Add basic migrations

datalite/__init__.py

@@ -1,3 +1,3 @@
-__all__ = ['commons', 'datalite_decorator', 'fetch', 'datalite']
+__all__ = ['commons', 'datalite_decorator', 'fetch', 'migrations', 'datalite']
 
 from .datalite_decorator import datalite

datalite/commons.py

@@ -1,4 +1,6 @@
-from typing import Any, Optional, Dict
+from dataclasses import Field
+from typing import Any, Optional, Dict, List
+import sqlite3 as sql
 
 
 def _convert_type(type_: Optional[type], type_overload: Dict[Optional[type], str]) -> str:
@@ -33,4 +35,52 @@ def _convert_sql_format(value: Any) -> str:
     elif isinstance(value, bytes):
         return '"' + str(value).replace("b'", "")[:-1] + '"'
     else:
-        return str(value)
+        return str(value)
+
+
+def _get_table_cols(cur: sql.Cursor, table_name: str) -> List[str]:
+    """
+    Get the column data of a table.
+
+    :param cur: Cursor in database.
+    :param table_name: Name of the table.
+    :return: the information about columns.
+    """
+    cur.execute(f"PRAGMA table_info({table_name});")
+    return [row_info[1] for row_info in cur.fetchall()][1:]
+
+
+def _get_default(default_object: object, type_overload: Dict[Optional[type], str]) -> str:
+    """
+    Check if the field's default object is filled,
+    if filled return the string to be put in the,
+    database.
+    :param default_object: The default field of the field.
+    :param type_overload: Type overload table.
+    :return: The string to be put on the table statement,
+    empty string if no string is necessary.
+    """
+    if type(default_object) in type_overload:
+        return f' DEFAULT {_convert_sql_format(default_object)}'
+    return ""
+
+
+def _create_table(class_: type, cursor: sql.Cursor, type_overload: Dict[Optional[type], str]) -> None:
+    """
+    Create the table for a specific dataclass given
+    :param class_: A dataclass.
+    :param cursor: Current cursor instance.
+    :param type_overload: Overload the Python -> SQLDatatype table
+    with a custom table, this is that custom table.
+    :return: None.
+    """
+    fields: List[Field] = [class_.__dataclass_fields__[key] for
+                           key in class_.__dataclass_fields__.keys()]
+    fields.sort(key=lambda field: field.name)  # Since dictionaries *may* be unsorted.
+    sql_fields = ', '.join(f"{field.name} {_convert_type(field.type, type_overload)}"
+                           f"{_get_default(field.default, type_overload)}" for field in fields)
+    sql_fields = "obj_id INTEGER PRIMARY KEY AUTOINCREMENT, " + sql_fields
+    cursor.execute(f"CREATE TABLE IF NOT EXISTS {class_.__name__.lower()} ({sql_fields});")
+
+type_table: Dict[Optional[type], str] = {None: "NULL", int: "INTEGER", float: "REAL",
+                                                 str: "TEXT", bytes: "BLOB"}

datalite/datalite_decorator.py

@@ -6,40 +6,7 @@ a class bound to a sqlite3 database.
 from typing import Dict, Optional, List, Callable
 from dataclasses import Field, asdict
 import sqlite3 as sql
-from .commons import _convert_sql_format, _convert_type
-
-
-def _get_default(default_object: object, type_overload: Dict[Optional[type], str]) -> str:
-    """
-    Check if the field's default object is filled,
-    if filled return the string to be put in the,
-    database.
-    :param default_object: The default field of the field.
-    :param type_overload: Type overload table.
-    :return: The string to be put on the table statement,
-    empty string if no string is necessary.
-    """
-    if type(default_object) in type_overload:
-        return f' DEFAULT {_convert_sql_format(default_object)}'
-    return ""
-
-
-def _create_table(class_: type, cursor: sql.Cursor, type_overload: Dict[Optional[type], str]) -> None:
-    """
-    Create the table for a specific dataclass given
-    :param class_: A dataclass.
-    :param cursor: Current cursor instance.
-    :param type_overload: Overload the Python -> SQLDatatype table
-    with a custom table, this is that custom table.
-    :return: None.
-    """
-    fields: List[Field] = [class_.__dataclass_fields__[key] for
-                           key in class_.__dataclass_fields__.keys()]
-    fields.sort(key=lambda field: field.name)  # Since dictionaries *may* be unsorted.
-    sql_fields = ', '.join(f"{field.name} {_convert_type(field.type, type_overload)}"
-                           f"{_get_default(field.default, type_overload)}" for field in fields)
-    sql_fields = "obj_id INTEGER PRIMARY KEY AUTOINCREMENT, " + sql_fields
-    cursor.execute(f"CREATE TABLE IF NOT EXISTS {class_.__name__.lower()} ({sql_fields});")
+from .commons import _convert_sql_format, _convert_type, _create_table, type_table
 
 
 def _create_entry(self) -> None:
@@ -105,14 +72,14 @@ def datalite(db_path: str, type_overload: Optional[Dict[Optional[type], str]] =
     :return: The new dataclass.
     """
     def decorator(dataclass_: type, *args_i, **kwargs_i):
-        type_table: Dict[Optional[type], str] = {None: "NULL", int: "INTEGER", float: "REAL",
-                                                 str: "TEXT", bytes: "BLOB"}
+        types_table = type_table.copy()
         if type_overload is not None:
-            type_table.update(type_overload)
+            types_table.update(type_overload)
         with sql.connect(db_path) as con:
             cur: sql.Cursor = con.cursor()
-            _create_table(dataclass_, cur, type_table)
+            _create_table(dataclass_, cur, types_table)
         setattr(dataclass_, 'db_path', db_path)  # We add the path of the database to class itself.
+        setattr(dataclass_, 'types_table', types_table)  # We add the type table for migration.
         dataclass_.create_entry = _create_entry
         dataclass_.remove_entry = _remove_entry
         dataclass_.update_entry = _update_entry

datalite/fetch.py

@@ -1,6 +1,6 @@
 import sqlite3 as sql
 from typing import List, Tuple, Any
-from .commons import _convert_sql_format
+from .commons import _convert_sql_format, _get_table_cols
 
 
 def _insert_pagination(query: str, page: int, element_count: int) -> str:
@@ -35,18 +35,6 @@ def is_fetchable(class_: type, obj_id: int) -> bool:
     return bool(cur.fetchall())
 
 
-def _get_table_cols(cur: sql.Cursor, table_name: str) -> List[str]:
-    """
-    Get the column data of a table.
-
-    :param cur: Cursor in database.
-    :param table_name: Name of the table.
-    :return: the information about columns.
-    """
-    cur.execute(f"PRAGMA table_info({table_name});")
-    return [row_info[1] for row_info in cur.fetchall()][1:]
-
-
 def fetch_equals(class_: type, field: str, value: Any, ) -> Any:
     """
     Fetch a class_ type variable from its bound db.
@@ -112,7 +100,7 @@ def fetch_if(class_: type, condition: str, page: int = 0, element_count: int = 1
     :param page: Which page to retrieve, default all. (0 means closed).
     :param element_count: Element count in each page.
     :return: A tuple of records that fit the given condition
-    of given type class_.
+        of given type class_.
     """
     table_name = class_.__name__.lower()
     with sql.connect(getattr(class_, 'db_path')) as con:
@@ -146,7 +134,7 @@ def fetch_range(class_: type, range_: range) -> tuple:
     :param class_: Class of the records.
     :param range_: Range of the object ids.
     :return: A tuple of class_ type objects whose values
-    come from the class_' bound database.
+        come from the class_' bound database.
     """
     return tuple(fetch_from(class_, obj_id) for obj_id in range_ if is_fetchable(class_, obj_id))
 
@@ -159,7 +147,7 @@ def fetch_all(class_: type, page: int = 0, element_count: int = 10) -> tuple:
     :param page: Which page to retrieve, default all. (0 means closed).
     :param element_count: Element count in each page.
     :return: All the records of type class_ in
-    the bound database as a tuple.
+        the bound database as a tuple.
     """
     try:
         db_path = getattr(class_, 'db_path')

datalite/migrations.py

@@ -0,0 +1,160 @@
+"""
+Migrations module deals with migrating data when the object
+definitions change. This functions deal with Schema Migrations.
+"""
+from dataclasses import Field
+from os.path import exists
+from typing import Dict, Tuple, List
+import sqlite3 as sql
+
+from .commons import _create_table, _get_table_cols
+
+
+def _get_db_table(class_: type) -> Tuple[str, str]:
+    """
+    Check if the class is a datalite class, the database exists
+    and the table exists. Return database and table names.
+
+    :param class_: A datalite class.
+    :return: A tuple of database and table names.
+    """
+    database_name: str = getattr(class_, 'db_path', None)
+    if not database_name:
+        raise TypeError(f"{class_.__name__} is not a datalite class.")
+    table_name: str = class_.__name__.lower()
+    if not exists(database_name):
+        raise FileNotFoundError(f"{database_name} does not exist")
+    with sql.connect(database_name) as con:
+        cur: sql.Cursor = con.cursor()
+        cur.execute(f"SELECT count(*) FROM sqlite_master "
+                    f"WHERE type='table' AND name='{table_name}';")
+        count: int = int(cur.fetchone()[0])
+    if not count:
+        raise FileExistsError(f"Table, {table_name}, already exists.")
+    return database_name, table_name
+
+
+def _get_table_column_names(database_name: str, table_name: str) -> Tuple[str]:
+    """
+    Get the column names of table.
+
+    :param database_name: Name of the database the table
+        resides in.
+    :param table_name: Name of the table.
+    :return: A tuple holding the column names of the table.
+    """
+    with sql.connect(database_name) as con:
+        cur: sql.Cursor = con.cursor()
+        cols: List[str] = _get_table_cols(cur, table_name)
+    return tuple(cols)
+
+
+def _copy_records(database_name: str, table_name: str):
+    """
+    Copy all records from a table.
+
+    :param database_name: Name of the database.
+    :param table_name: Name of the table.
+    :return: A generator holding dataclass asdict representations.
+    """
+    with sql.connect(database_name) as con:
+        cur: sql.Cursor = con.cursor()
+        cur.execute(f'SELECT * FROM {table_name};')
+        values = cur.fetchall()
+        keys = _get_table_cols(cur, table_name)
+        keys.insert(0, 'obj_id')
+    records = (dict(zip(keys, value)) for value in values)
+    return records
+
+
+def _drop_table(database_name: str, table_name: str) -> None:
+    """
+    Drop a table.
+
+    :param database_name: Name of the database.
+    :param table_name: Name of the table to be dropped.
+    :return: None.
+    """
+    with sql.connect(database_name) as con:
+        cur: sql.Cursor = con.cursor()
+        cur.execute(f'DROP TABLE {table_name};')
+        con.commit()
+
+
+def _modify_records(data, col_to_del: Tuple[str], col_to_add: Tuple[str],
+                    flow: Dict[str, str]) -> Tuple[Dict[str, str]]:
+    """
+    Modify the asdict records in accordance
+        with schema migration rules provided.
+
+    :param data: Data kept as asdict in tuple.
+    :param col_to_del: Column names to delete.
+    :param col_to_add: Column names to add.
+    :param flow: A dictionary that explain
+        if the data from a deleted column
+        will be transferred to a column
+        to be added.
+    :return: The modified data records.
+    """
+    records = []
+    for record in data:
+        record_mod = {}
+        for key in record.keys():
+            if key in col_to_del and key in flow:
+                record_mod[flow[key]] = record[key]
+            else:
+                record_mod[key] = record[key]
+        for key_to_add in col_to_add:
+            if key_to_add not in record_mod:
+                record_mod[key_to_add] = None
+        records.append(record_mod)
+    return records
+
+
+def _migrate_records(class_: type, database_name: str, data,
+                     col_to_del: Tuple[str], col_to_add: Tuple[str], flow: Dict[str, str]) -> None:
+    """
+    Migrate the records into the modified table.
+
+    :param class_: Class of the entries.
+    :param database_name: Name of the database.
+    :param data: Data, asdict tuple.
+    :param col_to_del: Columns to be deleted.
+    :param col_to_add: Columns to be added.
+    :param flow: Flow dictionary stating where
+        column data will be transferred.
+    :return: None.
+    """
+    with sql.connect(database_name) as con:
+        cur: sql.Cursor = con.cursor()
+        _create_table(class_, cur, getattr(class_, 'types_table'))
+        con.commit()
+    new_records = _modify_records(data, col_to_del, col_to_add, flow)
+    for record in new_records:
+        del record['obj_id']
+        class_(**record).create_entry()
+
+
+def basic_migrate(class_: type, column_transfer: dict = None) -> None:
+    """
+    Given a class, compare its previous table,
+    delete the fields that no longer exist,
+    create new columns for new fields. If the
+    column_flow parameter is given, migrate elements
+    from previous column to the new ones.
+
+    :param class_: Datalite class to migrate.
+    :param column_transfer: A dictionary showing which
+        columns will be copied to new ones.
+    :return: None.
+    """
+    database_name, table_name = _get_db_table(class_)
+    table_column_names: Tuple[str] = _get_table_column_names(database_name, table_name)
+    values = class_.__dataclass_fields__.values()
+    data_fields: Tuple[Field] = tuple(field for field in values)
+    data_field_names: Tuple[str] = tuple(field.name for field in data_fields)
+    columns_to_be_deleted: Tuple[str] = tuple(column for column in table_column_names if column not in data_field_names)
+    columns_to_be_added: Tuple[str] = tuple(column for column in data_field_names if column not in table_column_names)
+    records = _copy_records(database_name, table_name)
+    _drop_table(database_name, table_name)
+    _migrate_records(class_, database_name, records, columns_to_be_deleted, columns_to_be_added, column_transfer)

docs/_build/html/_sources/datalite.rst.txt

@@ -14,4 +14,10 @@ datalite.fetch module
    :undoc-members:
    :show-inheritance:
 
+datalite.migrations module
+----------------------------
 
+.. automodule:: datalite.migrations
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/_build/html/datalite.html

@@ -36,7 +36,7 @@
     
     <link rel="index" title="Index" href="genindex.html" />
     <link rel="search" title="Search" href="search.html" />
-    <link rel="prev" title="datalite" href="modules.html" /> 
+    <link rel="prev" title="Welcome to Datalite’s documentation!" href="index.html" /> 
 </head>
 
 <body class="wy-body-for-nav">
@@ -83,12 +83,10 @@
             
               <p class="caption"><span class="caption-text">Contents:</span></p>
 <ul class="current">
-<li class="toctree-l1 current"><a class="reference internal" href="modules.html">datalite</a><ul class="current">
-<li class="toctree-l2 current"><a class="current reference internal" href="#">datalite package</a><ul>
-<li class="toctree-l3"><a class="reference internal" href="#datalite-module">datalite Module</a></li>
-<li class="toctree-l3"><a class="reference internal" href="#module-datalite.fetch">datalite.fetch module</a></li>
-</ul>
-</li>
+<li class="toctree-l1 current"><a class="current reference internal" href="#">datalite package</a><ul>
+<li class="toctree-l2"><a class="reference internal" href="#datalite-module">datalite Module</a></li>
+<li class="toctree-l2"><a class="reference internal" href="#module-datalite.fetch">datalite.fetch module</a></li>
+<li class="toctree-l2"><a class="reference internal" href="#module-datalite.migrations">datalite.migrations module</a></li>
 </ul>
 </li>
 </ul>
@@ -137,8 +135,6 @@
     
       <li><a href="index.html" class="icon icon-home"></a> &raquo;</li>
         
-          <li><a href="modules.html">datalite</a> &raquo;</li>
-        
       <li>datalite package</li>
     
     
@@ -196,10 +192,10 @@
 </ul>
 </dd>
 <dt class="field-even">Returns</dt>
-<dd class="field-even"><p>All the records of type <a href="#id1"><span class="problematic" id="id2">class_</span></a> in</p>
+<dd class="field-even"><p>All the records of type <a href="#id1"><span class="problematic" id="id2">class_</span></a> in
+the bound database as a tuple.</p>
 </dd>
 </dl>
-<p>the bound database as a tuple.</p>
 </dd></dl>
 
 <dl class="py function">
@@ -252,10 +248,10 @@ provided they fit the given condition</p>
 </ul>
 </dd>
 <dt class="field-even">Returns</dt>
-<dd class="field-even"><p>A tuple of records that fit the given condition</p>
+<dd class="field-even"><p>A tuple of records that fit the given condition
+of given type <a href="#id9"><span class="problematic" id="id10">class_</span></a>.</p>
 </dd>
 </dl>
-<p>of given type <a href="#id9"><span class="problematic" id="id10">class_</span></a>.</p>
 </dd></dl>
 
 <dl class="py function">
@@ -270,10 +266,10 @@ provided they fit the given condition</p>
 </ul>
 </dd>
 <dt class="field-even">Returns</dt>
-<dd class="field-even"><p>A tuple of <a href="#id11"><span class="problematic" id="id12">class_</span></a> type objects whose values</p>
+<dd class="field-even"><p>A tuple of <a href="#id11"><span class="problematic" id="id12">class_</span></a> type objects whose values
+come from the <a href="#id13"><span class="problematic" id="id14">class_</span></a>’ bound database.</p>
 </dd>
 </dl>
-<p>come from the <a href="#id13"><span class="problematic" id="id14">class_</span></a>’ bound database.</p>
 </dd></dl>
 
 <dl class="py function">
@@ -316,6 +312,33 @@ given value.</p>
 </dl>
 </dd></dl>
 
+</div>
+<div class="section" id="module-datalite.migrations">
+<span id="datalite-migrations-module"></span><h2>datalite.migrations module<a class="headerlink" href="#module-datalite.migrations" title="Permalink to this headline">¶</a></h2>
+<p>Migrations module deals with migrating data when the object
+definitions change. This functions deal with Schema Migrations.</p>
+<dl class="py function">
+<dt id="datalite.migrations.basic_migrate">
+<code class="sig-prename descclassname">datalite.migrations.</code><code class="sig-name descname">basic_migrate</code><span class="sig-paren">(</span><em class="sig-param"><span class="n">class_</span><span class="p">:</span> <span class="n">type</span></em>, <em class="sig-param"><span class="n">column_transfer</span><span class="p">:</span> <span class="n">dict</span> <span class="o">=</span> <span class="default_value">None</span></em><span class="sig-paren">)</span> &#x2192; None<a class="headerlink" href="#datalite.migrations.basic_migrate" title="Permalink to this definition">¶</a></dt>
+<dd><p>Given a class, compare its previous table,
+delete the fields that no longer exist,
+create new columns for new fields. If the
+column_flow parameter is given, migrate elements
+from previous column to the new ones.</p>
+<dl class="field-list simple">
+<dt class="field-odd">Parameters</dt>
+<dd class="field-odd"><ul class="simple">
+<li><p><strong>class</strong> – Datalite class to migrate.</p></li>
+<li><p><strong>column_transfer</strong> – A dictionary showing which
+columns will be copied to new ones.</p></li>
+</ul>
+</dd>
+<dt class="field-even">Returns</dt>
+<dd class="field-even"><p>None.</p>
+</dd>
+</dl>
+</dd></dl>
+
 </div>
 </div>
 
@@ -328,7 +351,7 @@ given value.</p>
     <div class="rst-footer-buttons" role="navigation" aria-label="footer navigation">
       
       
-        <a href="modules.html" class="btn btn-neutral float-left" title="datalite" accesskey="p" rel="prev"><span class="fa fa-arrow-circle-left"></span> Previous</a>
+        <a href="index.html" class="btn btn-neutral float-left" title="Welcome to Datalite’s documentation!" accesskey="p" rel="prev"><span class="fa fa-arrow-circle-left"></span> Previous</a>
       
     </div>
   

docs/_build/html/genindex.html

@@ -150,24 +150,40 @@
 <h1 id="index">Index</h1>
 
 <div class="genindex-jumpbox">
- <a href="#D"><strong>D</strong></a>
+ <a href="#B"><strong>B</strong></a>
+ | <a href="#D"><strong>D</strong></a>
  | <a href="#F"><strong>F</strong></a>
  | <a href="#I"><strong>I</strong></a>
  | <a href="#M"><strong>M</strong></a>
  
 </div>
+<h2 id="B">B</h2>
+<table style="width: 100%" class="indextable genindextable"><tr>
+  <td style="width: 33%; vertical-align: top;"><ul>
+      <li><a href="datalite.html#datalite.migrations.basic_migrate">basic_migrate() (in module datalite.migrations)</a>
+</li>
+  </ul></td>
+</tr></table>
+
 <h2 id="D">D</h2>
 <table style="width: 100%" class="indextable genindextable"><tr>
   <td style="width: 33%; vertical-align: top;"><ul>
       <li><a href="datalite.html#datalite.datalite">datalite() (in module datalite)</a>
 </li>
-  </ul></td>
-  <td style="width: 33%; vertical-align: top;"><ul>
       <li>
     datalite.fetch
 
       <ul>
         <li><a href="datalite.html#module-datalite.fetch">module</a>
+</li>
+      </ul></li>
+  </ul></td>
+  <td style="width: 33%; vertical-align: top;"><ul>
+      <li>
+    datalite.migrations
+
+      <ul>
+        <li><a href="datalite.html#module-datalite.migrations">module</a>
 </li>
       </ul></li>
   </ul></td>
@@ -209,6 +225,8 @@
 
       <ul>
         <li><a href="datalite.html#module-datalite.fetch">datalite.fetch</a>
+</li>
+        <li><a href="datalite.html#module-datalite.migrations">datalite.migrations</a>
 </li>
       </ul></li>
   </ul></td>

docs/_build/html/index.html

@@ -162,6 +162,7 @@ sqlite3 database.</p>
 <li class="toctree-l1"><a class="reference internal" href="datalite.html">datalite package</a><ul>
 <li class="toctree-l2"><a class="reference internal" href="datalite.html#datalite-module">datalite Module</a></li>
 <li class="toctree-l2"><a class="reference internal" href="datalite.html#module-datalite.fetch">datalite.fetch module</a></li>
+<li class="toctree-l2"><a class="reference internal" href="datalite.html#module-datalite.migrations">datalite.migrations module</a></li>
 </ul>
 </li>
 </ul>

docs/_build/html/objects.inv

@@ -2,4 +2,6 @@
 # Project: Datalite
 # Version: 
 # The remainder of this file is compressed using zlib.
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docs/_build/html/py-modindex.html

@@ -169,6 +169,11 @@
        <td>&#160;&#160;&#160;
        <a href="datalite.html#module-datalite.fetch"><code class="xref">datalite.fetch</code></a></td><td>
        <em></em></td></tr>
+     <tr class="cg-1">
+       <td></td>
+       <td>&#160;&#160;&#160;
+       <a href="datalite.html#module-datalite.migrations"><code class="xref">datalite.migrations</code></a></td><td>
+       <em></em></td></tr>
    </table>
 
 

docs/_build/html/searchindex.js

@@ -1 +1 @@
-Search.setIndex({docnames:["datalite","index","modules"],envversion:{"sphinx.domains.c":2,"sphinx.domains.changeset":1,"sphinx.domains.citation":1,"sphinx.domains.cpp":3,"sphinx.domains.index":1,"sphinx.domains.javascript":2,"sphinx.domains.math":2,"sphinx.domains.python":2,"sphinx.domains.rst":2,"sphinx.domains.std":1,sphinx:56},filenames:["datalite.rst","index.rst","modules.rst"],objects:{"datalite.fetch":{fetch_all:[0,0,1,""],fetch_equals:[0,0,1,""],fetch_from:[0,0,1,""],fetch_if:[0,0,1,""],fetch_range:[0,0,1,""],fetch_where:[0,0,1,""],is_fetchable:[0,0,1,""]},datalite:{datalite:[0,0,1,""],fetch:[0,1,0,"-"]}},objnames:{"0":["py","function","Python function"],"1":["py","module","Python module"]},objtypes:{"0":"py:function","1":"py:module"},terms:{"class":0,"default":0,"int":0,"new":0,"return":0,The:0,add:0,all:0,ani:0,arg:[],argument:[],bind:[0,1],bool:0,bound:0,callabl:0,can:1,check:0,class_:0,close:0,come:0,common:[],condit:0,content:[],convert:[],count:0,create_entri:0,data:0,databas:[0,1],dataclass:[0,1],datalite_decor:[],db_path:0,decor:[],defin:[],dict:0,dictionari:0,each:0,element:0,element_count:0,fetch:[1,2],fetch_al:0,fetch_equ:0,fetch_from:0,fetch_if:0,fetch_rang:0,fetch_wher:0,fetchabl:0,fetchal:0,field:0,fit:0,from:0,get:[],given:0,ids:0,index:1,insert:[],insert_pagin:[],is_fetch:0,its:0,kwarg:[],librari:1,mean:0,method:0,modifi:[],modul:[1,2],none:0,number:[],obj_id:0,object:0,option:0,overload:0,packag:[1,2],page:[0,1],pagin:[],param:[],paramet:0,path:0,provid:0,python:1,queri:[],rang:0,range_:0,record:0,remove_entri:0,remove_from:[],retriev:0,search:1,simpl:1,sqlite3:[0,1],str:0,submodul:[],taken:0,thei:0,thi:0,tupl:0,type:0,type_overload:0,uniqu:0,update_entri:0,use:1,used:[],valu:0,variabl:0,which:0,whose:0},titles:["datalite package","Welcome to Datalite\u2019s documentation!","datalite"],titleterms:{common:[],content:1,datalit:[0,1,2],datalite_decor:[],document:1,fetch:0,indic:1,modul:0,packag:0,submodul:[],tabl:1,welcom:1}})
+Search.setIndex({docnames:["datalite","index"],envversion:{"sphinx.domains.c":2,"sphinx.domains.changeset":1,"sphinx.domains.citation":1,"sphinx.domains.cpp":3,"sphinx.domains.index":1,"sphinx.domains.javascript":2,"sphinx.domains.math":2,"sphinx.domains.python":2,"sphinx.domains.rst":2,"sphinx.domains.std":1,sphinx:56},filenames:["datalite.rst","index.rst"],objects:{"datalite.fetch":{fetch_all:[0,0,1,""],fetch_equals:[0,0,1,""],fetch_from:[0,0,1,""],fetch_if:[0,0,1,""],fetch_range:[0,0,1,""],fetch_where:[0,0,1,""],is_fetchable:[0,0,1,""]},"datalite.migrations":{basic_migrate:[0,0,1,""]},datalite:{datalite:[0,0,1,""],fetch:[0,1,0,"-"],migrations:[0,1,0,"-"]}},objnames:{"0":["py","function","Python function"],"1":["py","module","Python module"]},objtypes:{"0":"py:function","1":"py:module"},terms:{"class":0,"default":0,"function":0,"int":0,"new":0,"return":0,The:0,add:0,all:0,ani:0,arg:[],argument:[],basic_migr:0,bind:[0,1],bool:0,bound:0,callabl:0,can:1,chang:0,check:0,class_:0,close:0,column:0,column_flow:0,column_transf:0,come:0,common:[],compar:0,condit:0,content:[],convert:[],copi:0,count:0,creat:0,create_entri:0,data:0,databas:[0,1],dataclass:[0,1],datalite_decor:[],db_path:0,deal:0,decor:[],defin:[],definit:0,delet:0,dict:0,dictionari:0,each:0,element:0,element_count:0,exist:0,fetch:1,fetch_al:0,fetch_equ:0,fetch_from:0,fetch_if:0,fetch_rang:0,fetch_wher:0,fetchabl:0,fetchal:0,field:0,fit:0,from:0,get:[],given:0,ids:0,index:1,insert:[],insert_pagin:[],is_fetch:0,its:0,kwarg:[],librari:1,longer:0,mean:0,method:0,migrat:1,modifi:[],modul:1,none:0,number:[],obj_id:0,object:0,ones:0,option:0,overload:0,packag:1,page:[0,1],pagin:[],param:[],paramet:0,path:0,previou:0,provid:0,python:1,queri:[],rang:0,range_:0,record:0,remove_entri:0,remove_from:[],retriev:0,schema:0,search:1,show:0,simpl:1,sqlite3:[0,1],str:0,submodul:[],tabl:0,taken:0,thei:0,thi:0,tupl:0,type:0,type_overload:0,uniqu:0,update_entri:0,use:1,used:[],valu:0,variabl:0,when:0,which:0,whose:0},titles:["datalite package","Welcome to Datalite\u2019s documentation!"],titleterms:{common:[],content:1,datalit:[0,1],datalite_decor:[],document:1,fetch:0,indic:1,migrat:0,modul:0,packag:0,submodul:[],tabl:1,welcom:1}})

docs/conf.py

@@ -23,7 +23,7 @@ copyright = '2020, Ege Ozkan'
 author = 'Ege Ozkan'
 
 # The full version, including alpha/beta/rc tags
-release = 'v0.5.2'
+release = 'v0.5.3'
 
 
 # -- General configuration ---------------------------------------------------

docs/datalite.rst

@@ -14,4 +14,10 @@ datalite.fetch module
    :undoc-members:
    :show-inheritance:
 
+datalite.migrations module
+----------------------------
 
+.. automodule:: datalite.migrations
+   :members:
+   :undoc-members:
+   :show-inheritance:

docs/modules.rst

@@ -1,7 +0,0 @@
-datalite
-========
-
-.. toctree::
-   :maxdepth: 4
-
-   datalite

setup.py

@@ -5,7 +5,7 @@ with open("README.md", "r") as fh:
 
 setuptools.setup(
     name="datalite", # Replace with your own username
-    version="0.5.2",
+    version="0.5.3",
     author="Ege Ozkan",
     author_email="egeemirozkan24@gmail.com",
     description="A small package that binds dataclasses to an sqlite database",

test/main_tests.py

@@ -6,6 +6,8 @@ from dataclasses import dataclass, asdict
 from math import floor
 from os import remove
 
+from datalite.migrations import basic_migrate, _drop_table
+
 
 @datalite(db_path='test.db')
 @dataclass
@@ -28,6 +30,17 @@ class FetchClass:
     def __eq__(self, other):
         return asdict(self) == asdict(other)
 
+@datalite(db_path='test.db')
+@dataclass
+class Migrate1:
+    ordinal: int
+
+
+@datalite(db_path='test.db')
+@dataclass
+class Migrate2:
+    cardinal: int
+
 
 def getValFromDB(obj_id = 1):
     with connect('test.db') as db:
@@ -127,5 +140,25 @@ class DatabaseFetchPaginationCalls(unittest.TestCase):
     def tearDown(self) -> None:
         [obj.remove_entry() for obj in self.objs]
 
+
+class DatabaseMigration(unittest.TestCase):
+    def setUp(self) -> None:
+        self.objs = [Migrate1(i) for i in range(10)]
+        [obj.create_entry() for obj in self.objs]
+
+    def testBasicMigrate(self):
+        global Migrate1, Migrate2
+        Migrate1 = Migrate2
+        Migrate1.__name__ = 'Migrate1'
+        basic_migrate(Migrate1, {'ordinal': 'cardinal'})
+        t_objs = fetch_all(Migrate1)
+        self.assertEqual([obj.ordinal for obj in self.objs], [obj.cardinal for obj in t_objs])
+
+    def tearDown(self) -> None:
+        t_objs = fetch_all(Migrate1)
+        [obj.remove_entry() for obj in t_objs]
+        _drop_table('test.db', 'migrate1')
+
+
 if __name__ == '__main__':
     unittest.main()