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Code: Select all

function TZAbstractDatabaseMetadata.GetProcedures(const Catalog, SchemaPattern,
  ProcedureNamePattern: string): IZResultSet;
var
  Key: string;
begin
  Key := Format('get-procedures:%s:%s:%s',
    [Catalog, SchemaPattern, ProcedureNamePattern]);

  Result := GetResultSetFromCache(Key);
  if Result = nil then
  begin
    Result := RetrieveProceduresMetaData(Catalog, SchemaPattern,ProcedureNamePattern);
    AddResultSetToCache(Key, Result);
  end;
end;

function TZAbstractDatabaseMetadata.RetrieveProceduresMetaData(const Catalog, SchemaPattern,
  ProcedureNamePattern: string): IZResultSet;
begin
    Result := ConstructVirtualResultSet(ProceduresColumnsDynArray);
end;

function TZAdoDatabaseMetadata.RetrieveProceduresMetaData(const Catalog, SchemaPattern,
  ProcedureNamePattern: string): IZResultSet;
var
  AdoRecordSet: ZPlainAdo.RecordSet;
begin
    Result := ConstructVirtualResultSet(ProceduresColumnsDynArray);

    AdoRecordSet := AdoOpenSchema(adSchemaProcedures,
      [Catalog, SchemaPattern, ProcedureNamePattern, '']);
    if Assigned(AdoRecordSet) then
    begin
      with TZAdoResultSet.Create(GetStatement, '', AdoRecordSet) do
      begin
        while Next do
        begin
          Result.MoveToInsertRow;
          Result.UpdateStringByName('PROCEDURE_CAT',
            GetStringByName('PROCEDURE_CATALOG'));
          Result.UpdateStringByName('PROCEDURE_SCHEM',
            GetStringByName('PROCEDURE_SCHEMA'));
          Result.UpdateStringByName('PROCEDURE_NAME',
            GetStringByName('PROCEDURE_NAME'));
          Result.UpdateStringByName('REMARKS',
            GetStringByName('DESCRIPTION'));
          Result.UpdateShortByName('PROCEDURE_TYPE',
            GetShortByName('PROCEDURE_TYPE') - 1);
          Result.InsertRow;
        end;
        Close;
        Free;
      end;
    end;
end;

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// public code%u3a
type
  TDBMetadataEntry = %u28dbmeTables, dbmeColumns, ....%u29;
  TDBMetadataEntries = set of TDBMetadataEntry;

// private code%u3a
const
  DBMetadataKey = array %u5bTDBMetadataEntry%u5d of ShortString = %u28
    'get-tables',     // dbmeTables
    'get-columns',  // dbmeColumns
    ....
  %u29;

// TZAbstractDatabaseMetadata code%u3a

procedure TZAbstractDatabaseMetadata.ClearCache%u28const Keys%u3a TDBMetadataEntries%u29
begin
  ....
end;

function TZAbstractDatabaseMetadata.GetProcedures%u28const Catalog, SchemaPattern,
  ProcedureNamePattern%u3a string%u29%u3a IZResultSet;
var
  Key%u3a string;
begin
  Key %u3a= DBMetadataKey%u5bdbmeProcedures%u5d;

  ...
end;

Code: Select all

function <class>.Getxxxx(<params>): IZResultSet;
var
  Key: string;
begin
  Key := GetxxxxCacheKey(<params>);

  Result := GetResultSetFromCache(Key);
  if Result = nil then
  begin
    Result := ConstructVirtualResultSet(xxxxColumnsDynArray);
    <fill Result, optionally using the params>
    AddResultSetToCache(Key, Result);
  end;
end;

Code: Select all

function TZAbstractDatabaseMetadata.GetCachedMetadata(const Key: string; const ColumnsDefs: TZMetadataColumnDefs; out ResultSet: IZResultSet): Boolean;
begin
  ResultSet := GetResultSetFromCache(Key);
  Result := Assigned(ResultSet);
  if (not Result) then
  begin
    ResultSet := ConstructVirtualResultSet(ColumnsDefs);
    AddResultSetToCache(Key, ResultSet);
  end;
end;


function TZAbstractDatabaseMetadata.GetProcedures(const Catalog: string;
  const SchemaPattern: string; const ProcedureNamePattern: string): IZResultSet;
var
  Key: string;
begin
  Key := GetProceduresCacheKey(Catalog, SchemaPattern, ProcedureNamePattern);

  if (not GetCahcedMetadata(Key, ProceduresColumnsDynArray, Result)) then
    GetProceduresMetadata(Catalog, SchemaPattern, ProcedureNamePattern, Result);
end;


procedure <descendant-class>.GetProceduresMetadata(const Catalog: string;
  const SchemaPattern: string; const ProcedureNamePattern: string; Result: IZResultSet);
begin
  // fill the result set
end;

Code: Select all

function <descendant-class>.Getxxxx(<params>): IZResultSet;
begin
  Result := inherited;
  <fill Result>
end;

Code: Select all

// current structure:
function <class>.Getxxxx(<params>): IZResultSet;
var
  Key: string;
begin
  Key := GetxxxxCacheKey(<params>);

  Result := GetResultSetFromCache(Key);
  if Result = nil then
  begin
    Result := ConstructVirtualResultSet(xxxxColumnsDynArray);
    <fill Result, optionally using the params>
    AddResultSetToCache(Key, Result);
  end;
end;


// rearanged structure:
function <class>.Getxxxx(<params>): IZResultSet;
var
  Key: string;
begin
  Key := GetxxxxCacheKey(<params>);

  Result := GetResultSetFromCache(Key);
  if Result = nil then
  begin
    Result := ConstructVirtualResultSet(xxxxColumnsDynArray);
    AddResultSetToCache(Key, Result);
    <fill Result, optionally using the params> // notice that this moved to the end
  end;
end;


// final structure:
function <class>.Getxxxx(<params>): IZResultSet;
var
  Key: string;
begin
  Key := GetxxxxCacheKey(<params>);

  <call delegate to handle the cache. delegate returns a result-set and a boolean flag stating if the result set is new or not>

  <if the result-set is new, fill it, optionally using the params>
end;