Resolve: Create migration for column position change if a field position is changed in spec #58

src/db/ColumnSchema.php

@@ -25,4 +25,24 @@ class ColumnSchema extends \yii\db\ColumnSchema
      * ```
      */
     public $xDbType;
+
+    /**
+     * Used only for MySQL/MariaDB
+     * @var array|null
+     * [
+     *      index => int # position: starts from 1
+     *      after => ?string # after column
+     *      before => ?string # before column
+     * ]
+     * If `before` is null then column is last
+     * If `after` is null then column is first
+     * If both are null then table has only 1 column
+     */
+    public ?array $fromPosition = null;
+    public ?array $toPosition = null;
+
+    /**
+     * From `$this->fromPosition` and `$this->toPosition` we can check if the position is changed or not. This is done in `BaseMigrationBuilder::setColumnsPositions()`
+     */
+    public bool $isPositionChanged = false;
 }

src/generator/default/dbmodel.php

@@ -49,8 +49,8 @@
  */
 abstract class <?= $model->getClassName() ?> extends \yii\db\ActiveRecord
 {
-<?php if($scenarios = $model->getScenarios()):
-foreach($scenarios as $scenario): ?>
+<?php if ($scenarios = $model->getScenarios()):
+foreach ($scenarios as $scenario): ?>
     /**
      *<?= $scenario['description'] ?>
 
@@ -76,7 +76,7 @@ public static function tableName()
     {
         return <?= var_export($model->getTableAlias()) ?>;
     }
-<?php if($scenarios): ?>
+<?php if ($scenarios): ?>
 
     /**
      * Automatically generated scenarios from the model 'x-scenarios'.
@@ -92,7 +92,7 @@ public function scenarios()
         $default = parent::scenarios()[self::SCENARIO_DEFAULT];
 
         return [
-<?php foreach($scenarios as $scenario): ?>
+<?php foreach ($scenarios as $scenario): ?>
             self::<?= $scenario['const'] ?> => $default,
 <?php endforeach; ?>
             /**

src/lib/migrations/BaseMigrationBuilder.php

@@ -171,6 +171,7 @@ public function buildSecondary(?ManyToManyRelation $relation = null):MigrationMo
     {
         $this->migration = Yii::createObject(MigrationModel::class, [$this->model, false, $relation, []]);
         $this->newColumns = $relation->columnSchema ?? $this->model->attributesToColumnSchema();
+        $this->setColumnsPositions();
         $wantNames = array_keys($this->newColumns);
         $haveNames = $this->tableSchema->columnNames;
         $columnsForCreate = array_map(
@@ -184,7 +185,7 @@ function (string $missingColumn) {
             function (string $unknownColumn) {
                 return $this->tableSchema->columns[$unknownColumn];
             },
-            array_diff($haveNames, $wantNames)
+            array_reverse(array_diff($haveNames, $wantNames), true)
         );
 
         $columnsForChange = array_intersect($wantNames, $haveNames);
@@ -220,6 +221,7 @@ function (string $unknownColumn) {
         } else {
             $this->buildRelations();
         }
+
         return $this->migration;
     }
 
@@ -249,12 +251,12 @@ protected function buildColumnsDrop(array $columns):void
     {
         foreach ($columns as $column) {
             $tableName = $this->model->getTableAlias();
+            $position = $this->findPosition($column, true);
             if ($column->isPrimaryKey && !$column->autoIncrement) {
                 $pkName = 'pk_' . $this->model->tableName . '_' . $column->name;
                 $this->migration->addDownCode($this->recordBuilder->addPrimaryKey($tableName, [$column->name], $pkName))
                                 ->addUpCode($this->recordBuilder->dropPrimaryKey($tableName, [$column->name], $pkName));
             }
-            $position = $this->findPosition($column, true);
             $this->migration->addDownCode($this->recordBuilder->addDbColumn($tableName, $column, $position))
                             ->addUpCode($this->recordBuilder->dropColumn($tableName, $column->name));
         }
@@ -513,47 +515,6 @@ public function isDefaultValueChanged(
         return false;
     }
 
-    /**
-     * Given a column, compute its previous column name present in OpenAPI schema
-     * @return ?string
-     * `null` if column is added at last
-     * 'FIRST' if column is added at first position
-     * 'AFTER <columnName>' if column is added in between e.g. if 'email' is added after 'username' then 'AFTER username'
-     */
-    public function findPosition(ColumnSchema $column, bool $forDrop = false): ?string
-    {
-        $columnNames = array_keys($forDrop ? $this->tableSchema->columns : $this->newColumns);
-
-        $key = array_search($column->name, $columnNames);
-        if ($key > 0) {
-            $prevColName = $columnNames[$key-1];
-
-            if (!isset($columnNames[$key+1])) { // if new col is added at last then no need to add 'AFTER' SQL part. This is checked as if next column is present or not
-                return null;
-            }
-
-            // in case of `down()` code of migration, putting 'after <colName>' in add column statmenet is erroneous because <colName> may not exist.
-            // Example: From col a, b, c, d, if I drop c and d then their migration code will be generated like:
-            // `up()` code
-            // drop c
-            // drop d
-            // `down()` code
-            // add d after c (c does not exist! Error!)
-            // add c
-            if ($forDrop) {
-                return null;
-            }
-
-
-            return self::POS_AFTER . ' ' . $prevColName;
-
-        // if no `$columnSchema` is found, previous column does not exist. This happens when 'after column' is not yet added in migration or added after currently undertaken column
-        } elseif ($key === 0) {
-            return self::POS_FIRST;
-        }
-
-        return null;
-    }
 
     public function modifyDesiredFromDbInContextOfDesired(ColumnSchema $desired, ColumnSchema $desiredFromDb): void
     {
@@ -574,4 +535,19 @@ public function modifyDesiredInContextOfDesiredFromDb(ColumnSchema $desired, Col
         }
         $desired->dbType = $desiredFromDb->dbType;
     }
+
+    /**
+     * Only for MySQL and MariaDB
+     * Given a column, compute its previous column name present in OpenAPI schema
+     * @param ColumnSchema $column
+     * @param bool $forDrop
+     * @param bool $forAlter
+     * @return ?string
+     * `null` if column is added at last
+     * 'FIRST' if column is added at first position
+     * 'AFTER <columnName>' if column is added in between e.g. if 'email' is added after 'username' then 'AFTER username'
+     */
+    abstract public function findPosition(ColumnSchema $column, bool $forDrop = false, bool $forAlter = false): ?string;
+
+    abstract public function setColumnsPositions();
 }

src/lib/migrations/MigrationRecordBuilder.php

@@ -112,55 +112,63 @@ public function addDbColumn(string $tableAlias, ColumnSchema $column, ?string $p
     /**
      * @throws \yii\base\InvalidConfigException
      */
-    public function alterColumn(string $tableAlias, ColumnSchema $column):string
+    public function alterColumn(string $tableAlias, ColumnSchema $column, ?string $position = null):string
     {
         if (property_exists($column, 'xDbType') && is_string($column->xDbType) && !empty($column->xDbType)) {
-            $converter = $this->columnToCode($tableAlias, $column, true, false, true, true);
+            $converter = $this->columnToCode($tableAlias, $column, true, false, true, true, $position);
             return sprintf(
                 ApiGenerator::isPostgres() ? self::ALTER_COLUMN_RAW_PGSQL : self::ALTER_COLUMN_RAW,
                 $tableAlias,
                 $column->name,
                 ColumnToCode::escapeQuotes($converter->getCode())
             );
         }
-        $converter = $this->columnToCode($tableAlias, $column, true);
+        $converter = $this->columnToCode($tableAlias, $column, true, false, false, false, $position);
         return sprintf(self::ALTER_COLUMN, $tableAlias, $column->name, $converter->getCode(true));
     }
 
     /**
      * @throws \yii\base\InvalidConfigException
      */
-    public function alterColumnType(string $tableAlias, ColumnSchema $column, bool $addUsing = false):string
-    {
+    public function alterColumnType(
+        string $tableAlias,
+        ColumnSchema $column,
+        bool $addUsing = false,
+        ?string $position = null
+    ):string {
         if (property_exists($column, 'xDbType') && is_string($column->xDbType) && !empty($column->xDbType)) {
-            $converter = $this->columnToCode($tableAlias, $column, false, false, true, true);
+            $converter = $this->columnToCode($tableAlias, $column, false, false, true, true, $position);
             return sprintf(
                 ApiGenerator::isPostgres() ? self::ALTER_COLUMN_RAW_PGSQL : self::ALTER_COLUMN_RAW,
                 $tableAlias,
                 $column->name,
                 rtrim(ltrim($converter->getAlterExpression($addUsing), "'"), "'")
             );
         }
-        $converter = $this->columnToCode($tableAlias, $column, false);
+        $converter = $this->columnToCode($tableAlias, $column, false, false, false, false, $position);
         return sprintf(self::ALTER_COLUMN, $tableAlias, $column->name, $converter->getAlterExpression($addUsing));
     }
 
     /**
      * This method is only used in Pgsql
      * @throws \yii\base\InvalidConfigException
      */
-    public function alterColumnTypeFromDb(string $tableAlias, ColumnSchema $column, bool $addUsing = false) :string
-    {
+    public function alterColumnTypeFromDb(
+        string $tableAlias,
+        ColumnSchema $column,
+        bool $addUsing = false,
+        ?string $position = null
+    ) :string {
         if (property_exists($column, 'xDbType') && is_string($column->xDbType) && !empty($column->xDbType)) {
-            $converter = $this->columnToCode($tableAlias, $column, true, false, true, true);
+            $converter = $this->columnToCode($tableAlias, $column, true, false, true, true, $position);
             return sprintf(
                 ApiGenerator::isPostgres() ? self::ALTER_COLUMN_RAW_PGSQL : self::ALTER_COLUMN_RAW,
                 $tableAlias,
                 $column->name,
                 rtrim(ltrim($converter->getAlterExpression($addUsing), "'"), "'")
             );
         }
-        $converter = $this->columnToCode($tableAlias, $column, true);
+        $converter = $this->columnToCode($tableAlias, $column, true, false, false, false, $position);
         return sprintf(self::ALTER_COLUMN, $tableAlias, $column->name, $converter->getAlterExpression($addUsing));
     }