Problem with copy

[WTDdallas]

I have written this code :

procedure AppendRecord(dsSource, dsTarget: tdataset);     // Append Record  and copy from one Dataset to another
var
    i: Integer;                                                               // Requires both Dataset to be open
begin
  dsTarget.append;                                                            // Append target

  with dsSource do
  begin
    for i := 0 to FieldCount-1 do                                             // For each field
      begin
       try
        dsTarget.fieldbyname(fields.FieldName).value := Fields.Value;   // copy Source.Value to Target(source.fieldname).Value
       finally
       end;
      end;
  end;

  dsTarget.post;                                                             // Post Target
end; 

I get invalid value,if the a date, crashes on empty date field.
How do i Precheck for valid value?

 How do i Fix that?

[Ñuño_Martínez]

Please: use [ code=pascal] [ /code] (the icon with a # over the smileys) to format your code snippets.  They'll be easier to read.

Also, "WITH" isn't very recommendable and you should use it only if you really need it (wich means almost never). It may introduce a lot of hard to track bugs.  And you don't need teh "TRY .. FINALLY .. END" block, as "FINALLY" is empty.

Since you're not telling to the DataSet what field are you using, it tries (and success) to assign all fields to the target, as "Value" is of type "VARIANT".  You should use property "asDateTime" (or "asString", or "asInteger", or ...) instead of "Value".

So:

Code: Pascal  [Select][+][-]

1. (* Append Record  and copy from one Dataset to another *)
2. PROCEDURE AppendRecord (dsSource, dsTarget:  TDataSet);
3. VAR
4.   i: INTEGER;
5. BEGIN
6.   dsTarget.Append;
7.   FOR i := 0 TO FieldCount-1 DO
8.     dsTarget.FieldByName (dsSource.Fields[i].FieldName).asDateTime :=
9.       dsSource.Fields[i].asDateTime;
10.   dsTarget.Post
11. END;  
12.  

[WTDdallas]

Please: use [ code=pascal] [ /code] (the icon with a # over the smileys) to format your code snippets.  They'll be easier to read.

Also, "WITH" isn't very recommendable and you should use it only if you really need it (wich means almost never). It may introduce a lot of hard to track bugs.  And you don't need teh "TRY .. FINALLY .. END" block, as "FINALLY" is empty.

Since you're not telling to the DataSet what field are you using, it tries (and success) to assign all fields to the target, as "Value" is of type "VARIANT".  You should use property "asDateTime" (or "asString", or "asInteger", or ...) instead of "Value".

So:

Code: Pascal  [Select][+][-]

1. (* Append Record  and copy from one Dataset to another *)
2. PROCEDURE AppendRecord (dsSource, dsTarget:  TDataSet);
3. VAR
4.   i: INTEGER;
5. BEGIN
6.   dsTarget.Append;
7.   FOR i := 0 TO FieldCount-1 DO
8.     dsTarget.FieldByName (dsSource.Fields[i].FieldName).asDateTime :=
9.       dsSource.Fields[i].asDateTime;
10.   dsTarget.Post
11. END;  
12.  

The Hold Idea is to setup a generic Append record, so you don't know which fields is what, and don't have to.

I was just needed a way to trap the error and skip to next field.

This worked until A non-date value was import into the dataset, which I fix on import, did prechecking there.

But I want to make a Smarter Append Record, So it can't crash, or at least skips field.

Sorry didn't know about code# button.

Code: Pascal  [Select][+][-]

1. [/
2. procedure AppendRecord(dsSource, dsTarget: tdataset);                         // Append Record  and copy from one Dataset to another
3. var
4.     i: Integer;                                                               // Requires both Dataset to be open
5. begin
6.   dsTarget.append;                                                            // Append target
7.  
8.   with dsSource do
9.   begin
10.     for i := 0 to FieldCount-1 do                                             // For each field
11.       begin
12.        try
13.         dsTarget.fieldbyname(fields[i].FieldName).value := Fields[i].Value;   // copy Source.Value to Target(source.fieldname).Value
14.        finally
15.        end;
16.       end;
17.   end;
18.  
19.   dsTarget.post;                                                             // Post Target
20. end;
21.  
22. procedure ReplaceRecord(dsSource, dsTarget: tdataset);                       // Copy Record from one Dataset to another over existing one
23. var
24.     i: Integer;                                                              // Requires both Dataset to be open
25. begin
26.   dsTarget.edit;                                                              // Append target
27.  
28.   with dsSource do
29.   begin
30.     for i := 0 to FieldCount-1 do                                             // For each field
31.       begin
32.         try
33.         dsTarget.fieldbyname(fields[i].FieldName).value := Fields[i].Value;   // copy Source.Value to Target(source.fieldname).Value
34.  
35.         finally
36.         end;
37.       end;
38.   end;
39.  
40.   dsTarget.post;                                                              // Post Target
41. end;
42.      
43. ]