Django combine two json objects to form a new array

Question

I have two json objects as follow

Id:1

 {"points":[{"x":109,"y":286,"r":1,"color":"black"},{"x":108,"y":285,"r":1,"color":"black"},{"x":106,"y":282,"r":1,"color":"black"},{"x":103,"y":276,"r":1,"color":"black"},],"lines":[{"x1":109,"y1":286,"x2":108,"y2":285,"strokeWidth":"2","strokeColor":"black"},{"x1":108,"y1":285,"x2":106,"y2":282,"strokeWidth":"2","strokeColor":"black"},{"x1":106,"y1":282,"x2":103,"y2":276,"strokeWidth":"2","strokeColor":"black"}]}

Id-2

{"points":[{"x":524,"y":343,"r":1,"color":"black"},{"x":523,"y":342,"r":1,"color":"black"},{"x":521,"y":339,"r":1,"color":"black"},{"x":520,"y":334,"r":1,"color":"black"},{"x":514,"y":319,"r":1,"color":"black"}],"lines":[{"x1":524,"y1":343,"x2":523,"y2":342,"strokeWidth":"2","strokeColor":"black"},{"x1":523,"y1":342,"x2":521,"y2":339,"strokeWidth":"2","strokeColor":"black"},{"x1":521,"y1":339,"x2":520,"y2":334,"strokeWidth":"2","strokeColor":"black"},{"x1":520,"y1":334,"x2":514,"y2":319,"strokeWidth":"2","strokeColor":"black"}]}

I am trying to merge these two data onto a canvas I am able to retrieve a single file but combining them i am not able to do

def loadDrawing(request):
    """ Function to load the drawing with drawingID if it exists."""
    try:
        # Getting JSON object string of saved drawing.
        drawingJSONData = Drawing.objects.get(id = 1).drawingJSONText

        # drawingJSONData1 = Drawing.objects.get(id=1).drawingJSONText
       # drawingJSONData2 = Drawing.objects.get(id=2).drawingJSONText

        # Seding context with appropriate information
        context = {
            "loadIntoJavascript" : True,
            "JSONData" : drawingJSONData

        }
        # Editing response headers and returning the same
        response = modifiedResponseHeaders(render(request, 'MainCanvas/index.html', context))
        return response

My model in django

class Drawing(models.Model):
    drawingJSONText = models.TextField(null = True)

My .js file to load the drawing and parsing it from server to JSON object and pushing the loaded points into an array

 // Checking if the drawing to be loaded exists
    if (document.getElementById('JSONLoadData') != null)
    {

        // Parsing the loaded drawing from server to a JSON Object
        var loadedData = JSON.parse(JSONLoadData.value)

        // Iterating through all the points in the loaded drawing
        for(let i = 0; i < loadedData['points'].length; i++)
        {
            // Saving the point and drawing the same in the svg canvas
            const point = svg.append('circle')
                             .attr('cx', loadedData['points'][i]['x'])
                             .attr('cy', loadedData['points'][i]['y'])
                             .attr('r', loadedData['points'][i]['r'])
                             .style('fill', loadedData['points'][i]['color']);

            // Pushing the point inside points array
            points.push(point);
        }

        // Iterating through all the lines in the loaded drawing
        for(let i = 0; i < loadedData['lines'].length; i++)
        {
            // Saving the line and drawing the same in the svg canvas
            const line = svg.append('line')
                            .attr('x1', loadedData['lines'][i]['x1'])
                            .attr('y1', loadedData['lines'][i]['y1'])
                            .attr('x2', loadedData['lines'][i]['x2'])
                            .attr('y2', loadedData['lines'][i]['y2'])
                            .attr('stroke-width', loadedData['lines'][i]['strokeWidth'])
                            .style('stroke', loadedData['lines'][i]['strokeColor']);

            // Pushing the line inside lines array
            lines.push(line);
        }

    }

});

Edited : If my model is as follows

class Drawing(models.Model):
    drawingJSONText = models.TextField(null=True)
    project = models.CharField(max_length=250)

How can i filter data based on project Lets say i have three datasets

1st one contains project = a
2nd one contains project = b
3rd one contains project = a
4th one contains project = a

How can i add datapoints like above by filtering data Drawing.objects.filter(project=a) then based on the queryset i have three data points and corresponding data are plotted on canvas as above

AMG · Accepted Answer · 2021-03-08 12:24:46Z

1

I'm not entirely sure this is what you want, but are you trying to combine id-1 and id-2? If I think I understand what you are trying to do, will using the + operator work for you in this case?

drawingJSONData1 = json.loads(Drawing.objects.get(id=1).drawingJSONText)
drawingJSONData2 = json.loads(Drawing.objects.get(id=1).drawingJSONText)

drawingJSONData = dict()
drawingJSONData["points"] = drawingJSONData1["points"]+drawingJSONData1["points"]
drawingJSONData["lines"] = drawingJSONData2["lines"]+drawingJSONData2["lines"]

With your example above, you'd end up with:

{'points': [{'x': 109, 'y': 286, 'r': 1, 'color': 'black'},
  {'x': 108, 'y': 285, 'r': 1, 'color': 'black'},
  {'x': 106, 'y': 282, 'r': 1, 'color': 'black'},
  {'x': 103, 'y': 276, 'r': 1, 'color': 'black'},
  {'x': 524, 'y': 343, 'r': 1, 'color': 'black'},
  {'x': 523, 'y': 342, 'r': 1, 'color': 'black'},
  {'x': 521, 'y': 339, 'r': 1, 'color': 'black'},
  {'x': 520, 'y': 334, 'r': 1, 'color': 'black'},
  {'x': 514, 'y': 319, 'r': 1, 'color': 'black'}],
 'lines': [{'x1': 109,
   'y1': 286,
   'x2': 108,
   'y2': 285,
   'strokeWidth': '2',
   'strokeColor': 'black'},
  {'x1': 108,
   'y1': 285,
   'x2': 106,
   'y2': 282,
   'strokeWidth': '2',
   'strokeColor': 'black'},
  {'x1': 106,
   'y1': 282,
   'x2': 103,
   'y2': 276,
   'strokeWidth': '2',
   'strokeColor': 'black'},
  {'x1': 524,
   'y1': 343,
   'x2': 523,
   'y2': 342,
   'strokeWidth': '2',
   'strokeColor': 'black'},
  {'x1': 523,
   'y1': 342,
   'x2': 521,
   'y2': 339,
   'strokeWidth': '2',
   'strokeColor': 'black'},
  {'x1': 521,
   'y1': 339,
   'x2': 520,
   'y2': 334,
   'strokeWidth': '2',
   'strokeColor': 'black'},
  {'x1': 520,
   'y1': 334,
   'x2': 514,
   'y2': 319,
   'strokeWidth': '2',
   'strokeColor': 'black'}]}

EDIT: added the gets wrapped in json.loads to convert string to Python object as I don't know what kind of field that is and given the error being seen.

edited Mar 8, 2021 at 12:24

answered Mar 8, 2021 at 3:48

AMG

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9 Comments

Raviteja Reddy Over a year ago

I get a type error "string indices must be integers"

AMG Over a year ago

I've edited answer a bit. You may have to convert the strings you have in those fields to a python object for it to work properly. Edit your question to show what your Drawing model looks like.

Raviteja Reddy Over a year ago

I dont get an error now , but i get a blank page no coordinates are loaded onto the canvas.

AMG Over a year ago

guessing you need to convert back to a string? in your context try "JSONData" : json.dumps(drawingJSONData),

Raviteja Reddy Over a year ago

extension to above , if lets say i have to filter the data based on another data in model then does the '+' work.Edited model

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