Nested loop in birt report
I am using Eclipse Birt to generate a report from a JSON file.
My JSON file looks like this:
{
"cells":[
{
"type":"basic.Sensor",
"custom":{
"identifier":[
{
"name":"Name1",
"URI":"Value1"
},
{
"name":"Name4",
"URI":"Value4"
}
],
"classifier":[
{
"name":"Name2",
"URI":"Value2"
}
],
"output":[
{
"name":"Name3",
"URI":"Value3"
}
],
},
"image":{
"width":50,
"height":50,
"xlink:href":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAIAAAACACAYAAADDPmHLAAAABHNCSVQICAgIfAhkiAAAAAlwSFlzAABEJAAARCQBQGfEVAAAABl0RVh0U29mdHdhcmUAd3Vi8f+k/EREURQtsda2Or/+nFLqP6T5Ecdi0aJFL85msz2Qxyf4JIumMAx/ClmWt23GmL1kO54CXANAVH+WiN4Sx7EoNVkU3Z41BDHMeXAxjvOxNr7RJjzHX7S/jAflwBxkJr/RwiOpWZ883Nzd+Wpld7tkBr/SJr7ZHZbHZeuVweSnPfniocMAWYwcGBafH0OoPamFGAaY4ZBZjmmFGAaY4ZBZjmmFGAaY4ZBZjmmFGAaY7/B94QnX08zxKLAAAAAElFTkSuQmCC"
}
}
},
{
"type":"basic.Sensor",
"custom":{
"identifier":[
{
"name":"Name1",
"URI":"Value1"
},
{
"name":"Name4",
"URI":"Value4"
}
],
"classifier":[
{
"name":"Name2",
"URI":"Value2"
}
],
"output":[
{
"name":"Name3",
"URI":"Value3"
}
],
},
"image":{
"width":50,
"height":50,
"xlink:href":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAgAAAAIACAYAAAD0eNT6AAAACXBIWXMAAAsTAAALEwEAmpwYAAAKT2lDQ1BQaG90b3Nob3AgSUNDIHByb2ZpbGUAAHjanVNnVFPpFj333vRCS4iAlEtvUhUIIFJCi4AUkSYqIQkQSoghodkVUcERRUUEG8igiAOOjoCMFVEsDIoK2AfkIaKOg6OIisr74Xuja9igAQAAAgAIoAEAAAIACKABAAACAAigAQAAAgAIoAEAAAIACKABAAACAAigAQAAAgAIoAEAAAIADqhvprADeSsau00l5NAAAAAElFTkSuQmCC"
}
}
},
{
"type":"basic.Platform",
"custom":{
"identifier":[
{
"name":"Name1",
"URI":"Value1"
}
],
"classifier":[
{
"name":"Name2",
"URI":"Value2"
}
],
"output":[
{
"name":"Name3",
"URI":"Value3"
}
],
"image":{
"width":50,
"height":50,
"xlink:href":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAQAAAA6TH0jqtg6U8EsCdnm3SpevSK7Pb85xABEMBuLAn2hxjRve7SFzYEaB/HhytLQ4ABRwCWBPvBKnRk6U8EkBeOD9f7iwAGHAGEYEmwDxLvzNKfCCDP8NGLQd3lY7D0JwI4kmlwfHhX6dTSXxsRAAHsWR7aUjc7uM5Wg=="
}
}
}
]
}
I have 3 cells and each one contains 1 Image 1 Title 1 Type and 3 Tables, this is what I have done so far: 
what I am trying to do is a nested loop, I want to have for each object (cell) in my JSON a paragraph numbered like this:
- 2.x Component cell name:
- Picture
- Output table
- ID table
- Classifier table
To do this, I need to iterate over each cell and then repeat on each table. Output, id and classifier, and I don't know how to do this, nested loop. as a List that represents the number of cells that contains 3 tables, one image, one name.
** Edit: ** this is a public method for the dataset
// Grab the JSON file and place it in a string
fisTargetFile = new FileInputStream(new File("C:/Users/Sample Reports/moe.json"));
input = IOUtils.toString(fisTargetFile, "UTF-8");
// Store the contents in a variable
jsonData = input;
// Convert the String to a JSON object
myJSONObject = eval( '(' + jsonData + ' )' );
// Get the length of the object
len = myJSONObject.cells.length;
// Counter
count = 0;
Fetch method:
if(count < len) {
var name = myJSONObject.cells[count].attrs.text["text"];
var type = myJSONObject.cells[count].type;
var icon =myJSONObject.cells[count].attrs.image["xlink:href"];
icon = icon.split(",");
icon= icon[1];
imageDataBytes = icon;
row["name"] = name;
row["type"] = type;
row["icon"] = Base64ToBlob.toBytes(icon);
Logger.getAnonymousLogger().info( row["icon"]);
count++;
return true;
}
return false;
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You want to use nested tables, there is a good tutorial showing how to link nested tables to an external table: follow this demo closely first, in particular, see how the subtable is related to the external table via a dataset parameter.
Of course your case is more complex because you need to do it with dataset scripts and multiple sub-tables. I already did something like this, you need to create one dataset script for each subtable. The key points are:
- In the "parameters" section of each subdisk, create one input parameter and name it, for example, "systemID"
- Create your sub-tables by "drag and drop" each dataset in the external table
- In the "bindings" section of each subcategory, specify the "systemID" parameter in the ID field of the external table
- In the "open" subdiscate event, access the parameter value with this expression: inputParams ["systemID"] This way, you can filter related strings in "myJSONObject".
- It is important that "myJSONObject" is initialized once for all , otherwise the metrics can drop dramatically if they are evaluated at each iteration. For example, evaluate it in "initializing" a report event.
It will not be easy to do this, but these elements should help in achieving this report.
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