StatementFactory helper class

sad_spirit\pg_builder\StatementFactory is, as its name implies, a class that deals with creating statements. It also takes care of properly configuring objects needed to create these statements based on PostgreSQL connection, if one is given.

It is recommended to use this class as an entrypoint to pg_builder features and to pass it as a dependency.

Public API

namespace sad_spirit\bg_builder;

use sad_spirit\pg_wrapper\Connection;

class StatementFactory
{
    // Constructor methods
    public function __construct(
        ?Parser $parser = null,
        ?StatementToStringWalker $builder = null,
        bool $PDOCompatible = false
    );
    public static function forConnection(Connection $connection) : self;
    public static function forPDO(\PDO $pdo) : self;

    // Getters
    public function getParser() : Parser;
    public function getBuilder() : StatementToStringWalker;

    // Converting SQL to AST and back
    public function createFromString(string $sql) : Statement;
    public function createFromAST(Statement $ast, bool $forcePDOPrepareCompatibility = false) : NativeStatement;

    // Factory methods for Statement subclasses
    public function delete(nodes\range\UpdateOrDeleteTarget|string $from) : Delete;
    public function insert(nodes\QualifiedName|nodes\range\InsertTarget|string $into) : Insert;
    public function merge(
        nodes\range\UpdateOrDeleteTarget|string $into,
        nodes\range\FromElement|string $using,
        nodes\ScalarExpression|string $on
    ) : Merge;
    public function select(
        string|iterable<nodes\TargetElement|string> $list,
        string|iterable<nodes\range\FromElement>|null $from = null
    ) : Select;
    public function update(
        nodes\range\UpdateOrDeleteTarget|string $table,
        string|iterable<nodes\SingleSetClause|nodes\MultipleSetClause|string> $set
    ) : Update;
    public function values(
        string|iterable<
            nodes\expressions\RowExpression|
            string|
            iterable<nodes\ScalarExpression|nodes\SetToDefault|string>
        > $rows
    ) : Values;
}

Constructor methods and getters

Constructor arguments

__construct() accepts an instance of Parser and an implementation of StatementToStringWalker, the latter is implemented by SqlBuilderWalker. If these are not provided, default instances will be created.

$PDOCompatible flag triggers generating queries targeting PDO rather than native pgsql extension. Specifically,

• Named parameters will not be replaced by positional ones;

• Dollar-quoting will not be used;

• If the query has parameter placeholders, question marks used in operators will be doubled so that \PDO::prepare() will not treat them as placeholders as well.

forConnection() and forPDO() “named constructors”

These methods create an instance of StatementFactory based on properties of a native connection or a PDO one, respectively. The latter also enables compatibility to PDO.

The following settings will be configured:

• Lexer instance used by Parser will follow server’s standard_conforming_strings setting.

• If client_encoding is anything but UTF-8 then SqlBuilderWalker will have escape_unicode enabled.

• Additionally, Parser will reuse the metadata cache of Connection for caching ASTs, if available.

getParser() and getBuilder()

These are self-explanatory, returning properties set in the constructor.

Conversion methods

These use Parser and SqlBuilderWalker to convert query from SQL string to AST and back:

createFromString()

Creates an AST representing a complete statement from SQL string. Returns an instance of Statement subclass, already having an instance of Parser added to it (so it can accept strings as query parts).

createFromAST()

Creates an object containing SQL statement string and parameter mappings from AST. The returned NativeStatement object can be cached to prevent re-running expensive parsing and building operations.

If $forcePDOPrepareCompatibility flag is true, then generated SQL will be compatible with \PDO::prepare() even if $PDOCompatible flag was not passed to constructor or if the query does not contain parameter placeholders, see the relevant issue.

Creating Statements

The following methods are wrappers around Statement subclasses’ constructors. Their added value is

• They accept strings in addition to Node implementations,

• The Statements they create will have Parser already added.

delete()

Creates a DELETE statement object.

insert()

Creates an INSERT statement object.

merge()

Creates a MERGE statement object.

select()

Creates a SELECT statement object. The $list and $from can be strings or arrays of strings or proper Node implementations.

update()

Creates an UPDATE statement object. The $set argument can be an array of strings or proper Node implementations.

values()

Create a VALUES statement object (this can be a separate statement in Postgres). If $rows argument is an array or iterable, its first dimension represents rows and the second one represents columns.