Loop through JSON object in mysql function

Question

I have a json object which has list of products under a bill. I want to write a mysql function for it which reads the data from the json and iterates over it one by one and

Answer 1

You can use a WHILE loop in conjunction with JSON_LENGTH to achieve this:

DECLARE json, products, product VARCHAR(4000);
DECLARE i INT DEFAULT 0;
SELECT '{"billNo":16,"date":"2017-13-11 09:05:01","customerName":"Vikas","total":350.0,"fixedCharges":100,"taxAmount":25.78,"status":"paid","product":[{"productId":"MRR11","categoryId":72,"categoryName":"Parker Pen","cost":200,"quantity":2,"log":{"supplierId":"725","supplierName":"Rihant General Stores"}},{"productId":"MRR12","categoryId":56,"categoryName":"Drawing Books","cost":150,"quantity":3,"log":{"supplierId":"725","supplierName":"Rihant General Stores"}}]}
' INTO json;

SELECT json->"$.product" INTO products;

WHILE i < JSON_LENGTH(products) DO
    SELECT JSON_EXTRACT(products,CONCAT('$[',i,']')) INTO product;
    SELECT product;
    SELECT i + 1 INTO i;
END WHILE;

You'll probably need to do more than simply 'SELECT product' though ;-)

NOTE: MySQL JSON functions were added in 5.7.8 so you'll need to check your MySQL version first.