{"id":57961,"date":"2023-08-19T16:26:59","date_gmt":"2023-08-19T10:56:59","guid":{"rendered":"https:\/\/www.tothenew.com\/blog\/?p=57961"},"modified":"2024-01-02T17:37:26","modified_gmt":"2024-01-02T12:07:26","slug":"simple-way-to-handle-monetary-data-in-mongodb-in-a-nestjs-application","status":"publish","type":"post","link":"https:\/\/www.tothenew.com\/blog\/simple-way-to-handle-monetary-data-in-mongodb-in-a-nestjs-application\/","title":{"rendered":"Simple way to handle monetary data in MongoDB in a NestJs application"},"content":{"rendered":"
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While building my backend NestJs application, I wanted to store some financial data. The first question I ran into was what schema Type should be for storing data where I want to maintain the data precision.<\/p>\n

Decimal128 came out to be the prescribed official candidate to store the financial data.<\/p>\n

Here\u2019s my initial schema implementation:<\/p>\n

import<\/span> { Prop, Schema, SchemaFactory } from<\/span> '@nestjs\/mongoose'<\/span>;\r\nimport<\/span> mongoose, { Decimal128, HydratedDocument, Types } from<\/span> 'mongoose'<\/span>;\r\n\r\nexport type<\/span> UserDocument = HydratedDocument<User>;\r\n\r\n@Schema({\r\n  toJSON: {\r\n    getters: true,\r\n  },\r\n}<\/span>)<\/span>\r\nexport class<\/span> User<\/span> {\r\n  @Prop()<\/span>\r\n  firstName: string;\r\n\r\n  @Prop()<\/span>\r\n  lastName: string;\r\n\r\n  @Prop({\r\n    default: new Types.Decimal128('0'<\/span>),\r\n    type<\/span>: Types.Decimal128,\r\n  }<\/span>)<\/span>\r\n  total_invested: Decimal128;\r\n\r\n  @Prop({\r\n    default: new Types.Decimal128('0'<\/span>),\r\n    type<\/span>: Types.Decimal128,\r\n  }<\/span>)<\/span>\r\n  target_returns: Decimal128;\r\n\r\n  @Prop({\r\n    default: new Types.Decimal128('0'<\/span>),\r\n    type<\/span>: Types.Decimal128,\r\n  }<\/span>)<\/span>\r\n  target_profit_percent: Decimal128;\r\n\r\n  @Prop({\r\n    default: new Types.Decimal128('0'<\/span>),\r\n    type<\/span>: Types.Decimal128,\r\n  }<\/span>)<\/span>\r\n  actual_returns: Decimal128;\r\n\r\n  @Prop({\r\n    default: new Types.Decimal128('0'<\/span>),\r\n    type<\/span>: Types.Decimal128,\r\n  }<\/span>)<\/span>\r\n  actual_profit_percent: Decimal128;\r\n}\r\n\r\nexport const UserSchema = SchemaFactory.createForClass(User);<\/span><\/pre>\n
There was one small issue that I soon ran into. The database would return the Decimal128 column data in this format:<\/p>\n
{\r\n    \"_id\"<\/span>: \"64d50a0bf9e3e104920dec6a\"<\/span>,\r\n    \"firstName\"<\/span>: \"shiva\"<\/span>,\r\n    \"lastName\"<\/span>: \"chaturvedi\"<\/span>,\r\n    \"total_invested\"<\/span>: {\r\n        \"$numberDecimal<\/span>\"<\/span>: \"0\"<\/span>\r\n    },\r\n    \"target_returns\"<\/span>: {\r\n        \"$numberDecimal<\/span>\"<\/span>: \"0\"<\/span>\r\n    },\r\n    \"target_profit_percent\"<\/span>: {\r\n        \"$numberDecimal<\/span>\"<\/span>: \"0\"<\/span>\r\n    },\r\n    \"actual_returns\"<\/span>: {\r\n        \"$numberDecimal<\/span>\"<\/span>: \"0\"<\/span>\r\n    },\r\n    \"actual_profit_percent\"<\/span>: {\r\n        \"$numberDecimal<\/span>\"<\/span>: \"0\"<\/span>\r\n    },\r\n    \"__v\"<\/span>: 0,\r\n    \"id\"<\/span>: \"64d50a0bf9e3e104920dec6a\"<\/span>\r\n}<\/span><\/pre>\n
Whereas I wanted the database to return transformed results or, simply put, data in a good old-fashioned key-value pair format.<\/p>\n
Solution: Use\u00a0Getters<\/h3>\n
Implementing getters<\/code> your schema props is very easy.<\/p>\n
import<\/span> { Prop, Schema, SchemaFactory } from<\/span> '@nestjs\/mongoose'<\/span>;\r\nimport<\/span> mongoose, { Decimal128, HydratedDocument, Types } from<\/span> 'mongoose'<\/span>;\r\n\r\nexport type<\/span> UserDocument = HydratedDocument<User>;\r\n\r\n@Schema()<\/span>\r\nexport class<\/span> User<\/span> {\r\n  @Prop()<\/span>\r\n  firstName: string;\r\n\r\n  @Prop()<\/span>\r\n  lastName: string;\r\n\r\n  @Prop({\r\n    default: new Types.Decimal128('0'<\/span>),\r\n    type<\/span>: Types.Decimal128,\r\n    get: (v: Types.Decimal128) => v.toString(),\r\n  }<\/span>)<\/span>\r\n  total_invested: Decimal128;\r\n\r\n  @Prop({\r\n    default: new Types.Decimal128('0'<\/span>),\r\n    type<\/span>: Types.Decimal128,\r\n    get: (v: Types.Decimal128) => v.toString(),\r\n  }<\/span>)<\/span>\r\n  target_returns: Decimal128;\r\n\r\n  @Prop({\r\n    default: new Types.Decimal128('0'<\/span>),\r\n    type<\/span>: Types.Decimal128,\r\n    get: (v: Types.Decimal128) => v.toString(),\r\n  }<\/span>)<\/span>\r\n  target_profit_percent: Decimal128;\r\n\r\n  @Prop({\r\n    default: new Types.Decimal128('0'<\/span>),\r\n    type<\/span>: Types.Decimal128,\r\n    get: (v: Types.Decimal128) => v.toString(),\r\n  }<\/span>)<\/span>\r\n  actual_returns: Decimal128;\r\n\r\n  @Prop({\r\n    default: new Types.Decimal128('0'<\/span>),\r\n    type<\/span>: Types.Decimal128,\r\n    get: (v: Types.Decimal128) => v.toString(),\r\n  }<\/span>)<\/span>\r\n  actual_profit_percent: Decimal128;\r\n}\r\n\r\nexport const UserSchema = SchemaFactory.createForClass(User);<\/span><\/pre>\n
Now, let\u2019s test the API again.<\/p>\n
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\u201cWhat am I missing?\u201d I wondered.<\/p>\n
After a short walk on the internet, a good samaritan pointed out that we also need to set getters<\/code> flag as true<\/code> on the @Schema<\/code> decorator as illustrated below:<\/p>\n
import<\/span> { Prop<\/span>, Schema<\/span>, SchemaFactory<\/span> } from<\/span> '@nestjs\/mongoose'<\/span>;\r\nimport<\/span> mongoose, { Decimal128<\/span>, HydratedDocument<\/span>, Types<\/span> } from<\/span> 'mongoose'<\/span>;\r\n\r\nexport<\/span> type<\/span> UserDocument<\/span> = HydratedDocument<\/span><User<\/span>>;\r\n\r\n@Schema<\/span>({\r\n  toJSON<\/span>: {\r\n    getters<\/span>: true<\/span>,\r\n  },\r\n})<\/span><\/pre>\n
This enables the props to execute\/use their getter functions.<\/p>\n
Let\u2019s test again!<\/p>\n
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Hallelujah ? ?<\/p>\n
Want to know more about Decimal128 Type? Read this<\/a> beautiful article written by Ken W. Alger<\/a> on MongoDB official website.<\/p><\/blockquote>\n<\/div>\n<\/div>\n<\/section>\n
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P.S.: If you feel something can be improved or lacks proper explanation, drop us a note in the comment section below, and we’ll try to<\/p>\n<\/div>\n<\/div>\n<\/section>\n
<\/div>","protected":false},"excerpt":{"rendered":"
While building my backend NestJs application, I wanted to store some financial data. The first question I ran into was what schema Type should be for storing data where I want to maintain the data precision. Decimal128 came out to be the prescribed official candidate to store the financial data. Here\u2019s my initial schema implementation: […]<\/p>\n","protected":false},"author":1535,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"iawp_total_views":53},"categories":[4684,1185,1],"tags":[4846,5327],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/posts\/57961"}],"collection":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/users\/1535"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/comments?post=57961"}],"version-history":[{"count":4,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/posts\/57961\/revisions"}],"predecessor-version":[{"id":59679,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/posts\/57961\/revisions\/59679"}],"wp:attachment":[{"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/media?parent=57961"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/categories?post=57961"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tothenew.com\/blog\/wp-json\/wp\/v2\/tags?post=57961"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}