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Allow selecting fragment source with columns #4760

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Merged
greg-rychlewski merged 3 commits into from
Jul 21, 2026
+19 −5
Merged

Allow selecting fragment source with columns #4760

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6b88c49
allow selecting fragment source with columns
greg-rychlewski Jul 21, 2026
5d06a69
update test
greg-rychlewski Jul 21, 2026
bbf48d6
fixes
greg-rychlewski Jul 21, 2026
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16 changes: 12 additions & 4 deletions lib/ecto/query/planner.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -1282,8 +1282,11 @@ defmodule Ecto.Query.Planner do
error!(query, "queries that do not have a schema need to explicitly pass a :select clause")
end

def ensure_select(%{select: nil, from: %{source: {:fragment, _, _}}} = query, true) do
error!(query, "queries from a fragment need to explicitly pass a :select clause")
def ensure_select(%{select: nil, from: %{source: {:fragment, [], _}}} = query, true) do
error!(
query,
"queries from a fragment need to explicitly pass a :select clause or use the `:columns` option"
)
end

def ensure_select(%{select: nil} = query, true) do
Expand Down Expand Up @@ -2248,8 +2251,13 @@ defmodule Ecto.Query.Planner do
{{:map, Enum.map(fields, &{&1, {:value, :any}})},
Enum.map(fields, &select_field(&1, ix, :always))}

{:error, {:fragment, _, _}} ->
{{:value, :map}, [{:&, [], [ix]}]}
{:error, {:fragment, meta, _}} ->
if columns = meta[:column_names] do
{{:map, Enum.map(columns, &{&1, {:value, :any}})},
Enum.map(columns, &select_field(&1, ix, :always))}
Comment on lines +2255 to +2257

@greg-rychlewski greg-rychlewski Jul 21, 2026

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@josevalim Sorry while making your change I actually noticed we already had a way to handle map creation without adding a new {:source, :fragment, ...} construct. Just letting you take a look again before mering

else
{{:value, :map}, [{:&, [], [ix]}]}
end

{:error, {:values, _, [types, _]}} ->
fields = Keyword.keys(types)
Expand Down
6 changes: 6 additions & 0 deletions test/ecto/query/planner_test.exs
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Expand Up @@ -2502,6 +2502,12 @@ defmodule Ecto.Query.PlannerTest do
end
end

test "normalize: select source on fragment with columns" do
query = from f in fragment("select 1", columns: [:x])
{_, _, _, select} = normalize_with_params(query)
assert %{from: {_, {:map, [x: {:value, :any}]}}} = select
end

test "normalize: select with map/2" do
query = Post |> select([p], map(p, [:id, :title])) |> normalize()
assert query.select.expr == {:&, [], [0]}
Expand Down
2 changes: 1 addition & 1 deletion test/ecto/query/subquery_test.exs
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Expand Up @@ -288,7 +288,7 @@ defmodule Ecto.Query.SubqueryTest do

test "raises on fragment source without :select" do
query = from f in fragment("select 1 as x")
assert_raise Ecto.SubQueryError, ~r/queries from a fragment need to explicitly pass a :select clause in query/, fn ->
assert_raise Ecto.SubQueryError, ~r/queries from a fragment need to explicitly pass a :select clause/, fn ->
plan(from(subquery(query), []))
end
end
Expand Down
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