Delete data from object

Question

I have below object and need to delete the column from the result, I will get the column name dynamically. Could you please help me how to delete the column and its corresponding object based on column name {"columnname":"couln2", "datatype":null} Array is:

{
"tabl1":
{"tablename":"tabl1","tablecolumns":"yes","patternCheckStatus":true,
"columns": [{"columnname":"column1","datatype":"Numeric","patternregex":"jjj"},{"columnname":"column2","datatype":"UpperCase","patternregex":"hkl;;"}]},
"table2":{"tablename":"table2","tablecolumns":"yes","patternCheckStatus":null,
"columns":[{"columnname":"t2column","datatype":"Alphabetic"}]
}}

let arr = 
 {"tabl1":{"tablename":"tabl1","tablecolumns":"yes","patternCheckStatus":true,"columns":[{"columnname":"column1","datatype":"Numeric","patternregex":"jjj"},{"columnname":"column2","datatype":"UpperCase","patternregex":"hkl;;"}]},"table2":{"tablename":"table2","tablecolumns":"yes","patternCheckStatus":null,"columns":[{"columnname":"t2column","datatype":"Alphabetic"}]}}
 
 const result = arr.reduce((a, {tablename, tablecolumns, columnname, datatype}) => {
 a[tablename] = a[tablename] || {tablename, tablecolumns, columns: []};
 if (columnname)
 a[tablename].columns.push({columnname, datatype});
 return a;
 },{})
 console.log(Object.values(result));

• Ahsan: Share the resulting array as well that you need
• nonopolarity: you mean delete the property column and delete tabl2_colu? Where is tabl2_colu?
• user2319726: @Ahsan ,@nopole, please see the updated array details

Answer 1

I cannot understand your question correctly but I think you want to delete a specific object having a specific columnname value from the arr. You can filter the arr like this:

function deleteColumn (column) {
 let newArr = arr.filter(item => {
 return item.columnname !== column
 })
 return newArr
}

Then you can run:

deleteColumn('tabl2_colu') // Will return an array without object having any columnname = 'tabl2_colu'

• user2319726: thanks for the answer.. please see the updated array

Answer 2

If you want to get rid of some columns in array, then you can use Object.entries while map your array into another array:

let propertyName = 'tablename';
arr.map(s=> Object.fromEntries(Object.entries(s).filter(([k, v]) => k!= propertyName)))

An example:

let arr = [
 {"tablename":"table1","tablecolumns":"yes"},
 {"tablename":"table1","columnname":"col1","datatype":"Alphabetic"},
 {"tablename":"table2","tablecolumns":"yes"},
 {"tablename":"table2","columnname":"tabl2_colu","datatype":null},
 {"tablename":"table2","columnname":"tab2_col2","datatype":"Numeric"}
];
const result = arr.reduce((a, {tablename, tablecolumns, columnname, datatype}) => {
 a[tablename] = a[tablename] || {tablename, tablecolumns, columns: []};
 if (columnname)
 a[tablename].columns.push({columnname, datatype});
 return a;
 },{})
let propertyName = 'tablename';
console.log(Object.values(result)
 .map(s=> Object.fromEntries(Object.entries(s)
 .filter(([k, v]) => k!= propertyName))));

UPDATE:

You can filter your array based in columnname:

let columnname = 'column2';
obj.tabl1.columns = obj.tabl1.columns.filter(f=> f.columnname != columnname);

An example:

let obj = { "tabl1":
 { "tablename": "tabl1", "tablecolumns": "yes", "patternCheckStatus": true,
 "columns": [{ "columnname": "column1", "datatype": "Numeric", "patternregex": "jjj" },
 { "columnname": "column2", "datatype": "UpperCase", "patternregex": "hkl;;" }] }, };
let columnname = 'column2';
obj.tabl1.columns = obj.tabl1.columns.filter(f=> f.columnname != columnname);
console.log(obj);

• user2319726: thansk for the answer but i am getting below error , Property 'Fromentries' does not exist on type 'ObjectConstructor'.ts
• StepUp: @user2319726 it looks like you need to add "lib": ["es2017"] into your settings. Here yo can read more :)
• user2319726: I need to remove complete columnname object , i think now its deleting only column name key value, { "tabl1": {"tablename":"tabl1","tablecolumns":"yes","patternCheckStatus":true, "columns": [{"columnname":"column1","datatype":"Numeric","patternregex":"jjj"}, }}
• StepUp: @user could you write the desired output?
• user2319726: Please see the below , before delete: { "tabl1": {"tablename":"tabl1","tablecolumns":"yes","patternCheckStatus":true, "columns": [{"columnname":"column1","datatype":"Numeric","patternregex":"jjj"},{"columnname":"column2","datatype":"UpperCase","patternregex":"hkl;;"}]}, } expected after deleting { "tabl1": {"tablename":"tabl1","tablecolumns":"yes","patternCheckStatus":true, "columns": [{"columnname":"column1","datatype":"Numeric","patternregex":"jjj"}]}, }

Answer 3

One way would be to loop through the array of objects, find the one you want to delete by the mean of its property identifier and them just remove that object from the array:

arr = [
{"tablename":"table1","tablecolumns":"yes"},
{"tablename":"table1","columnname":"col1","datatype":"Alphabetic"},
{"tablename":"table2","tablecolumns":"yes"},
{"tablename":"table2","columnname":"tabl2_colu","datatype":null},
{"tablename":"table2","columnname":"tab2_col2","datatype":"Numeric"}
];
function remove_object_by_colname( colname )
 arr.forEach(function( arrayItem, index ) {
 if ( arrayItem.columnname == colname ) {
 arr.splice( index, 1 );
 }
 };
} );
remove_object_by_colname( 'tabl2_colu' ); // Will remove the 4th object from arr.