On 9/25/18 8:03 PM, mohamed hamza wrote:
> I believed that filter has been set somewhere by a module of lib and set
> filtred to true also. I find that I am wrong ?
>
AFAIK TSQLQuery.Filter will be added to TSQLQuery.SQL text:
"
Function TSQLQuery.AddFilter(SQLstr : msestring) : msestring;
begin
if FWhereStartPos = 0 then
SQLstr := SQLstr + ' where (' + msestring(Filter) + ')'
else if FWhereStopPos > 0 then
system.insert(' and ('+msestring(Filter)+') ',SQLstr,FWhereStopPos+1)
else
system.insert(' where ('+msestring(Filter)+') ',SQLstr,FWhereStartPos);
Result := SQLstr;
end;
"
which filters the result set on server if "Filtered" is true. I never
used that functionality. The dbfilter2 demo uses "onfilterrecord" in
order to filter records locally:
"
procedure tmainfo.onfilterrecordev(dataset: tdataset; var accept: boolean);
//slow! in order to improve performance use
//local copies of the filter values, don't use variants
begin
accept:= tmsebufdataset(dataset).checkfiltervalues();
end;
"
which checks the set filter values:
"
function tmsebufdataset.checkfiltervalue(const afield: tfield;
const akind: filtereditkindty = fek_filter;
const acaseinsensitive: boolean = true): boolean;
var
i1: int32;
p1: precheaderty;
v1: variant;
b1: boolean;
begin
if afield.dataset <> self then begin
databaseerror('Invalid field "'+afield.name+'"',self);
end;
result:= true; //default
i1:= afield.fieldno-1;
p1:= @ffilterbuffer[akind]^.header;
if i1 >= 0 then begin //data field
b1:= not getfieldflag(p1^.fielddata.nullmask,i1);
end
else begin //calc field
i1:= -2 - i1;
if i1 >= 0 then begin //calc field
b1:= not getfieldflag(pointer(p1)+frecordsize,i1);
end
else begin
exit;//invalid field
end;
end;
if not b1 then begin //filter not null
b1:= afield.isnull;
v1:= fieldfiltervalue(afield,akind);
if afield.datatype = ftstring then begin
if acaseinsensitive then begin
i1:= unicodecomparetext(afield.asmsestring,unicodestring(v1));
end
else begin
i1:= unicodecomparestr(afield.asmsestring,unicodestring(v1));
end;
case akind of
fek_filtermin: begin
result:= not b1 and (i1 >= 0);
end;
fek_filter: begin
result:= i1 = 0;
end;
fek_filtermax: begin
result:= b1 or (i1 <= 0);
end;
end;
end
else begin
case akind of
fek_filtermin: begin
result:= not b1 and (afield.value >= v1);
end;
fek_filter: begin
result:= afield.value = v1;
end;
fek_filtermax: begin
result:= b1 or (afield.value <= v1);
end;
end;
end;
end;
end;
function tmsebufdataset.checkfiltervalues(const afield: tfield;
const acaseinsensitive: boolean = true): boolean;
//calls checkfiltervalue() for all filtereditkinds
var
f1: filtereditkindty;
begin
for f1:= low(f1) to fek_filtermax do begin
result:= checkfiltervalue(afield,f1,acaseinsensitive);
if not result then begin
break;
end;
end;
end;
function tmsebufdataset.checkfiltervalues(
const acaseinsensitive: boolean = true): boolean;
//calls checkfiltervalue() for all fields and all filtereditkinds
var
i1: int32;
begin
result:= true;
for i1:= 0 to fields.count-1 do begin
result:= checkfiltervalues(fields[i1],acaseinsensitive);
if not result then begin
break;
end;
end;
end;
"
> Concerning the second point I can not see why dbfilter2 will run normally
> with bdo_local option and a database will not ?
>
With the same fields and field types?
> I used the same event manager than dbfilter2. Are there other methods to
> manage filter ?
>
There can be any code executed in onfilterrecord in order to define if a
record should be visible.
Martin
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