Added destroyColumn migration step

CHANGELOG-Unreleased.md

@@ -7,6 +7,7 @@
 ### New features
 
 - Added `Database#experimentalIsVerbose` option
+- Added destroyColumn migration step.
 
 ### Fixes
 

src/RawRecord/index.d.ts

@@ -1,7 +1,6 @@
 import type { ColumnName, ColumnSchema, TableSchema } from '../Schema'
 import type { RecordId, SyncStatus } from '../Model'
 
-
 // Raw object representing a model record, coming from an untrusted source
 // (disk, sync, user data). Before it can be used to create a Model instance
 // it must be sanitized (with `sanitizedRaw`) into a RawRecord
@@ -15,7 +14,7 @@ type _RawRecord = {
 }
 
 // Raw object representing a model record. A RawRecord is guaranteed by the type system
-// to be safe to use (sanitied with `sanitizedRaw`):
+// to be safe to use (sanitized with `sanitizedRaw`):
 // - it has exactly the fields described by TableSchema (+ standard fields)
 // - every field is exactly the type described by ColumnSchema (string, number, or boolean)
 // - … and the same optionality (will not be null unless isOptional: true)

src/Schema/migrations/index.d.ts

@@ -1,5 +1,12 @@
 import type { $RE, $Exact } from '../../types'
-import type { ColumnSchema, TableName, TableSchema, TableSchemaSpec, SchemaVersion } from '../index'
+import type {
+  ColumnName,
+  ColumnSchema,
+  TableName,
+  TableSchema,
+  TableSchemaSpec,
+  SchemaVersion,
+} from '../index'
 
 export type CreateTableMigrationStep = $RE<{
   type: 'create_table'
@@ -13,12 +20,22 @@ export type AddColumnsMigrationStep = $RE<{
   unsafeSql?: (_: string) => string
 }>
 
+export type DestroyColumnMigrationStep = $RE<{
+  type: 'destroy_column'
+  table: TableName<any>
+  column: ColumnName
+}>
+
 export type SqlMigrationStep = $RE<{
   type: 'sql'
   sql: string
 }>
 
-export type MigrationStep = CreateTableMigrationStep | AddColumnsMigrationStep | SqlMigrationStep
+export type MigrationStep =
+  | CreateTableMigrationStep
+  | AddColumnsMigrationStep
+  | DestroyColumnMigrationStep
+  | SqlMigrationStep
 
 type Migration = $RE<{
   toVersion: SchemaVersion
@@ -50,4 +67,12 @@ export function addColumns({
   unsafeSql?: (_: string) => string
 }>): AddColumnsMigrationStep
 
+export function destroyColumn({
+  table,
+  column,
+}: $Exact<{
+  table: TableName<any>
+  column: ColumnName
+}>): DestroyColumnMigrationStep
+
 export function unsafeExecuteSql(sql: string): SqlMigrationStep

src/Schema/migrations/index.js

@@ -6,7 +6,14 @@ import invariant from '../../utils/common/invariant'
 import isObj from '../../utils/fp/isObj'
 
 import type { $RE } from '../../types'
-import type { ColumnSchema, TableName, TableSchema, TableSchemaSpec, SchemaVersion } from '../index'
+import type {
+  ColumnName,
+  ColumnSchema,
+  TableName,
+  TableSchema,
+  TableSchemaSpec,
+  SchemaVersion,
+} from '../index'
 import { tableSchema, validateColumnSchema } from '../index'
 
 export type CreateTableMigrationStep = $RE<{
@@ -21,12 +28,22 @@ export type AddColumnsMigrationStep = $RE<{
   unsafeSql?: (string) => string,
 }>
 
+export type DestroyColumnMigrationStep = $RE<{
+  type: 'destroy_column',
+  table: TableName<any>,
+  column: ColumnName,
+}>
+
 export type SqlMigrationStep = $RE<{
   type: 'sql',
   sql: string,
 }>
 
-export type MigrationStep = CreateTableMigrationStep | AddColumnsMigrationStep | SqlMigrationStep
+export type MigrationStep =
+  | CreateTableMigrationStep
+  | AddColumnsMigrationStep
+  | DestroyColumnMigrationStep
+  | SqlMigrationStep
 
 type Migration = $RE<{
   toVersion: SchemaVersion,
@@ -159,6 +176,21 @@ export function addColumns({
   return { type: 'add_columns', table, columns, unsafeSql }
 }
 
+export function destroyColumn({
+  table,
+  column,
+}: $Exact<{
+  table: TableName<any>,
+  column: ColumnName,
+}>): DestroyColumnMigrationStep {
+  if (process.env.NODE_ENV !== 'production') {
+    invariant(table, `Missing table name in destroyColumn()`)
+    invariant(column, `Missing column in destroyColumn()`)
+  }
+
+  return { type: 'destroy_column', table, column }
+}
+
 export function unsafeExecuteSql(sql: string): SqlMigrationStep {
   if (process.env.NODE_ENV !== 'production') {
     invariant(typeof sql === 'string', `SQL passed to unsafeExecuteSql is not a string`)
@@ -176,7 +208,6 @@ renameTable({ from: 'old_table_name', to: 'new_table_name' })
 
 // column operations
 renameColumn({ table: 'table_name', from: 'old_column_name', to: 'new_column_name' })
-destroyColumn({ table: 'table_name', column: 'column_name' })
 
 // indexing
 addColumnIndex({ table: 'table_name', column: 'column_name' })

src/Schema/migrations/test.js

@@ -1,4 +1,4 @@
-import { createTable, addColumns, schemaMigrations } from './index'
+import { createTable, addColumns, destroyColumn, schemaMigrations } from './index'
 import { stepsForMigration } from './stepsForMigration'
 
 describe('schemaMigrations()', () => {
@@ -30,7 +30,19 @@ describe('schemaMigrations()', () => {
   it('returns a complex schema migrations spec', () => {
     const migrations = schemaMigrations({
       migrations: [
-        { toVersion: 4, steps: [] },
+        {
+          toVersion: 4,
+          steps: [
+            addColumns({
+              table: 'comments',
+              columns: [{ name: 'text', type: 'string' }],
+            }),
+            destroyColumn({
+              table: 'comments',
+              column: 'body',
+            }),
+          ],
+        },
         {
           toVersion: 3,
           steps: [
@@ -103,7 +115,21 @@ describe('schemaMigrations()', () => {
             },
           ],
         },
-        { toVersion: 4, steps: [] },
+        {
+          toVersion: 4,
+          steps: [
+            {
+              type: 'add_columns',
+              table: 'comments',
+              columns: [{ name: 'text', type: 'string' }],
+            },
+            {
+              type: 'destroy_column',
+              table: 'comments',
+              column: 'body',
+            },
+          ],
+        },
       ],
     })
   })
@@ -181,6 +207,10 @@ describe('migration step functions', () => {
       'type',
     )
   })
+  it('throws if destroyColumn() is malformed', () => {
+    expect(() => destroyColumn({ column: 'foo' })).toThrow('table')
+    expect(() => destroyColumn({ table: 'foo' })).toThrow('column')
+  })
 })
 
 describe('stepsForMigration', () => {

src/adapters/lokijs/worker/DatabaseDriver.js

@@ -15,6 +15,7 @@ import type {
   SchemaMigrations,
   CreateTableMigrationStep,
   AddColumnsMigrationStep,
+  DestroyColumnMigrationStep,
   MigrationStep,
 } from '../../../Schema/migrations'
 import type { SerializedQuery } from '../../../Query'
@@ -390,6 +391,8 @@ export default class DatabaseDriver {
         this._executeCreateTableMigration(step)
       } else if (step.type === 'add_columns') {
         this._executeAddColumnsMigration(step)
+      } else if (step.type === 'destroy_column') {
+        this._executeDestroyColumnMigration(step)
       } else if (step.type === 'sql') {
         // ignore
       } else {
@@ -425,6 +428,15 @@ export default class DatabaseDriver {
     })
   }
 
+  _executeDestroyColumnMigration({ table, column }: DestroyColumnMigrationStep): void {
+    const collection = this.loki.getCollection(table)
+
+    // update ALL records in the collection, removing a field
+    collection.findAndUpdate({}, (record) => {
+      delete record[column]
+    })
+  }
+
   // Maps records to their IDs if the record is already cached on JS side
   _compactQueryResults(records: DirtyRaw[], table: TableName<any>): CachedQueryResult {
     const cache = this.getCache(table)

src/adapters/sqlite/encodeSchema/index.js

@@ -2,7 +2,11 @@
 
 import type { TableSchema, AppSchema, ColumnSchema, TableName } from '../../../Schema'
 import { nullValue } from '../../../RawRecord'
-import type { MigrationStep, AddColumnsMigrationStep } from '../../../Schema/migrations'
+import type {
+  MigrationStep,
+  AddColumnsMigrationStep,
+  DestroyColumnMigrationStep,
+} from '../../../Schema/migrations'
 import type { SQL } from '../index'
 
 import encodeValue from '../encodeValue'
@@ -85,13 +89,36 @@ const encodeAddColumnsMigrationStep: (AddColumnsMigrationStep) => SQL = ({
     })
     .join('')
 
-export const encodeMigrationSteps: (MigrationStep[]) => SQL = (steps) =>
+const encodeDestroyColumnMigrationStep: (DestroyColumnMigrationStep, TableSchema) => SQL = (
+  { table, column },
+  tableSchema,
+) => {
+  const newTempTable = { ...tableSchema, name: `${table}Temp` }
+  const newColumns = [
+    ...standardColumns,
+    ...Object.keys(tableSchema.columns)
+      .filter((c) => c !== column)
+      .map((c) => `"${c}`),
+  ]
+  return `
+      ${encodeTable(newTempTable)}
+      INSERT INTO ${table}Temp(${newColumns.join(',')}) SELECT ${newColumns.join(
+    ',',
+  )} FROM ${table};
+      DROP TABLE ${table};
+      ALTER TABLE ${table}Temp RENAME TO ${table};
+    `
+}
+
+export const encodeMigrationSteps: (MigrationStep[], AppSchema) => SQL = (steps, schema) =>
   steps
     .map((step) => {
       if (step.type === 'create_table') {
         return encodeTable(step.schema)
       } else if (step.type === 'add_columns') {
         return encodeAddColumnsMigrationStep(step)
+      } else if (step.type === 'destroy_column') {
+        return encodeDestroyColumnMigrationStep(step, schema.tables[step.table])
       } else if (step.type === 'sql') {
         return step.sql
       }

src/adapters/sqlite/index.js

@@ -169,7 +169,7 @@ export default class SQLiteAdapter implements DatabaseAdapter {
         'setUpWithMigrations',
         [
           this.dbName,
-          require('./encodeSchema').encodeMigrationSteps(migrationSteps),
+          require('./encodeSchema').encodeMigrationSteps(migrationSteps, this.schema),
           databaseVersion,
           this.schema.version,
         ],