knex/lib/dialects/postgres/schema/compiler.js

// PostgreSQL Schema Compiler
// -------

const inherits = require('inherits');
const SchemaCompiler = require('../../../schema/compiler');

function SchemaCompiler_PG() {
  SchemaCompiler.apply(this, arguments);
}
inherits(SchemaCompiler_PG, SchemaCompiler);

// Check whether the current table
SchemaCompiler_PG.prototype.hasTable = function (tableName) {
  let sql = 'select * from information_schema.tables where table_name = ?';
  const bindings = [tableName];

  if (this.schema) {
    sql += ' and table_schema = ?';
    bindings.push(this.schema);
  } else {
    sql += ' and table_schema = current_schema()';
  }

  this.pushQuery({
    sql,
    bindings,
    output(resp) {
      return resp.rows.length > 0;
    },
  });
};

// Compile the query to determine if a column exists in a table.
SchemaCompiler_PG.prototype.hasColumn = function (tableName, columnName) {
  let sql =
    'select * from information_schema.columns where table_name = ? and column_name = ?';
  const bindings = [tableName, columnName];

  if (this.schema) {
    sql += ' and table_schema = ?';
    bindings.push(this.schema);
  } else {
    sql += ' and table_schema = current_schema()';
  }

  this.pushQuery({
    sql,
    bindings,
    output(resp) {
      return resp.rows.length > 0;
    },
  });
};

SchemaCompiler_PG.prototype.qualifiedTableName = function (tableName) {
  const name = this.schema ? `${this.schema}.${tableName}` : tableName;
  return this.formatter.wrap(name);
};

// Compile a rename table command.
SchemaCompiler_PG.prototype.renameTable = function (from, to) {
  this.pushQuery(
    `alter table ${this.qualifiedTableName(
      from
    )} rename to ${this.formatter.wrap(to)}`
  );
};

SchemaCompiler_PG.prototype.createSchema = function (schemaName) {
  this.pushQuery(`create schema ${this.formatter.wrap(schemaName)}`);
};

SchemaCompiler_PG.prototype.createSchemaIfNotExists = function (schemaName) {
  this.pushQuery(
    `create schema if not exists ${this.formatter.wrap(schemaName)}`
  );
};

SchemaCompiler_PG.prototype.dropSchema = function (schemaName) {
  this.pushQuery(`drop schema ${this.formatter.wrap(schemaName)}`);
};

SchemaCompiler_PG.prototype.dropSchemaIfExists = function (schemaName) {
  this.pushQuery(`drop schema if exists ${this.formatter.wrap(schemaName)}`);
};

SchemaCompiler_PG.prototype.dropExtension = function (extensionName) {
  this.pushQuery(`drop extension ${this.formatter.wrap(extensionName)}`);
};

SchemaCompiler_PG.prototype.dropExtensionIfExists = function (extensionName) {
  this.pushQuery(
    `drop extension if exists ${this.formatter.wrap(extensionName)}`
  );
};

SchemaCompiler_PG.prototype.createExtension = function (extensionName) {
  this.pushQuery(`create extension ${this.formatter.wrap(extensionName)}`);
};

SchemaCompiler_PG.prototype.createExtensionIfNotExists = function (
  extensionName
) {
  this.pushQuery(
    `create extension if not exists ${this.formatter.wrap(extensionName)}`
  );
};

module.exports = SchemaCompiler_PG;