CLI command to limit the number of items exported. By default,
if it is not included, it exports all the posts.
```

https://mattermost.atlassian.net/browse/MM-38698


Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

cmd/mattermost/commands/export.go

@@ -71,9 +71,13 @@ func init() {
 	ScheduleExportCmd.Flags().Int("timeoutSeconds", -1, "The maximum number of seconds to wait for the job to complete before timing out.")
 
 	CsvExportCmd.Flags().Int64("exportFrom", -1, "The timestamp of the earliest post to export, expressed in seconds since the unix epoch.")
+	CsvExportCmd.Flags().Int("limit", -1, "The number of posts to export. The default of -1 means no limit.")
 
 	ActianceExportCmd.Flags().Int64("exportFrom", -1, "The timestamp of the earliest post to export, expressed in seconds since the unix epoch.")
+	ActianceExportCmd.Flags().Int("limit", -1, "The number of posts to export. The default of -1 means no limit.")
+
 	GlobalRelayZipExportCmd.Flags().Int64("exportFrom", -1, "The timestamp of the earliest post to export, expressed in seconds since the unix epoch.")
+	GlobalRelayZipExportCmd.Flags().Int("limit", -1, "The number of posts to export. The default of -1 means no limit.")
 
 	BulkExportCmd.Flags().Bool("all-teams", true, "Export all teams from the server.")
 	BulkExportCmd.Flags().Bool("attachments", false, "Also export file attachments.")
@@ -164,11 +168,16 @@ func buildExportCmdF(format string) func(command *cobra.Command, args []string)
 			return errors.New("exportFrom must be a positive integer")
 		}
 
+		limit, err := command.Flags().GetInt("limit")
+		if err != nil {
+			return errors.New("limit flag error")
+		}
+
 		if a.MessageExport() == nil || license == nil || !*license.Features.MessageExport {
 			return errors.New("message export feature not available")
 		}
 
-		warningsCount, appErr := a.MessageExport().RunExport(format, startTime)
+		warningsCount, appErr := a.MessageExport().RunExport(format, startTime, limit)
 		if appErr != nil {
 			return appErr
 		}

einterfaces/message_export.go

@@ -11,5 +11,5 @@ import (
 
 type MessageExportInterface interface {
 	StartSynchronizeJob(ctx context.Context, exportFromTimestamp int64) (*model.Job, *model.AppError)
-	RunExport(format string, since int64) (int64, *model.AppError)
+	RunExport(format string, since int64, limit int) (int64, *model.AppError)
 }

einterfaces/mocks/MessageExportInterface.go

@@ -17,20 +17,20 @@ type MessageExportInterface struct {
 	mock.Mock
 }
 
-// RunExport provides a mock function with given fields: format, since
-func (_m *MessageExportInterface) RunExport(format string, since int64) (int64, *model.AppError) {
-	ret := _m.Called(format, since)
+// RunExport provides a mock function with given fields: format, since, limit
+func (_m *MessageExportInterface) RunExport(format string, since int64, limit int) (int64, *model.AppError) {
+	ret := _m.Called(format, since, limit)
 
 	var r0 int64
-	if rf, ok := ret.Get(0).(func(string, int64) int64); ok {
-		r0 = rf(format, since)
+	if rf, ok := ret.Get(0).(func(string, int64, int) int64); ok {
+		r0 = rf(format, since, limit)
 	} else {
 		r0 = ret.Get(0).(int64)
 	}
 
 	var r1 *model.AppError
-	if rf, ok := ret.Get(1).(func(string, int64) *model.AppError); ok {
-		r1 = rf(format, since)
+	if rf, ok := ret.Get(1).(func(string, int64, int) *model.AppError); ok {
+		r1 = rf(format, since, limit)
 	} else {
 		if ret.Get(1) != nil {
 			r1 = ret.Get(1).(*model.AppError)

store/storetest/compliance_store.go

@@ -175,6 +175,11 @@ func testComplianceExport(t *testing.T, ss store.Store) {
 	assert.Equal(t, cposts[0].PostId, o1.Id)
 	assert.Equal(t, cposts[3].PostId, o2a.Id)
 
+	// Test limit
+	cposts, _, nErr = ss.Compliance().ComplianceExport(cr1, model.ComplianceExportCursor{}, 2)
+	require.NoError(t, nErr)
+	assert.Len(t, cposts, 2)
+
 	cr2 := &model.Compliance{Desc: "test" + model.NewId(), StartAt: o1.CreateAt - 1, EndAt: o2a.CreateAt + 1, Emails: u2.Email}
 	cposts, _, nErr = ss.Compliance().ComplianceExport(cr2, model.ComplianceExportCursor{}, limit)
 	require.NoError(t, nErr)