ogrmysqltablelayer.cpp

来自「GIS系统支持库Geospatial Data Abstraction Libr」· C++ 代码 · 共 562 行 · 第 1/2 页

    char *pszFields = BuildFields();

    pszQueryStatement = (char *) 
        CPLMalloc(strlen(pszFields)+strlen(pszWHERE)
                  +strlen(poFeatureDefn->GetName()) + 40);
    sprintf( pszQueryStatement,
             "SELECT %s FROM %s %s", 
             pszFields, poFeatureDefn->GetName(), pszWHERE );
    
    CPLFree( pszFields );
}

/************************************************************************/
/*                            ResetReading()                            */
/************************************************************************/

void OGRMySQLTableLayer::ResetReading()

{
    BuildFullQueryStatement();

    OGRMySQLLayer::ResetReading();
}

/************************************************************************/
/*                            BuildFields()                             */
/*                                                                      */
/*      Build list of fields to fetch, performing any required          */
/*      transformations (such as on geometry).                          */
/************************************************************************/

char *OGRMySQLTableLayer::BuildFields()

{
    int         i, nSize;
    char        *pszFieldList;

    nSize = 25;
    if( pszGeomColumn )
        nSize += strlen(pszGeomColumn);

    if( bHasFid )
        nSize += strlen(pszFIDColumn);

    for( i = 0; i < poFeatureDefn->GetFieldCount(); i++ )
        nSize += strlen(poFeatureDefn->GetFieldDefn(i)->GetNameRef()) + 4;

    pszFieldList = (char *) CPLMalloc(nSize);
    pszFieldList[0] = '\0';

    if( bHasFid && poFeatureDefn->GetFieldIndex( pszFIDColumn ) == -1 )
        sprintf( pszFieldList, "%s", pszFIDColumn );

    if( pszGeomColumn )
    {
        if( strlen(pszFieldList) > 0 )
            strcat( pszFieldList, ", " );

        sprintf( pszFieldList+strlen(pszFieldList), 
                 "%s", pszGeomColumn );
    }

    for( i = 0; i < poFeatureDefn->GetFieldCount(); i++ )
    {
        const char *pszName = poFeatureDefn->GetFieldDefn(i)->GetNameRef();

        if( strlen(pszFieldList) > 0 )
            strcat( pszFieldList, ", " );

        strcat( pszFieldList, pszName );
    }

    CPLAssert( (int) strlen(pszFieldList) < nSize );

    return pszFieldList;
}

/************************************************************************/
/*                         SetAttributeFilter()                         */
/************************************************************************/

OGRErr OGRMySQLTableLayer::SetAttributeFilter( const char *pszQuery )

{
    CPLFree( this->pszQuery );

    if( pszQuery == NULL || strlen(pszQuery) == 0 )
        this->pszQuery = NULL;
    else
        this->pszQuery = CPLStrdup( pszQuery );

    BuildWhere();

    ResetReading();

    return OGRERR_NONE;
}

/************************************************************************/
/*                           TestCapability()                           */
/************************************************************************/

int OGRMySQLTableLayer::TestCapability( const char * pszCap )

{
    if( EQUAL(pszCap,OLCRandomRead) )
        return bHasFid;

    else if( EQUAL(pszCap,OLCFastFeatureCount) )
        return TRUE;

    else 
        return OGRMySQLLayer::TestCapability( pszCap );
}

/************************************************************************/
/*                             GetFeature()                             */
/************************************************************************/

OGRFeature *OGRMySQLTableLayer::GetFeature( long nFeatureId )

{
    if( pszFIDColumn == NULL )
        return OGRMySQLLayer::GetFeature( nFeatureId );

/* -------------------------------------------------------------------- */
/*      Discard any existing resultset.                                 */
/* -------------------------------------------------------------------- */
    poDS->InterruptLongResult();

/* -------------------------------------------------------------------- */
/*      Prepare query command that will just fetch the one record of    */
/*      interest.                                                       */
/* -------------------------------------------------------------------- */
    char        *pszFieldList = BuildFields();
    char        *pszCommand = (char *) CPLMalloc(strlen(pszFieldList)+2000);

    sprintf( pszCommand, 
             "SELECT %s FROM %s WHERE %s = %ld", 
             pszFieldList, poFeatureDefn->GetName(), pszFIDColumn, 
             nFeatureId );
    CPLFree( pszFieldList );

/* -------------------------------------------------------------------- */
/*      Issue the command.                                              */
/* -------------------------------------------------------------------- */
    if( mysql_query( poDS->GetConn(), pszCommand ) )
    {
        poDS->ReportError( pszCommand );
        return NULL;
    }
    CPLFree( pszCommand );

    hResultSet = mysql_store_result( poDS->GetConn() );
    if( hResultSet == NULL )
    {
        poDS->ReportError( "mysql_store_result() failed on query." );
        return NULL;
    }

/* -------------------------------------------------------------------- */
/*      Fetch the result record.                                        */
/* -------------------------------------------------------------------- */
    char **papszRow;

    papszRow = mysql_fetch_row( hResultSet );
    if( papszRow == NULL )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Transform into a feature.                                       */
/* -------------------------------------------------------------------- */
    iNextShapeId = nFeatureId;

    OGRFeature *poFeature = RecordToFeature( papszRow );

    iNextShapeId = 0;

/* -------------------------------------------------------------------- */
/*      Cleanup                                                         */
/* -------------------------------------------------------------------- */
    mysql_free_result( hResultSet );

    return poFeature;
}

/************************************************************************/
/*                          GetFeatureCount()                           */
/*                                                                      */
/*      If a spatial filter is in effect, we turn control over to       */
/*      the generic counter.  Otherwise we return the total count.      */
/*      Eventually we should consider implementing a more efficient     */
/*      way of counting features matching a spatial query.              */
/************************************************************************/

int OGRMySQLTableLayer::GetFeatureCount( int bForce )

{
/* -------------------------------------------------------------------- */
/*      Ensure any active long result is interrupted.                   */
/* -------------------------------------------------------------------- */
    poDS->InterruptLongResult();
    
/* -------------------------------------------------------------------- */
/*      Issue the appropriate select command.                           */
/* -------------------------------------------------------------------- */
    MYSQL_RES    *hResult;
    const char         *pszCommand;

    pszCommand = CPLSPrintf( "SELECT COUNT(*) FROM %s %s", 
                             poFeatureDefn->GetName(), pszWHERE );

    if( mysql_query( poDS->GetConn(), pszCommand ) )
    {
        poDS->ReportError( pszCommand );
        return FALSE;
    }

    hResult = mysql_store_result( poDS->GetConn() );
    if( hResult == NULL )
    {
        poDS->ReportError( "mysql_store_result() failed on SELECT COUNT(*)." );
        return FALSE;
    }
    
/* -------------------------------------------------------------------- */
/*      Capture the result.                                             */
/* -------------------------------------------------------------------- */
    char **papszRow = mysql_fetch_row( hResult );
    int nCount = 0;

    if( papszRow != NULL && papszRow[0] != NULL )
        nCount = atoi(papszRow[0]);

    mysql_free_result( hResult );
    
    return nCount;
}

/************************************************************************/
/*                           GetSpatialRef()                            */
/*                                                                      */
/*      We override this to try and fetch the table SRID from the       */
/*      geometry_columns table if the srsid is -2 (meaning we           */
/*      haven't yet even looked for it).                                */
/************************************************************************/

OGRSpatialReference *OGRMySQLTableLayer::GetSpatialRef()

{
#ifdef notdef
    if( nSRSId == -2 )
    {
        PGconn          *hPGConn = poDS->GetPGConn();
        PGresult        *hResult;
        char            szCommand[1024];

        nSRSId = -1;

        poDS->SoftStartTransaction();

        sprintf( szCommand, 
                 "SELECT srid FROM geometry_columns "
                 "WHERE f_table_name = '%s'",
                 poFeatureDefn->GetName() );
        hResult = PQexec(hPGConn, szCommand );

        if( hResult 
            && PQresultStatus(hResult) == PGRES_TUPLES_OK 
            && PQntuples(hResult) == 1 )
        {
            nSRSId = atoi(PQgetvalue(hResult,0,0));
        }
        PQclear( hResult );

        poDS->SoftCommit();
    }
#endif
    return OGRMySQLLayer::GetSpatialRef();
}