ocean · ocean · Dec 17, 2025 · Dec 17, 2025 · Dec 17, 2025 · Dec 17, 2025
diff --git a/.dialyzer_ignore.exs b/.dialyzer_ignore.exs
@@ -0,0 +1,25 @@
+{"lib/ecto/adapters/libsql.ex", "Function rollback/2 has no local return."}
+{"lib/ecto/adapters/libsql.ex", "The pattern can never match the type
+  {:error, %EctoLibSql.Error{:__exception__ => true, :message => _, :sqlite => nil},
+   %EctoLibSql.State{:conn_id => _, _ => _}}
+  | {:ok, %EctoLibSql.Query{:statement => _, _ => _},
+     %EctoLibSql.Result{
+       :columns => _,
+       :command =>
+         :begin
+         | :commit
+         | :create
+         | :delete
+         | :insert
+         | :rollback
+         | :select
+         | :unknown
+         | :update,
+       :num_rows => _,
+       :rows => _
+     }, %EctoLibSql.State{:conn_id => _, _ => _}}
+."}
+{"lib/ecto/adapters/libsql.ex", "Type mismatch for @callback dump_cmd."}
+{"lib/ecto/adapters/libsql/connection.ex", "Spec type mismatch in argument to callback to_constraints."}
+{"lib/ecto/adapters/libsql/connection.ex", "Type mismatch with behaviour callback to explain_query/4."}
+{"lib/ecto/adapters/libsql/connection.ex", "List construction (cons) will produce an improper list, because its second argument is <<_::64>>."}
diff --git a/.gitignore b/.gitignore
@@ -30,6 +30,9 @@ ecto_libsql-*.tar
 /priv/native/*.dll
 /priv/native/*.dylib
 
+# Erlang PLTs for Dialyzer
+/priv/plts/
+
 # Test databases
 z_ecto_libsql_test-*.db
 z_ecto_libsql_test-*.db-*

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -5,6 +5,21 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- **Constraint Error Handling: Index Name Reconstruction (Issue #34)**
+  - Improved constraint name extraction to reconstruct full index names from SQLite error messages
+  - Now follows Ecto's naming convention: `table_column1_column2_index`
+  - **Single-column constraints**: `"UNIQUE constraint failed: users.email"` → `"users_email_index"` (previously just `"email"`)
+  - **Multi-column constraints**: `"UNIQUE constraint failed: users.slug, users.parent_slug"` → `"users_slug_parent_slug_index"`
+  - **Backtick handling**: Properly strips trailing backticks appended by libSQL to error messages
+  - **Enhanced error messages**: Preserves custom index names from enhanced format `(index: custom_index_name)`
+  - **NOT NULL constraints**: Reconstructs index names following same convention
+  - Enables accurate `unique_constraint/3` and `check_constraint/3` matching with custom index names in Ecto changesets
+  - Added comprehensive test coverage for all constraint scenarios (4 new tests)
+
 ## [0.8.0] - 2025-12-17
 
 ### Changed

diff --git a/lib/ecto/adapters/libsql/connection.ex b/lib/ecto/adapters/libsql/connection.ex
@@ -66,6 +66,21 @@ defmodule Ecto.Adapters.LibSql.Connection do
   end
 
   @impl true
+  @doc """
+  Parse a SQLite error message and map it to a list of Ecto constraint tuples.
+
+  Accepts an exception-like map containing a SQLite error `:message` and returns recognised constraint information such as unique, foreign_key or check constraints; returns an empty list when no known constraint pattern is found.
+
+  ## Parameters
+
+    - error: Map containing a `:message` string produced by SQLite.
+    - _opts: Options (unused).
+
+  ## Returns
+
+    - A keyword list of constraint tuples, for example `[unique: "table_column_index"]`, `[foreign_key: :unknown]`, `[check: "constraint_name"]`, or `[]` when no constraint is recognised.
+  """
+  @spec to_constraints(%{message: String.t()}, Keyword.t()) :: Keyword.t()
   def to_constraints(%{message: message}, _opts) do
     cond do
       String.contains?(message, "UNIQUE constraint failed") ->
@@ -87,36 +102,71 @@ defmodule Ecto.Adapters.LibSql.Connection do
   end
 
   defp extract_constraint_name(message) do
-    # Extract constraint name from SQLite error messages
+    # Extract constraint name from SQLite error messages.
     #
     # SQLite only reports column names in constraint errors, not index names.
-    # However, ecto_libsql enhances error messages to include the actual index name
-    # by querying SQLite metadata. This allows users to use custom index names in
-    # their changesets with unique_constraint/3.
-    #
-    # Enhanced format (when index is found):
-    #   "UNIQUE constraint failed: users.email (index: users_email_index)" -> "users_email_index"
+    # We reconstruct the index name following Ecto's naming convention:
+    #   table_column1_column2_index
     #
-    # Standard formats (fallback to column name):
-    #   "UNIQUE constraint failed: users.email" -> "email"
-    #   "NOT NULL constraint failed: users.name" -> "name"
-    #   "UNIQUE constraint failed: users.slug, users.parent_slug" -> "slug"
+    # Examples:
+    #   "UNIQUE constraint failed: users.email" -> "users_email_index"
+    #   "UNIQUE constraint failed: users.slug, users.parent_slug" -> "users_slug_parent_slug_index"
+    #   "NOT NULL constraint failed: users.name" -> "users_name_index"
+    #   "CHECK constraint failed: positive_age" -> "positive_age"
     #
-    # First, try to extract the index name from enhanced error messages
+    # First, try to extract the index name from enhanced error messages (if present)
     case Regex.run(~r/\(index: ([\w_]+)\)/, message) do
       [_, index_name] ->
         # Found enhanced error with actual index name
         index_name
 
       nil ->
-        # No index name in message, fall back to column name extraction
-        case Regex.run(~r/constraint failed: (?:\w+\.)?(\w+)/, message) do
-          [_, name] -> name
-          _ -> "unknown"
+        # No index name in message, reconstruct from column names
+        case Regex.run(~r/constraint failed: (.+)$/, message) do
+          [_, constraint_part] ->
+            # Strip any trailing backticks that libSQL might add to error messages
+            cleaned = constraint_part |> String.trim() |> String.trim_trailing("`")
+            constraint_name_hack(cleaned)
+
+          _ ->
+            "unknown"
         end
     end
   end
 
+  # Reconstruct index names from SQLite constraint error messages.
+  # This follows Ecto's convention: table_column1_column2_index
+  defp constraint_name_hack(constraint) do
+    # Helper to clean backticks from identifiers (libSQL sometimes adds them)
+    clean = fn s -> String.trim(s, "`") end
+
+    if String.contains?(constraint, ", ") do
+      # Multi-column constraint: "table.col1, table.col2" -> "table_col1_col2_index"
+      [first | rest] = String.split(constraint, ", ")
+
+      table_col = first |> clean.() |> String.replace(".", "_")
+
+      cols =
+        Enum.map(rest, fn col ->
+          col |> clean.() |> String.split(".") |> List.last()
+        end)
+
+      [table_col | cols] |> Enum.concat(["index"]) |> Enum.join("_")
+    else
+      if String.contains?(constraint, ".") do
+        # Single column: "table.column" -> "table_column_index"
+        constraint
+        |> clean.()
+        |> String.split(".")
+        |> Enum.concat(["index"])
+        |> Enum.join("_")
+      else
+        # No table prefix (e.g., CHECK constraint name): return as-is
+        clean.(constraint)
+      end
+    end
+  end
+
   ## DDL Generation
 
   @impl true

diff --git a/mix.exs b/mix.exs
@@ -16,7 +16,17 @@ defmodule EctoLibSql.MixProject do
       homepage_url: @source_url,
       package: package(),
       description: description(),
-      docs: docs()
+      docs: docs(),
+      dialyzer: [
+        plt_core_path: "priv/plts",
+        app_tree: true,
+        plt_add_apps: [:mix, :ex_unit],
+        ignore_warnings: ".dialyzer_ignore.exs",
+        list_unused_filters: true
+      ],
+      aliases: [
+        "check.dialyzer": "dialyzer"
+      ]
     ]
   end
 
@@ -38,12 +48,13 @@ defmodule EctoLibSql.MixProject do
 
   defp deps do
     [
-      {:rustler, "~> 0.37.1"},
       {:db_connection, "~> 2.1"},
+      {:dialyxir, "~> 1.4", only: [:dev], runtime: false},
       {:ecto, "~> 3.11"},
       {:ecto_sql, "~> 3.11"},
       {:ex_doc, "~> 0.31", only: :dev, runtime: false},
-      {:jason, "~> 1.4"}
+      {:jason, "~> 1.4"},
+      {:rustler, "~> 0.37.1"}
     ]
   end
 

diff --git a/mix.lock b/mix.lock
@@ -1,9 +1,11 @@
 %{
   "db_connection": {:hex, :db_connection, "2.8.1", "9abdc1e68c34c6163f6fb96a96532272d13ad7ca45262156ae8b7ec6d9dc4bec", [:mix], [{:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "a61a3d489b239d76f326e03b98794fb8e45168396c925ef25feb405ed09da8fd"},
   "decimal": {:hex, :decimal, "2.3.0", "3ad6255aa77b4a3c4f818171b12d237500e63525c2fd056699967a3e7ea20f62", [:mix], [], "hexpm", "a4d66355cb29cb47c3cf30e71329e58361cfcb37c34235ef3bf1d7bf3773aeac"},
+  "dialyxir": {:hex, :dialyxir, "1.4.7", "dda948fcee52962e4b6c5b4b16b2d8fa7d50d8645bbae8b8685c3f9ecb7f5f4d", [:mix], [{:erlex, ">= 0.2.8", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "b34527202e6eb8cee198efec110996c25c5898f43a4094df157f8d28f27d9efe"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.44", "f20830dd6b5c77afe2b063777ddbbff09f9759396500cdbe7523efd58d7a339c", [:mix], [], "hexpm", "4778ac752b4701a5599215f7030989c989ffdc4f6df457c5f36938cc2d2a2750"},
   "ecto": {:hex, :ecto, "3.13.5", "9d4a69700183f33bf97208294768e561f5c7f1ecf417e0fa1006e4a91713a834", [:mix], [{:decimal, "~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "df9efebf70cf94142739ba357499661ef5dbb559ef902b68ea1f3c1fabce36de"},
   "ecto_sql": {:hex, :ecto_sql, "3.13.3", "81f7067dd1951081888529002dbc71f54e5e891b69c60195040ea44697e1104a", [:mix], [{:db_connection, "~> 2.4.1 or ~> 2.5", [hex: :db_connection, repo: "hexpm", optional: false]}, {:ecto, "~> 3.13.0", [hex: :ecto, repo: "hexpm", optional: false]}, {:myxql, "~> 0.7", [hex: :myxql, repo: "hexpm", optional: true]}, {:postgrex, "~> 0.19 or ~> 1.0", [hex: :postgrex, repo: "hexpm", optional: true]}, {:tds, "~> 2.1.1 or ~> 2.2", [hex: :tds, repo: "hexpm", optional: true]}, {:telemetry, "~> 0.4.0 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "5751caea36c8f5dd0d1de6f37eceffea19d10bd53f20e5bbe31c45f2efc8944a"},
+  "erlex": {:hex, :erlex, "0.2.8", "cd8116f20f3c0afe376d1e8d1f0ae2452337729f68be016ea544a72f767d9c12", [:mix], [], "hexpm", "9d66ff9fedf69e49dc3fd12831e12a8a37b76f8651dd21cd45fcf5561a8a7590"},
   "ex_doc": {:hex, :ex_doc, "0.39.3", "519c6bc7e84a2918b737aec7ef48b96aa4698342927d080437f61395d361dcee", [:mix], [{:earmark_parser, "~> 1.4.44", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_c, ">= 0.1.0", [hex: :makeup_c, repo: "hexpm", optional: true]}, {:makeup_elixir, "~> 0.14 or ~> 1.0", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1 or ~> 1.0", [hex: :makeup_erlang, repo: "hexpm", optional: false]}, {:makeup_html, ">= 0.1.0", [hex: :makeup_html, repo: "hexpm", optional: true]}], "hexpm", "0590955cf7ad3b625780ee1c1ea627c28a78948c6c0a9b0322bd976a079996e1"},
   "jason": {:hex, :jason, "1.4.4", "b9226785a9aa77b6857ca22832cffa5d5011a667207eb2a0ad56adb5db443b8a", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "c5eb0cab91f094599f94d55bc63409236a8ec69a21a67814529e8d5f6cc90b3b"},
   "makeup": {:hex, :makeup, "1.2.1", "e90ac1c65589ef354378def3ba19d401e739ee7ee06fb47f94c687016e3713d1", [:mix], [{:nimble_parsec, "~> 1.4", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "d36484867b0bae0fea568d10131197a4c2e47056a6fbe84922bf6ba71c8d17ce"},

diff --git a/test/ecto_connection_test.exs b/test/ecto_connection_test.exs
@@ -413,8 +413,8 @@ defmodule Ecto.Adapters.LibSql.ConnectionTest do
       error = %{message: "UNIQUE constraint failed: users.email"}
       constraints = Connection.to_constraints(error, [])
 
-      # Returns string constraint names to match Ecto changeset format
-      assert [unique: "email"] = constraints
+      # Reconstructs index name following Ecto's naming convention: table_column_index
+      assert [unique: "users_email_index"] = constraints
     end
 
     test "converts FOREIGN KEY constraint errors" do
@@ -438,6 +438,38 @@ defmodule Ecto.Adapters.LibSql.ConnectionTest do
 
       assert [] = constraints
     end
+
+    test "converts multi-column UNIQUE constraint errors" do
+      error = %{message: "UNIQUE constraint failed: users.slug, users.parent_slug"}
+      constraints = Connection.to_constraints(error, [])
+
+      # Reconstructs index name from multiple columns: table_col1_col2_index
+      assert [unique: "users_slug_parent_slug_index"] = constraints
+    end
+
+    test "converts NOT NULL constraint errors" do
+      error = %{message: "NOT NULL constraint failed: users.name"}
+      constraints = Connection.to_constraints(error, [])
+
+      # NOT NULL constraints are reported as check constraints with reconstructed index name
+      assert [check: "users_name_index"] = constraints
+    end
+
+    test "handles backticks in constraint error messages" do
+      error = %{message: "UNIQUE constraint failed: users.email`"}
+      constraints = Connection.to_constraints(error, [])
+
+      # Properly strips backticks appended by libSQL
+      assert [unique: "users_email_index"] = constraints
+    end
+
+    test "preserves enhanced error messages with index name" do
+      error = %{message: "UNIQUE constraint failed: users.email (index: custom_email_index)"}
+      constraints = Connection.to_constraints(error, [])
+
+      # Uses the provided index name from enhanced error
+      assert [unique: "custom_email_index"] = constraints
+    end
   end
 
   describe "on_conflict insert" do

diff --git a/test/ecto_integration_test.exs b/test/ecto_integration_test.exs
@@ -30,7 +30,7 @@ defmodule Ecto.Integration.EctoLibSqlTest do
       |> cast(attrs, [:name, :email, :age, :active, :balance, :bio])
       |> validate_required([:name, :email])
       |> validate_format(:email, ~r/@/)
-      |> unique_constraint(:email, name: "email")
+      |> unique_constraint(:email, name: "users_email_index")
     end
   end