Add hack to fix output type for coalesce (#1119)

* Add hack to fix output type for coalesce

Add flag to skip table required check for joins when using COALESCE.

Author: kyleconroy

internal/compiler/output_columns.go

@@ -140,6 +140,7 @@ func outputColumns(qc *QueryCatalog, node ast.Node) ([]*Column, error) {
 					for _, c := range columns {
 						found = true
 						c.NotNull = true
+						c.skipTableRequiredCheck = true
 						cols = append(cols, c)
 					}
 				}
@@ -245,7 +246,7 @@ func outputColumns(qc *QueryCatalog, node ast.Node) ([]*Column, error) {
 
 	if n, ok := node.(*ast.SelectStmt); ok {
 		for _, col := range cols {
-			if !col.NotNull || col.Table == nil {
+			if !col.NotNull || col.Table == nil || col.skipTableRequiredCheck {
 				continue
 			}
 			for _, f := range n.FromClause.Items {

internal/compiler/query.go

@@ -26,6 +26,8 @@ type Column struct {
 	Scope string
 	Table *ast.TableName
 	Type  *ast.TypeName
+
+	skipTableRequiredCheck bool
 }
 
 type Query struct {

internal/endtoend/testdata/coalesce_join/postgresql/go/db.go

@@ -0,0 +1,7 @@
+CREATE TABLE foo(id bigserial primary key);
+CREATE TABLE bar(id bigserial primary key);
+
+-- name: GetBar :many
+SELECT foo.*, COALESCE(bar.id, 0) AS bar_id
+FROM foo
+LEFT JOIN bar ON foo.id = bar.id;

internal/endtoend/testdata/coalesce_join/postgresql/go/models.go

@@ -0,0 +1,12 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "path": "go",
+      "engine": "postgresql",
+      "name": "querytest",
+      "schema": "query.sql",
+      "queries": "query.sql"
+    }
+  ]
+}