Delphi - TClientDataSet - storing filter and indexes definitions

Question

I need some help concerning TClientDataSet since after doing extensive research, I'm still confused about some features.

From what I so far understand, saving the TClientDataSet structure to a file, preserves only the FieldDefs. All other definitions such as filters and indexes are lost. So, I must recreate them after openning the DataSet, in order to that definitions take place.

I infere from this, that, if I want to store those definitions in disk (so they will available to the application as a whole and not only for a specific form), I must maintain a separate DataSet. Then, at runtime, I can recreate all definitions from that DataSet.

My question is: is there any other mechanism to store those definitions, other than the one mentioned above? A TDataSetProvider can do the trick?

I appologize for my ignorance and appreciate any enlightment about the subject.

Thanks in advance.

Answer 1

Yes, there are many possibilities to do what you want.

But, TDataSetProvider is not one of them.

It is possible to use:

• 1 TRegistry
• 2 TIniFiles
• 3 Persist it in database (not a good approach)
• 4 Another DataSet, as you mentioned.

Pick the easier and most realiable for you.
TIniFile is very often used to save definitions in many scenarios.

Answer 2

When you save ClientDataSet it saves data structure, data, index definitions, parameters, delta-data etc. It saves only one filter definition though.

You can also save indesies and filters in Delphi code.

As mentioned Registry and IniFiles are possibilities too.