[open-ils-commits] r16641 - trunk/Open-ILS/src/c-apps (scottmk)
svn at svn.open-ils.org
svn at svn.open-ils.org
Wed Jun 9 17:39:18 EDT 2010
Author: scottmk
Date: 2010-06-09 17:39:12 -0400 (Wed, 09 Jun 2010)
New Revision: 16641
Modified:
trunk/Open-ILS/src/c-apps/oils_storedq.c
Log:
Rewrote the implementation of the open-ils.qstore.columns method.
The old implementation examined the SELECT clause(s) as encoded
in the query.select_item and query.expression tables. The new
implementation performs a dummy query, and then returns the
field names from the database result.
Advantages of the new implementation:
1. It doesn't get confused by wild cards in the SELECT clause.
2. It provides a field name for every column, including those
which are function calls, subqueries, or other expressions.
(Of course these names may not be very revealing, such as
"?column?".)
Disadvantages:
1. The resulting field names are not qualified by table name.
2. Additional overhead due to the additional database call.
M Open-ILS/src/c-apps/oils_storedq.c
Modified: trunk/Open-ILS/src/c-apps/oils_storedq.c
===================================================================
--- trunk/Open-ILS/src/c-apps/oils_storedq.c 2010-06-09 20:15:18 UTC (rev 16640)
+++ trunk/Open-ILS/src/c-apps/oils_storedq.c 2010-06-09 21:39:12 UTC (rev 16641)
@@ -72,6 +72,79 @@
static int verbose = 0;
/**
+ @brief Build a list of column names for a specified query.
+ @param state Pointer to the query-building context.
+ @param query Pointer to the specified query.
+ @return Pointer to a newly-allocated JSON_ARRAY of column names, if successful;
+ otherwise NULL.
+
+ The column names are those assigned by PostgreSQL, e.g.:
+ - a column alias, if an AS clause defines one
+ - a column name (not qualified by a table name or alias, even if the query
+ specifies one)
+ - where the item is a function call, the name of the function
+ - where the item is a subquery or other expression, whatever PostgreSQL decides on,
+ typically '?column?'
+
+ The resulting column names may include duplicates.
+
+ The calling code is responsible for freeing the list by calling jsonObjectFree().
+*/
+jsonObject* oilsGetColNames( BuildSQLState* state, StoredQ* query ) {
+ if( !state || !query ) return NULL;
+
+ // Build SQL in the usual way (with some temporary option settings)
+ int defaults_usable = state->defaults_usable;
+ int values_required = state->values_required;
+ state->defaults_usable = 1; // We can't execute the test query unless we
+ state->values_required = 1; // have a value for every bind variable.
+ int rc = buildSQL( state, query );
+ state->defaults_usable = defaults_usable;
+ state->values_required = values_required;
+ if( rc ) {
+ osrfLogWarning( OSRF_LOG_MARK, sqlAddMsg( state,
+ "Unable to build SQL statement for query id # %d", query->id ));
+ state->error = 1;
+ return NULL;
+ }
+
+ // Wrap it in an outer query to get the column names, but no rows
+ growing_buffer* wrapper = buffer_init( 80 + strlen( OSRF_BUFFER_C_STR( state->sql )));
+ buffer_add( wrapper, "SELECT \"phony query\".* FROM (" );
+ buffer_add( wrapper, OSRF_BUFFER_C_STR( state->sql ));
+ buffer_chomp( wrapper ); // remove the terminating newline
+ buffer_chomp( wrapper ); // remove the terminating semicolon
+ buffer_add( wrapper, ") AS \"phony query\" WHERE FALSE;" );
+
+ // Execute the wrapped query
+ dbi_result result = dbi_conn_query( state->dbhandle, OSRF_BUFFER_C_STR( wrapper ));
+ buffer_free( wrapper );
+ if( !result ) {
+ const char* msg;
+ int errnum = dbi_conn_error( state->dbhandle, &msg );
+ osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+ "Unable to execute dummy query for column names: #%d %s",
+ errnum, msg ? msg : "No description available" ));
+ state->error = 1;
+ return NULL;
+ }
+
+ // Examine the query result to get the column names
+
+ unsigned int num_cols = dbi_result_get_numfields( result );
+ jsonObject* cols = jsonNewObjectType( JSON_ARRAY );
+ unsigned int i;
+ for( i = 1; i <= num_cols; ++i ) {
+ const char* fname = dbi_result_get_field_name( result, i );
+ if( fname )
+ jsonObjectPush( cols, jsonNewObject( fname ));
+ }
+
+ dbi_result_free( result );
+ return cols;
+}
+
+/**
@brief Load a stored query.
@param state Pointer to the query-building context.
@param query_id ID of the query in query.stored_query.
@@ -998,7 +1071,14 @@
else if( !strcmp( type_str, "string_list" ))
type = BIND_STR_LIST;
else if( !strcmp( type_str, "number_list" ))
- type = BIND_NUM_LIST;;
+ type = BIND_NUM_LIST;
+ else { // Shouldn't happen due to database constraint...
+ osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
+ "Internal error: invalid bind variable type \"%s\" for bind variable \"%s\"",
+ type_str, name ));
+ state->error = 1;
+ return NULL;
+ }
const char* description = dbi_result_get_string_idx( result, 3 );
@@ -1734,71 +1814,6 @@
}
/**
- @brief Build a list of column names for a specified query.
- @param state Pointer to the query-building context.
- @param query Pointer to the specified query.
- @return Pointer to a newly-allocated JSON_ARRAY of column names.
-
- In the resulting array, each entry is either a JSON_STRING or (when no column name is
- available) a JSON_NULL.
-
- The calling code is responsible for freeing the list by calling jsonObjectFree().
-*/
-jsonObject* oilsGetColNames( BuildSQLState* state, StoredQ* query ) {
- if( !state || !query )
- return NULL;
-
- // Save the outermost query id for possible use in an error message
- int id = query->id;
-
- while( query->type != QT_SELECT ) {
- // If the query is a UNION, INTERSECT, or EXCEPT, there must be a SELECT in
- // there somewhere. Find the first one, and use the SELECT list from that.
- QSeq* child_list = query->child_list;
- if( !child_list ) {
- query = NULL;
- break;
- } else
- query = child_list->child_query;
- }
-
- if( !query ) {
- state->error = 1;
- osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
- "Unable to find first SELECT in query # %d", id ));
- return NULL;
- }
-
- // Get the SELECT list for the first SELECT
- SelectItem* col = query->select_list;
- if( !col ) {
- state->error = 1;
- osrfLogError( OSRF_LOG_MARK, sqlAddMsg( state,
- "First SELECT in query # %d has empty SELECT list", id ));
- return NULL;
- }
-
- jsonObject* col_list = jsonNewObjectType( JSON_ARRAY );
-
- // Traverse the list, adding an entry for each
- do {
- const char* alias = NULL;
- if( col->column_alias )
- alias = col->column_alias;
- else {
- Expression* expression = col->expression;
- if( expression && EXP_COLUMN == expression->type && expression->column_name )
- alias = expression->column_name;
- }
-
- jsonObjectPush( col_list, jsonNewObject( alias ) );
- col = col->next;
- } while( col );
-
- return col_list;
-}
-
-/**
@brief Push an IdNode onto a stack of IdNodes.
@param stack Pointer to the stack.
@param id Id of the new node.
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