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 · Accepted 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!

Shubham Aware · Answer

Doesn't support recursive function calls( you can simulate it by having an expression rule call itself conditionally to compare nested maps, checking property types and combining differences from each level ) For nested structures: Compare each level separately (manual nesting) Flatten structure first, then compare JSON comparison -> a!toJson(obj1) = a!toJson(obj2) (only tells If different, not what) 
 Best approach as per my understanding, Handle each nesting level explicitly with separate comparison logic.

How to find different property of two objects.

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