Initial SQLite development (#1)

Reviewed-on: #1

src/Query/RemoveFields.php

@@ -0,0 +1,66 @@
+<?php declare(strict_types=1);
+
+namespace BitBadger\PDODocument\Query;
+
+use BitBadger\PDODocument\{Configuration, DocumentException, Field, Mode, Query};
+
+/**
+ * Queries to remove fields from documents
+ *
+ * _NOTE: When using these queries to build custom functions, be aware that different databases use significantly
+ *        different syntax. The `$parameters` passed to these functions should be run through `Parameters::fieldNames`
+ *        function to generate them appropriately for the database currently being targeted._
+ */
+class RemoveFields
+{
+    /**
+     * Create an UPDATE statement to remove fields from a JSON document
+     *
+     * @param string $tableName The name of the table in which documents should be manipulated
+     * @param array $parameters The parameter list for the query
+     * @param string $whereClause The body of the WHERE clause for the update
+     * @return string The UPDATE statement to remove fields from a JSON document
+     * @throws DocumentException If the database mode has not been set
+     */
+    public static function update(string $tableName, array $parameters, string $whereClause): string
+    {
+        switch (Configuration::$mode) {
+            case Mode::PgSQL:
+                return "UPDATE $tableName SET data = data - " . array_keys($parameters)[0] . " WHERE $whereClause";
+            case Mode::SQLite:
+                $paramNames = implode(', ', array_keys($parameters));
+                return "UPDATE $tableName SET data = json_remove(data, $paramNames) WHERE $whereClause";
+            default:
+                throw new DocumentException('Database mode not set; cannot generate field removal query');
+        }
+    }
+
+    /**
+     * Query to remove fields from a document by the document's ID
+     *
+     * @param string $tableName The name of the table in which the document should be manipulated
+     * @param array $parameters The parameter list for the query
+     * @return string The UPDATE statement to remove fields from a document by its ID
+     * @throws DocumentException If the database mode has not been set
+     */
+    public static function byId(string $tableName, array $parameters): string
+    {
+        return self::update($tableName, $parameters, Query::whereById());
+    }
+
+    /**
+     * Query to remove fields from documents via a comparison on JSON fields within the document
+     *
+     * @param string $tableName The name of the table in which documents should be manipulated
+     * @param array|Field[] $fields The field comparison to match
+     * @param array $parameters The parameter list for the query
+     * @param string $conjunction How to handle multiple conditions (optional; defaults to `AND`)
+     * @return string The UPDATE statement to remove fields from documents via field comparison
+     * @throws DocumentException If the database mode has not been set
+     */
+    public static function byFields(string $tableName, array $fields, array $parameters,
+                                    string $conjunction = 'AND'): string
+    {
+        return self::update($tableName, $parameters, Query::whereByFields($fields, $conjunction));
+    }
+}