color = Color.FromArgb(jsonParam['color']['a'],jsonParam['color']['r'],jsonParam['color']['g'],jsonParam['color']['b'])

rule = None
for ruleTested in coloring:
    ruleType = clr.GetClrType(type(ruleTested)).ToString()
    if((ruleType == 'Spotfire.Dxp.Application.Visuals.ConditionalColoring.ExpressionColorRule') and (ruleTested.ManualDisplayName == jsonParam['displayName'])):
        rule = ruleTested
        break;
if(rule == None):
    rule = coloring.AddExpressionRule(jsonParam['expression'], color)

if(jsonParam['displayName'] != None):
    rule.ManualDisplayName = jsonParam['displayName']
rule.Color = color
rule.Expression = jsonParam['expression']