JSON question: I'm wanting to use Delphi's latest JSON Builder to create a JSON expression that is structured like this:

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JSON question: I'm wanting to use Delphi's latest JSON Builder to create a JSON expression that is structured like this:

NumStartMethods: integer
StartMethodUsed: integer
StartMethods:
Method1
param1 = something1
param2 = something2
Method2
param1 = something3
param2 = something4
param3 = something5

So we have two pairs, and an array of objects.

But I can't figure out how to get an array of objects to work!

{
"Bookmark": {
"NumStartMethods": 2,
"StartMethodUsed": 1,
"StartMethods": [
"StartMethod-1": {
"aID": "",
"aName": "foo"
},
"StartMethod-2": {
"aID": "xyz",
"aName": "bar"
"aFlag": false
}
]
}
}

This doesn't work.

Changing the square brackets to curly brackets works, but then StartMethods is just an object that contains objects, which is not what I want.

Builder
.BeginObject
.BeginObject('Bookmark')
.Add('NumStartMethods', 1)
.Add('StartMethodCalled', 1)
//.BeginArray('StartMethods')
.BeginObject('StartMethod-1')
.Add('aID', aID )
.Add('aName', aName)
.EndObject
.BeginObject('StartMethod-2')
.Add('aID', 'xyz' )
.Add('aName', aName)
.Add('aLoop', False )
.EndObject
//.EndArray
.EndObject
.EndObject;


I want to be able to access StartMethods[ StartMethodUsed ] to figure out which set of parameters are needed.

Maybe I'm just thinking about this wrong?

Comments

  1. Lars FosdalAugust 13, 2018 at 12:37 AM

    jsonlint.com - The JSON Validator can show you where the Json doesn't "add up".

    A list has to be a list of either base types (int, string, etc), or a list of objects. I would do it like this:

    {
    "Bookmark": {
    "NumStartMethods": 2,
    "StartMethodUsed": 1,
    "StartMethods": [{
    "MethodName": "StartMethod1",
    "aID": "",
    "aName": "foo"
    },
    {
    "MethodName": "StartMethod2",
    "aID": "xyz",
    "aName": "bar",
    "aFlag": false
    }
    ]
    }
    }

    I'd also consider changing the StartMethodUsed to refer to MethodName, so that you don't get into list reordering situations.

    ReplyDelete
  2. Lars FosdalAugust 13, 2018 at 1:43 AM

    Also note that dealing with polymorphic object lists usually require a bit of "manual intervention" with regards to the built in Delphi methods.

    ReplyDelete
  3. David SchwartzAugust 13, 2018 at 1:51 AM

    Thanks. Unfortunately, the start method names are the same (overloaded). But in adding the code that generates this JSON data, I realized this isn't the correct approach anyway. I know some of these forms have multiple start methods that take different parameter lists. I'm just not sure yet how to figure out what to throw at them. But it's a great use of JSON data structures!

    ReplyDelete

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