Big refactor of generated code

- Stop generating helper functions for each model
- Move Insert/Update/Upsert query generation helpers to strmangle
- Add tests for query generation helpers
- Delete a lot of the Insert/Upsert tests that test the query generation
  helpers.
- Use tx for more of the tests.

templates/singleton/boil_helpers.tpl

@@ -11,3 +11,46 @@ func NewQuery(exec boil.Executor, mods ...qm.QueryMod) *boil.Query {
 
 	return q
 }
+
+// generateUpsertQuery builds a SQL statement string using the upsertData provided.
+func generateUpsertQuery(tableName string, updateOnConflict bool, ret, update, conflict, whitelist []string) string {
+  conflict = strmangle.IdentQuoteSlice(conflict)
+  whitelist = strmangle.IdentQuoteSlice(whitelist)
+  ret = strmangle.IdentQuoteSlice(ret)
+
+	buf := strmangle.GetBuffer()
+	defer strmangle.PutBuffer(buf)
+
+  fmt.Fprintf(
+		buf,
+    "INSERT INTO %s (%s) VALUES (%s) ON CONFLICT ",
+		tableName,
+    strings.Join(whitelist, ", "),
+    strmangle.Placeholders(len(whitelist), 1, 1),
+  )
+
+  if !updateOnConflict {
+    buf.WriteString("DO NOTHING")
+  } else {
+		buf.WriteByte('(')
+		buf.WriteString(strings.Join(conflict, ", "))
+		buf.WriteString(") DO UPDATE SET")
+
+	  for i, v := range update {
+			if i != 0 {
+				buf.WriteByte(',')
+			}
+	    quoted := strmangle.IdentQuote(v)
+			buf.WriteString(quoted)
+			buf.WriteString(" = EXCLUDED.")
+			buf.WriteString(quoted)
+	  }
+  }
+
+  if len(ret) != 0 {
+		buf.WriteString(" RETURNING ")
+		buf.WriteString(strings.Join(ret, ", "))
+  }
+
+  return buf.String()
+}

templates/singleton/boil_types.tpl

@@ -1,13 +1,6 @@
 // M type is for providing columns and column values to UpdateAll.
 type M map[string]interface{}
 
-type upsertData struct {
-  conflict  []string
-  update    []string
-  whitelist []string
-  returning []string
-}
-
 // ErrSyncFail occurs during insert when the record could not be retrieved in
 // order to populate default value information. This usually happens when LastInsertId
 // fails or there was a primary key configuration that was not resolvable.