Reply to: Create empty typed JSON object?

[NickFitz]

Why does it matter?

Because the things such as constraints aren't anything to do with JSON: they're added on by the platform you're using. JSON itself is so lightweight that the entire specification fits into the sidebar of this page: JSON

[doodab]

Can you have a separate data structure with a single row of nulls you use as a template?

[mudskipper]

Owing to the constraints of the BPM framework, this can only be done on the client side. So I need to effectively keep a client side copy of the DataTable.

Is this really the case? Can't you use callbacks or similar to save a server side data structure in a session variable?

[fullyautomatix]

JSON is javascript and javascript is prototype based and supports dynamic typing. Next !

[suityou01]

And he's back databinding to nested arrays........

No, no I'm not. The grids are bound to Datatables.

Did you read the thread at all.

[DimPrawn]

And he's back databinding to nested arrays........

[proggy]

Now now.

I'm busy so just scanned it, missed the part you mentioned this is a web app. I am so sorry. Because of that I will only charge half a days rate.

[suityou01]

Because he doesn't understand what you're asking

Now now.

[proggy]

Why does it matter?

Sorry I read grids on a form and thought it was some windows client, my mistake sorry. I'm out of ideas I would do as jmo1 suggests and ask on StackOverflow.

[Spacecadet]

Why does it matter?

Because he doesn't understand what you're asking

[suityou01]

How can I create an empty typed JSON object in javascript?

Owing to the constraints of the BPM framework, this can only be done on the client side. So I need to effectively keep a client side copy of the DataTable.

What are you using here? .NET ,JAVA, Python ,LISP?

Why does it matter?

[proggy]

OK. The problem domain is this :

Client wants Grids on a form. The Grids represent hierarchical data. It must be possible to manipulate the Grids (add and delete parent and child rows) without persisting any data to the database tables until the form is submitted.

So this means I have to maintain a DataTable per grid in memory.

There is some GUI logic that says if the "Count" column of the Parent row does not have the correct number of child records then prevent form submission and display some client side validation.

Owing to the constraints of the BPM framework, this can only be done on the client side. So I need to effectively keep a client side copy of the DataTable.

JSON looked like a good approach. If you have to create JSON objects prepopulated with garbage then I agree, they are not what I need.

What would be a better client side technology? I wanted to stay away from basic arrays. JSON had lots of cool stuff baked in to decorate the columns with constraints which I liked.

What are you using here? .NET ,JAVA, Python ,LISP?

[suityou01]

You can't, perhaps JSON isn't the most appropriate notation for your problem?

OK. The problem domain is this :

Client wants Grids on a form. The Grids represent hierarchical data. It must be possible to manipulate the Grids (add and delete parent and child rows) without persisting any data to the database tables until the form is submitted.

So this means I have to maintain a DataTable per grid in memory.

There is some GUI logic that says if the "Count" column of the Parent row does not have the correct number of child records then prevent form submission and display some client side validation.

Owing to the constraints of the BPM framework, this can only be done on the client side. So I need to effectively keep a client side copy of the DataTable.

JSON looked like a good approach. If you have to create JSON objects prepopulated with garbage then I agree, they are not what I need.

What would be a better client side technology? I wanted to stay away from basic arrays. JSON had lots of cool stuff baked in to decorate the columns with constraints which I liked.

[proggy]

OK, I'm happy with the typing aspect. The typing aspects don't bother me at all. It is purely semantics as far as this problem is concerned.

What I am after is an empty JSON object, that defines the dimensions of the "array".

If you thought of the JSON object as a humble database table, I can define the columns but not have any rows. That is what I need. A JSON object with only columns.

You can't, perhaps JSON isn't the most appropriate notation for your problem?

[suityou01]

I don't think you can mate, you can throw any old stuff into a Json array.

OK, I'm happy with the typing aspect. The typing aspects don't bother me at all. It is purely semantics as far as this problem is concerned.

What I am after is an empty JSON object, that defines the dimensions of the "array".

If you thought of the JSON object as a humble database table, I can define the columns but not have any rows. That is what I need. A JSON object with only columns.