fix: allow implicit conversion of column types

Done using the USING clause of ALTER COLUMN, like so:

ALTER TABLE schema_name.table_name ALTER column_name SET DATA TYPE text
USING column_name::text;

It's possible to allow users to specify their own conversion expression,
but decided to omit it for now. We'll revisit that when the need arises.

Author: soedirgo

src/api/columns.ts

@@ -171,10 +171,11 @@ const alterColumnSqlize = ({
     typeof name === 'undefined' || name === oldName
       ? ''
       : `ALTER TABLE "${schema}"."${table}" RENAME COLUMN "${oldName}" TO "${name}";`
+  // We use USING to allow implicit conversion of incompatible types (e.g. int4 -> text).
   const typeSql =
     type === undefined
       ? ''
-      : `ALTER TABLE "${schema}"."${table}" ALTER COLUMN "${oldName}" SET DATA TYPE "${type}";`
+      : `ALTER TABLE "${schema}"."${table}" ALTER COLUMN "${oldName}" SET DATA TYPE "${type}" USING "${oldName}"::"${type}";`
   let defaultValueSql = ''
   if (drop_default) {
     defaultValueSql = `ALTER TABLE "${schema}"."${table}" ALTER COLUMN "${oldName}" DROP DEFAULT;`

test/integration/index.spec.js

@@ -355,6 +355,23 @@ describe('/tables', async () => {
     await axios.delete(`${URL}/columns/${newTable.id}.1`)
     await axios.delete(`${URL}/tables/${newTable.id}`)
   })
+  it('PATCH /columns "incompatible" types', async () => {
+    const { data: newTable } = await axios.post(`${URL}/tables`, { name: 'foo' })
+    await axios.post(`${URL}/columns`, {
+      table_id: newTable.id,
+      name: 'bar',
+      type: 'text',
+    })
+
+    const { data: updatedColumn } = await axios.patch(`${URL}/columns/${newTable.id}.1`, {
+      type: 'int4',
+    })
+
+    assert.strictEqual(updatedColumn.format, 'int4')
+
+    await axios.delete(`${URL}/columns/${newTable.id}.1`)
+    await axios.delete(`${URL}/tables/${newTable.id}`)
+  })
   it('DELETE /columns', async () => {
     const { data: newTable } = await axios.post(`${URL}/tables`, { name: 'foo bar' })
     await axios.post(`${URL}/columns`, { table_id: newTable.id, name: 'foo bar', type: 'int2' })