76 lines
3.7 KiB
Markdown
76 lines
3.7 KiB
Markdown
# pg-types
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This is the code that turns all the raw text from postgres into JavaScript types for [node-postgres](https://github.com/brianc/node-postgres.git)
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## use
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This module is consumed and exported from the root `pg` object of node-postgres. To access it, do the following:
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```js
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var types = require('pg').types
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```
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Generally what you'll want to do is override how a specific data-type is parsed and turned into a JavaScript type. By default the PostgreSQL backend server returns everything as strings. Every data type corresponds to a unique `OID` within the server, and these `OIDs` are sent back with the query response. So, you need to match a particluar `OID` to a function you'd like to use to take the raw text input and produce a valid JavaScript object as a result. `null` values are never parsed.
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Let's do something I commonly like to do on projects: return 64-bit integers `(int8)` as JavaScript integers. Because JavaScript doesn't have support for 64-bit integers node-postgres cannot confidently parse `int8` data type results as numbers because if you have a _huge_ number it will overflow and the result you'd get back from node-postgres would not be the result in the datbase. That would be a __very bad thing__ so node-postgres just returns `int8` results as strings and leaves the parsing up to you. Let's say that you know you don't and wont ever have numbers greater than `int4` in your database, but you're tired of recieving results from the `COUNT(*)` function as strings (because that function returns `int8`). You would do this:
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```js
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var types = require('pg').types
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types.setTypeParser(20, function(val) {
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return parseInt(val)
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})
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```
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__boom__: now you get numbers instead of strings.
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Just as another example -- not saying this is a good idea -- let's say you want to return all dates from your database as [moment](http://momentjs.com/docs/) objects. Okay, do this:
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```js
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var types = require('pg').types
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var moment = require('moment')
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var parseFn = function(val) {
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return val === null ? null : moment(val)
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}
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types.setTypeParser(types.builtins.TIMESTAMPTZ, parseFn)
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types.setTypeParser(types.builtins.TIMESTAMP, parseFn)
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```
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_note: I've never done that with my dates, and I'm not 100% sure moment can parse all the date strings returned from postgres. It's just an example!_
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If you're thinking "gee, this seems pretty handy, but how can I get a list of all the OIDs in the database and what they correspond to?!?!?!" worry not:
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```bash
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$ psql -c "select typname, oid, typarray from pg_type order by oid"
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```
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If you want to find out the OID of a specific type:
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```bash
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$ psql -c "select typname, oid, typarray from pg_type where typname = 'daterange' order by oid"
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```
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:smile:
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## license
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The MIT License (MIT)
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Copyright (c) 2014 Brian M. Carlson
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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