Alias seems to break query

Library Version

3.0.0

.NET Runtime

.NET Core 5.0.406

Operating System / Device Details

Ubuntu 20.04

Log Output

2022-4-8 12:18:20.776+02:00 [1]| INFO) [Database] (Startup) [1] CouchbaseLite/3.0.0 (.NET; Linux 5.13.0-39-generic #44~20.04.1-Ubuntu SMP Thu Mar 24 16:43:35 UTC 2022) Build/124 LiteCore/b018a12db01222d451b4f7b95478d4825bc19954 (191) Commit/f733cb70 2022-4-8 12:18:20.795+02:00 [1]| WARNING) [Database] (Logging) [1] Database.Log.File.Config is null, meaning file logging is disabled. Log files required for product support are not being generated. 2022-4-8 12:18:20.894+02:00 [1]| ERROR) [Database] SQLite error (code 1): no such column: Label2 in "SELECT fl_result(fl_value(machines.body, ‘Id’)), fl_result(fl_value(machines.body, ‘Label’)) AS Label2, fl_result(fl_value(machines.body, ‘ModelId’)), fl_result(Label2) AS ModelLabel 2022-4-8 12:18:20.895+02:00 [1]| ERROR) [Database] no such column: Label2 (1/1) 2022-4-8 12:18:20.895+02:00 [1]| WARNING) [Database] {DB#1} SQLite error compiling statement “SELECT fl_result(fl_value(machines.body, ‘Id’)), fl_result(fl_value(machines.body, ‘Label’)) AS Label2, fl_result(fl_value(machines.body, ‘ModelId’)), fl_result(Label2) AS ModelLabel FROM kv_default AS machines LEFT OUTER JOIN kv_default AS models ON (fl_value(models.body, ‘Id’) = fl_value(machines.body, ‘ModelId’)) AND (models.flags & 1 = 0) WHERE (fl_value(machines.body, ‘Type’) = ‘machine’ AND (fl_value(machines.body, ‘Disabled’) = fl_bool(0) OR NOT (isvalued(fl_value(machines.body, ‘Disabled’))))) AND (machines.flags & 1 = 0)”: no such column: Label2 Unhandled exception. Couchbase.Lite.CouchbaseSQLiteException: CouchbaseLiteException (SQLiteDomain / 1): no such column: Label2. at LiteCore.Interop.NativeHandler.ThrowOrHandle() at LiteCore.Interop.NativeHandler.Execute(C4TryLogicDelegate1 block) at LiteCore.LiteCoreBridge.Check(C4TryLogicDelegate1 block) at Couchbase.Lite.Support.ThreadSafety.DoLockedBridge(C4TryLogicDelegate1 a) at Couchbase.Lite.Internal.Query.XQuery.Check() at Couchbase.Lite.Internal.Query.XQuery.Explain() at CouchbaseJoinBug.Program.Main(String[] args) in /home/quentin/Temps/CouchbaseJoinBug/Program.cs:line 71

Expected behavior

The query should return what it is expected ^^.

Actual behavior

It fails

Steps To Reproduce

if you alias a property to the name of another property that comes later in the query, it fails

using (var query = QueryBuilder.Select(
  SelectResult.Expression(Expression.Property(nameof(MachineDTO.Label)).From(MACHINES)).As("Label2"), // removing alias or putting an other value fix the issue
  SelectResult.Expression(Expression.Property(nameof(ModelDTO.Label2)).From(MODELS)).As("ModelLabel")

Reproduction Project

https://github.com/Billuc/CouchbaseJoinBug

[Billuc]

Hi, Thanks for your answer !

We didn’t have any issue previously. It appeared when we upgraded Couchbase Lite from version 2.7.0 to 3.0.0. Do you have any idea as to why everything was fine previously and it breaks now ? Is it wanted ?

BTW, we kinda solved our problem by specifically not aliasing variables that don’t need it. For instance, instead of writing

SELECT
    machines.Label AS Label,
    models.Label As ModelLabel

we just write

SELECT
    machines.Label,
    models.Label AS ModelLabel

The 2 snippets ultimately do the same thing (we get the Machine Label named as Label and the Model Label named as ModelLabel) but the second does not throw an exception.

[Sandychuang8]

This indeed is a LiteCore issue and it is triaged under https://github.com/couchbase/couchbase-lite-core/issues/1444