sqlite-plugin-red/utils/sqliteServer.js

Adding a tab to show and edit the structure of a sqlite database. Needs node-red-node-sqlite.

const Database = require('better-sqlite3')

const getStructure = (path) => {
  const db = new Database(path)
  const tables = db.prepare('SELECT name, sql FROM sqlite_master WHERE type=? AND name NOT LIKE ?')
  const structure = []
  for (const table of tables.iterate('table', 'sqlite_%')) {
    const tableObject = { name: table.name }
    // autoincrement info can only received by table sql. We could also retrieve all neccessary table infos from here,
    // but it must be filtered from a string... we only do this here as AUTONINCREMENT can only be set once (and then there is only one primary key)
    if (table.sql.includes('PRIMARY KEY') && table.sql.includes('AUTOINCREMENT')) {
      tableObject.autoincrement = table.sql.split('PRIMARY KEY(')[1].split('"')[1]
    }
    structure.push(tableObject)
  }
  // ...therefore we get the column data from pragma table_info
  structure.forEach((table, index) => {
    const columns = db.prepare('PRAGMA table_info( "' + table.name + '" );').all()
    // and change number to bool for checkbox using later
    columns.forEach(c => {
      if (c.notnull === 0) c.notnull = false
      else c.notnull = true
      if (c.pk === 0) c.pk = false
      else c.notnull = true
      c.ai = false
      c.unique = false
    })

    // ... and add the autoincrement there
    if (table.autoincrement) {
      const autoIncrIndex = columns.findIndex(c => c.name === table.autoincrement)
      if (autoIncrIndex !== -1) {
        columns[autoIncrIndex].ai = true
        delete table.autoincrement
      }
    }
    // ... as well as if the column is unique
    const uniqueFields = db.prepare('SELECT DISTINCT m.name as table_name, ii.name as column_name FROM sqlite_master AS m, pragma_index_list(m.name) AS il, pragma_index_info(il.name) AS ii WHERE m.type=? AND il.[unique] = 1;').bind('table').all()
    const uniqueFieldsInThisTable = uniqueFields.filter(f => f.table_name === table.name)
    uniqueFieldsInThisTable.forEach(uField => {
      const uFieldIndex = columns.findIndex(c => c.name === uField.column_name)
      if (uFieldIndex > -1) columns[uFieldIndex].unique = true
    })
    structure[index].columns = columns
  })
  db.close()
  return structure
}

const runSql = (path, sql, command) => {
  const db = new Database(path)
  const statement = db.prepare(sql)
  let result
  try {
    if (command === 'run') {
      result = statement.run()
    } else if (command === 'getAll') {
      result = statement.all()
      if (typeof result === 'undefined') result = {}
    } else if (command === 'get') {
      result = statement.get()
      if (typeof result === 'undefined') result = {}
    } else {
      throw new Error('No command stated!')
    }
    return result
  } catch(e) {
    throw new Error(e)
  }
}

const createTableWithNewProp = (path, fields, fieldsSql, backupName) => {
  const tempBackup = backupName + '_temp_' + Date.now() + Math.floor(Math.random() * Number.MAX_SAFE_INTEGER)
  createCopyDb(path, fields, fieldsSql, backupName, tempBackup)
  commitCopyDb(path, backupName, tempBackup)
}

const createCopyDb = (path, fields, fieldsSql, tableName, backupName) => {
  const db = new Database(path)
  if (!tableName || !backupName) throw new Error('Missing table name!')
  try {
    // Steps for altering column props as stated in https://www.sqlite.org/lang_altertable.html
    // Create new table
    db.prepare(`CREATE TABLE "${backupName}" ${fieldsSql}`).run()
    // Copy data
    db.prepare(`INSERT INTO "${backupName}" (${fields}) SELECT ${fields} FROM "${tableName}"`).run()
    return 'db copy'
  } catch (e) {
    db.prepare('DROP TABLE IF EXISTS "' + backupName + '"').run()
    throw new Error(e)
  }
}

const commitCopyDb = (path, tableName, backupName) => {
  // to change a column property we have to go through the following steps... an alter table column will propably never be implemented (expect name changing)
  const db = new Database(path)
  if (!tableName || !backupName) throw new Error('Missing table name!')
  try {
    // Drop old table (first check if data was copied!)
    const getFirstLineOrg = db.prepare('SELECT * FROM "' + tableName + '"').get()
    const getFirstLineCopy = db.prepare('SELECT * FROM "' + backupName + '"').get()
    if (getFirstLineOrg && !getFirstLineCopy) {
      throw new Error('Something went wrong! Database copy is missing data -> Reset all db changes.')
    } else {
      db.prepare('DROP TABLE "' + tableName + '"').run()
      // Rename new into old
      db.prepare(`ALTER TABLE "${backupName}" RENAME TO "${tableName}";`).run()
      db.close()
      return 'Table changed'
    }
  } catch (e) {
    db.prepare('DROP TABLE IF EXISTS "' + backupName + '"').run()
    throw new Error(e)
  }
}

module.exports = {
  getStructure,
  runSql,
  createTableWithNewProp,
  createCopyDb,
  commitCopyDb
}