How to find different property of two objects.

Question

I have two objects they all the same type. I want to compare the two objects and extract which properties are different. Besides using a loop to iterate, is there a better way?

Shubham Aware · Answer

Without Loop is not possible. No built-in way to dynamically index multiple properties without iteration. a!localVariables(
 local!employee1: {
 name: "John",
 age: 30,
 dept: "IT",
 salary: 50000
 },
 local!employee2: {
 name: "John",
 age: 35,
 dept: "IT", 
 salary: 55000
 },

 /* Get all property names */
 local!allKeys: a!keys(local!employee1),

 /* Check which properties are different */
 local!areEqual: a!forEach(
 local!allKeys,
 index(local!employee1, fv!item) = index(local!employee2, fv!item)
 ),

 /* Find properties with different values */
 local!differentProps: index(
 local!allKeys,
 wherecontains(false, local!areEqual),
 null
 ),

 /* Show results */
 {
 differentProperties: local!differentProps,

 oldValues: a!forEach(
 local!differentProps,
 index(local!employee1, fv!item, null)
 ),
 /* Output: {30, 50000} */

 newValues: a!forEach(
 local!differentProps,
 index(local!employee2, fv!item, null)
 )
 /* Output: {35, 55000} */
 }
)

Harsha Sharma · Answer

If you want just to check whether the variables/datasets are different or not then convert the datasets into json using a!toJson() and then compare like 
 a!tojson(a!map(key: 2, value: 2)) = a!tojson(a!map(key: 1, value: 2)) 
 If you want a list of attributes and values which vary between two datasets then a!foreach() is needed atleast once to parse and check each field in the datatype. 
 Below is a solution with two expressions which can help with this part. In one expression we just have simple expression to compare 2 values which returns true if values dont match. 
 
 In main expression we have code like below which filters and returns the field and values where match failed. 
 a!localVariables(
 local!map1: { name: "Alex", age: "22", dob: today() },
 local!map2: { name: "Alexa", age: "22", dob: today() - 4 },
 local!keys: a!keys(local!map1),
 a!foreach(
 local!keys,
 a!map(
 field: fv!item,
 value: filter(
 rule!HSS_CompareValues,
 merge(
 { index(local!map1, fv!item, {}) },
 { index(local!map2, fv!item, {}) },
 
 )
 )
 )
 )
) 
 As this uses just one foreach() which iterates for each field in a datatype it will be run for fixed times always and wont affect the performance adversely. Hope this helps!