From eb9d2bcd649b6dba7e764ae5f34a61c8b0c51d9c Mon Sep 17 00:00:00 2001
From: saxenabhishek <as7122000@gmail.com>
Date: Thu, 15 Jul 2021 01:21:31 +0530
Subject: [PATCH] feat: Query builder

---
 frappe/__init__.py               |  4 +++
 frappe/query_builder/__init__.py |  1 +
 frappe/query_builder/qb.py       | 53 ++++++++++++++++++++++++++++++++
 requirements.txt                 |  1 +
 4 files changed, 59 insertions(+)
 create mode 100644 frappe/query_builder/__init__.py
 create mode 100644 frappe/query_builder/qb.py

diff --git a/frappe/__init__.py b/frappe/__init__.py
index 1c978945c7..39e21efb9e 100644
--- a/frappe/__init__.py
+++ b/frappe/__init__.py
@@ -28,6 +28,8 @@ from .exceptions import *
 from .utils.jinja import (get_jenv, get_template, render_template, get_email_from_template, get_jloader)
 from .utils.lazy_loader import lazy_import
 
+from frappe.query_builder import query_builder
+
 # Lazy imports
 faker = lazy_import('faker')
 
@@ -118,6 +120,7 @@ def set_user_lang(user, user_language=None):
 
 # local-globals
 db = local("db")
+qb = local("qb")
 conf = local("conf")
 form = form_dict = local("form_dict")
 request = local("request")
@@ -202,6 +205,7 @@ def init(site, sites_path=None, new_site=False):
 	local.form_dict = _dict()
 	local.session = _dict()
 	local.dev_server = _dev_server
+	local.qb = query_builder(local.conf.db_type)
 
 	setup_module_map()
 
diff --git a/frappe/query_builder/__init__.py b/frappe/query_builder/__init__.py
new file mode 100644
index 0000000000..da1748beec
--- /dev/null
+++ b/frappe/query_builder/__init__.py
@@ -0,0 +1 @@
+from frappe.query_builder.qb import qb as query_builder
diff --git a/frappe/query_builder/qb.py b/frappe/query_builder/qb.py
new file mode 100644
index 0000000000..6fa54661e8
--- /dev/null
+++ b/frappe/query_builder/qb.py
@@ -0,0 +1,53 @@
+from pypika import MySQLQuery, Order, PostgreSQLQuery
+from pypika import functions as fn
+from pypika import terms
+from pypika.queries import Schema, Table
+
+def qb(db_type):
+	if not db_type:
+		db_type = "mariadb"
+	selecter = {"mariadb": MariaDB, "postgres": Postgres}
+	return selecter[db_type]
+
+class common:
+	fn = fn
+	terms = terms
+	desc = Order.desc
+	Schema = Schema
+
+class MariaDB(MySQLQuery,common):
+	Field = terms.Field
+
+	def __init__(self) -> None:
+		super().__init__()
+	
+	@classmethod
+	def from_(cls, class_name, *args, **kwargs):
+		if isinstance(class_name,str):
+			class_name = "tab"+class_name
+		return super().from_(class_name, *args, **kwargs)
+
+class Postgres(PostgreSQLQuery,common):
+	postgres_field = {"table_name": "relname", "table_rows": "n_tup_ins"}
+	information_schema_translation = {"tables": "pg_stat_all_tables"}
+
+	def __init__(self) -> None:
+		super().__init__()
+
+	@classmethod
+	def Field(cls, fieldName, *args, **kwargs):
+		if fieldName in cls.postgres_field:
+			fieldName = cls.postgres_field[fieldName]
+		return terms.Field(fieldName, *args, **kwargs)
+
+	@classmethod
+	def from_(cls, class_name, *args, **kwargs):
+		if isinstance(class_name, Table):
+			if class_name._schema:
+				if class_name._schema._name == "information_schema":
+					class_name = cls.information_schema_translation[class_name._table_name]
+
+		elif isinstance(class_name, str):
+			class_name = "tab" + class_name
+
+		return super().from_(class_name, *args, **kwargs)
\ No newline at end of file
diff --git a/requirements.txt b/requirements.txt
index 0791f01b27..51327953d5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -49,6 +49,7 @@ pyngrok~=5.0.5
 pyOpenSSL~=20.0.1
 pyotp~=2.6.0
 PyPDF2~=1.26.0
+PyPika~=0.48.6
 pypng~=0.0.20
 PyQRCode~=1.2.1
 python-dateutil~=2.8.1