Make the autoupdate logic much more generic (#48)

* Code cleanup

* Fix lint errors

Author: Quentin Presley

lib/migration.js

@@ -123,129 +123,19 @@ module.exports = function(IBMDB) {
     return operations;
   };
 
-  IBMDB.prototype.addIndexes = function(model, actualIndexes) {
-    var ai = {};
-    var self = this;
-    var m = this.getModelDefinition(model);
-    var indexes = m.settings.indexes || {};
-    var indexNames = Object.keys(indexes).filter(function(name) {
-      return !!m.settings.indexes[name];
-    });
+  IBMDB.prototype.dropIndexes = function(model, actualIndexes) {
     var operations = [];
-    var propNames = Object.keys(m.properties).filter(function(name) {
-      return !!m.properties[name];
-    });
-    var sql = [];
-    var type = '';
 
+    // If there are indexes for this table then we need to drop them.
+    // Generate the statements here to drop all known indexes.
     if (actualIndexes) {
       actualIndexes.forEach(function(i) {
-        var name = i.INDNAME;
-        if (!ai[name]) {
-          ai[name] = {
-            info: i,
-            columns: [],
-          };
-        }
-
-        i.COLNAMES.split(/\+\s*/).forEach(function(columnName, j) {
-          // This is a bit of a dirty way to get around this but DB2 returns
-          // column names as a string started with and separated by a '+'.
-          // The code below will strip out the initial '+' then store the
-          // actual column names.
-          if (j > 0)
-            ai[name].columns[j - 1] = columnName;
-        });
+        var stmt = 'DROP INDEX ' + i.INDNAME;
+        operations.push(stmt);
       });
     }
-    var aiNames = Object.keys(ai);
-    // remove indexes
-    aiNames.forEach(function(indexName) {
-      if (ai[indexName].info.UNIQUERULE === 'P' || // indexName === 'PRIMARY' ||
-        (m.properties[indexName] && self.id(model, indexName))) return;
 
-      if (indexNames.indexOf(indexName) === -1 && !m.properties[indexName] ||
-      m.properties[indexName] && !m.properties[indexName].index) {
-        if (ai[indexName].info.UNIQUERULE === 'P') {
-          operations.push('DROP PRIMARY KEY');
-        } else if (ai[indexName].info.UNIQUERULE === 'U') {
-          operations.push('DROP UNIQUE ' + indexName);
-        }
-      } else {
-        // first: check single (only type and kind)
-        if (m.properties[indexName] && !m.properties[indexName].index) {
-          // TODO
-          return;
-        }
-        // second: check multiple indexes
-        var orderMatched = true;
-        if (indexNames.indexOf(indexName) !== -1) {
-          m.settings.indexes[indexName].columns.split(/,\s*/).forEach(
-          function(columnName, i) {
-            if (ai[indexName].columns[i] !== columnName)
-              orderMatched = false;
-          });
-        }
-
-        if (!orderMatched) {
-          if (ai[indexName].info.UNIQUERULE === 'P') {
-            operations.push('DROP PRIMARY KEY');
-          } else if (ai[indexName].info.UNIQUERULE === 'U') {
-            operations.push('DROP UNIQUE ' + indexName);
-          }
-
-          delete ai[indexName];
-        }
-      }
-    });
-
-    if (operations.length) {
-      // Add the ALTER TABLE statement to the list of tasks to perform later.
-      sql.push('ALTER TABLE ' + self.schema + '.' +
-              self.tableEscaped(model) + ' ' + operations.join(' ') + ';');
-    }
-
-    // add single-column indexes
-    propNames.forEach(function(propName) {
-      var i = m.properties[propName].index;
-      if (!i) {
-        return;
-      }
-      var found = ai[propName] && ai[propName].info;
-      if (!found) {
-        var pName = propName;
-        type = '';
-        if (i.type) {
-          type = i.type;
-        }
-        sql.push('CREATE ' + type + ' INDEX ' + pName + ' ON ' +
-        self.schema + '.' + self.tableEscaped(model) +
-        '(\"' + pName + '\") ');
-      }
-    });
-
-    // add multi-column indexes
-    indexNames.forEach(function(indexName) {
-      var i = m.settings.indexes[indexName];
-      var found = ai[indexName] && ai[indexName].info;
-      if (!found) {
-        var iName = indexName;
-        var type = '';
-        if (i.type) {
-          type = i.type;
-        }
-        var stmt = 'CREATE ' + type + 'INDEX ' + iName + ' ON ' +
-        self.schema + '.' + self.tableEscaped(model) + '(';
-
-        var splitNames = i.columns.split(/,\s*/);
-        var colNames = splitNames.join('\",\"');
-
-        stmt += '\"' + colNames + '\")';
-
-        sql.push(stmt);
-      }
-    });
-    return sql;
+    return operations;
   };
 
   IBMDB.prototype.alterTable = function(model, actualFields, actualIndexes,
@@ -256,6 +146,12 @@ module.exports = function(IBMDB) {
     var sql = [];
     var tasks = [];
 
+    // Create the statements to drop all existing indexes before we start
+    // altering the table.
+    sql = sql.concat(self.dropIndexes(model, actualIndexes));
+
+    // Add/Modify and drop column statements for ALTER TABLE are generated
+    // prior to re-building the indexes as defined in the model.
     var operations = self.getAddModifyColumns(model, actualFields);
     operations = operations.concat(self.getDropColumns(model, actualFields));
 
@@ -264,7 +160,11 @@ module.exports = function(IBMDB) {
       sql.push('ALTER TABLE ' + self.schema + '.' +
               self.tableEscaped(model) + ' ' + operations.join(' ') + ';');
     }
-    sql = sql.concat(self.addIndexes(model, actualIndexes));
+
+    // Now that the column altering statments have been added we can add in the
+    // indexes again.
+    // ------------------------------------------------------------------------
+    sql = sql.concat(self.buildIndexes(model));
 
     sql.forEach(function(i) {
       tasks.push(function(cb) {