pagination support

Author: daimor

django_iris/compiler.py

@@ -0,0 +1,171 @@
+from django.core.exceptions import EmptyResultSet
+from django.db.models.expressions import Col
+from django.db.models.sql import compiler
+
+class SQLCompiler(compiler.SQLCompiler):
+    def as_sql(self, with_limits=True, with_col_aliases=False):
+        with_limit_offset = with_limits and (
+            self.query.high_mark is not None or self.query.low_mark
+        )
+        print('LIMIT - ' + str(self.query.low_mark) + ':' + str(self.query.high_mark))
+        if self.query.select_for_update or not with_limit_offset:
+            return super().as_sql(with_limits, with_col_aliases)
+        try:
+            extra_select, order_by, group_by = self.pre_sql_setup()
+
+            limit, offset = self.connection.ops._get_limit_offset_params(self.query.low_mark, self.query.high_mark)
+
+            distinct_fields, distinct_params = self.get_distinct()
+            # This must come after 'select', 'ordering', and 'distinct'
+            # (see docstring of get_from_clause() for details).
+            from_, f_params = self.get_from_clause()
+            try:
+                where, w_params = (
+                    self.compile(self.where) if self.where is not None else ("", [])
+                )
+            except EmptyResultSet:
+                if self.elide_empty:
+                    raise
+                # Use a predicate that's always False.
+                where, w_params = "0 = 1", []
+            having, h_params = (
+                self.compile(self.having) if self.having is not None else ("", [])
+            )
+            result = ["SELECT"]
+            params = []
+
+            if not offset:
+                result.append("TOP %d" % limit)
+
+            if self.query.distinct:
+                distinct_result, distinct_params = self.connection.ops.distinct_sql(
+                    distinct_fields,
+                    distinct_params,
+                )
+                result += distinct_result
+                params += distinct_params
+
+            out_cols = []
+            col_idx = 1
+            for _, (s_sql, s_params), alias in self.select + extra_select:
+                if alias:
+                    s_sql = "%s AS %s" % (
+                        s_sql,
+                        self.connection.ops.quote_name(alias),
+                    )
+                elif with_col_aliases:
+                    s_sql = "%s AS %s" % (
+                        s_sql,
+                        self.connection.ops.quote_name("col%d" % col_idx),
+                    )
+                    col_idx += 1
+                params.extend(s_params)
+                out_cols.append(s_sql)
+
+            order_by_result = ""
+            if order_by:
+                ordering = []
+                for _, (o_sql, o_params, _) in order_by:
+                    ordering.append(o_sql)
+                    params.extend(o_params)
+                order_by_result = "ORDER BY %s" % ", ".join(ordering)
+                if offset:
+                    out_cols.append("ROW_NUMBER() OVER (%s) AS row_number" % order_by_result)
+
+            result += [", ".join(out_cols), "FROM", *from_]
+            params.extend(f_params)
+
+            if where:
+                result.append("WHERE %s" % where)
+                params.extend(w_params)
+
+            grouping = []
+            for g_sql, g_params in group_by:
+                grouping.append(g_sql)
+                params.extend(g_params)
+            if grouping:
+                if distinct_fields:
+                    raise NotImplementedError(
+                        "annotate() + distinct(fields) is not implemented."
+                    )
+                order_by = order_by or self.connection.ops.force_no_ordering()
+                result.append("GROUP BY %s" % ", ".join(grouping))
+                if self._meta_ordering:
+                    order_by = None
+            if having:
+                result.append("HAVING %s" % having)
+                params.extend(h_params)
+
+            if self.query.explain_info:
+                result.insert(
+                    0,
+                    self.connection.ops.explain_query_prefix(
+                        self.query.explain_info.format,
+                        **self.query.explain_info.options,
+                    ),
+                )
+
+            if order_by_result and not offset:
+                result.append(order_by_result)
+
+            query = " ".join(result)
+
+            if self.query.subquery and extra_select:
+                # If the query is used as a subquery, the extra selects would
+                # result in more columns than the left-hand side expression is
+                # expecting. This can happen when a subquery uses a combination
+                # of order_by() and distinct(), forcing the ordering expressions
+                # to be selected as well. Wrap the query in another subquery
+                # to exclude extraneous selects.
+                sub_selects = []
+                sub_params = []
+                for index, (select, _, alias) in enumerate(self.select, start=1):
+                    if not alias and with_col_aliases:
+                        alias = "col%d" % index
+                    if alias:
+                        sub_selects.append(
+                            "%s.%s"
+                            % (
+                                self.connection.ops.quote_name("subquery"),
+                                self.connection.ops.quote_name(alias),
+                            )
+                        )
+                    else:
+                        select_clone = select.relabeled_clone(
+                            {select.alias: "subquery"}
+                        )
+                        subselect, subparams = select_clone.as_sql(
+                            self, self.connection
+                        )
+                        sub_selects.append(subselect)
+                        sub_params.extend(subparams)
+                query = "SELECT %s FROM (%s) subquery" % (
+                    ", ".join(sub_selects),
+                    query,
+                ), tuple(sub_params + params)
+
+            if offset:
+                query = "SELECT * FROM (%s) WHERE row_number between %d AND %d ORDER BY row_number" % (
+                    query,
+                    limit,
+                    offset,
+                )
+            return query, tuple(params)
+        except:
+            return super().as_sql(with_limits, with_col_aliases)
+
+
+class SQLInsertCompiler(compiler.SQLInsertCompiler, SQLCompiler):
+    pass
+
+
+class SQLDeleteCompiler(compiler.SQLDeleteCompiler, SQLCompiler):
+    pass
+
+
+class SQLUpdateCompiler(compiler.SQLUpdateCompiler, SQLCompiler):
+    pass
+    
+
+class SQLAggregateCompiler(compiler.SQLAggregateCompiler, SQLCompiler):
+    pass

django_iris/introspection.py

@@ -87,8 +87,6 @@ def get_table_description(self, cursor, table_name):
                        )
 
         description = [
-            # name type_code display_size internal_size precision scale null_ok default collation
-            # auto_increment
             FieldInfo(
                 name,
                 'longvarchar'

django_iris/operations.py

@@ -10,7 +10,7 @@
 
 class DatabaseOperations(BaseDatabaseOperations):
 
-    # compiler_module = "django_iris.compiler"
+    compiler_module = "django_iris.compiler"
 
     def quote_name(self, name):
         if name.startswith('"') and name.endswith('"'):