pgtalk

More type safe SQL query building and execution using Go code generated (pgtalk-gen) from PostgreSQL table definitions. After code generation, you get a Go type for each table or view with functions to create a QuerySet or MutationSet value. Except for query exectution, all operations on a QuerySet or MutationSet will return a copy of that value. This package requires Go SDK version 1.18+ because it uses type parameterization.

status

This package is used in production, e.g. https://ag5.com, and its programming API is stable since v1.0.0.

install

go install github.com/emicklei/pgtalk/cmd/pgtalk-gen@latest

how to run the generator

The user in the connection string must have the right privileges to read schema information.

PGTALK_CONN=postgresql://usr:pwd@localhost:5432/database pgtalk-gen -s public -o yourpackage
go fmt ./...

If you want to include and/or exclude table names, use additional flags such as:

-include "address.*,employee.*" -exclude "org.*"

or views

-views -o yourpackage -include "skills.*"

examples

These examples are from the test package in which a few database tables files (categories,products,things) are generated.

Insert

m := products.Insert(
	products.ID.Set(10),
	products.Code.Set("testit"),
	products.CategoryID.Set(1))

it := m.Exec(aConnection)
if err := it.Err(); err != nil {
	....
}

or by example:

p := new(products.Product)
p.SetID(10).SetCode("testit").SetCategoryID(1)		
m := products.Insert(p.Setters()...)

Update

m := products.Update(
		products.Code.Set("testme"),
		products.CategoryID.Set(1)).
	Where(products.ID.Equals(10)).
	Returning(products.Code)

it := m.Exec(aConnection)	
for it.HasNext() {
	p, err := products.Next(p) // p is a *product.Product
	t.Logf("%s,%s", *p.Code)
}		

or by example

p := new(products.Product)
p.SetID(10).SetCode("testme").SetCategoryID(1)		
m := products.Update(p.Setters()...).
		Where(products.ID.Equals(p.ID)).
		Returning(products.Code)

or by collecting columns first

cols := NewColumns()
cols.Add(products.Code.Set("testme"))
if categoryWhasChanged {
	cols.Add(products.CategoryID.Set(changedValue))
}
m := products.Update(cols...).Where(products.ID.Equals(10)).

Delete

m := products.Delete().Where(products.ID.Equals(10))

_ = m.Exec(aConnection)

Select

q := products.Select(products.Code).Where(products.Code.Equals("F42"))

products, err := q.Exec(aConnection) // products is a []*product.Product

Arbitrary SQL expressions

q := products.Select(products.ID, pgtalk. SQLAs("UPPER(p1.Code)", "upper"))

// SELECT p1.id,UPPER(p1.Code) AS upper FROM public.products p1

list, _ := q.Exec(context.Background(),aConnection)
for _, each := range list {
	upper := each.GetExpressionResult("upper").(string)
	...
}

SQL query records as maps

q := products.Select(products.ID, pgtalk. SQLAs("UPPER(p1.Code)", "upper"))

// SELECT p1.id,UPPER(p1.Code) AS upper FROM public.products p1

listOfMaps, _ := q.ExecIntoMaps(context.Background(),aConnection)
for _, each := range listOfMaps {
	id := products.ID.Get(each).(pgtype.UUID)
	upper := each["upper"].(string)
	...
}

Using Query parameter

p := NewParameter("F42")
q := products.Select(products.Code).Where(products.Code.Equals(p))

// SELECT p1.code FROM public.products p1 WHERE (p1.code = $1)
// with $1 = "F42"

Joins

Left Outer Join

q :=products.Select(products.Code).Where(products.Code.Equals("F42")).
    LeftOuterJoin(categories.Select(categories.Title)).
    On(products.ID.Equals(categories.ID))

it, _ := q.Exec(aConnection)
for it.HasNext() {
	p := new(products.Product)
	c := new(categories.Category)
	_ = it.Next(p, c)
	t.Logf("%s,%s", *p.Code, *c.Title)
}

Multi Join

pSet := products.Select(products.ID, products.Code, products.Title)
fSet := features.Select(features.ID, features.Code, features.Title)
rSet := product_feature.Select(product_feature.ProductId, product_feature.FeatureId)

query := pSet.LeftOuterJoin(rSet).On(product_feature.ProductId.Equals(products.ID)).
	LeftOuterJoin(fSet).On(product_feature.FeatureId.Equals(features.ID)).
	Named("products-and-features")

it, err := query.Exec(ctx, conn)
...

for it.HasNext() {
	var product products.Product
	var feature features.Feature
	var relation product_feature.ProductFeature
	err := it.Next(&product, &relation, &feature)
	...
}

Text Search

Setting a string value for a tsvector typed column called "title_tokens".

mut := categories.Insert(
	categories.ID.Set(1234),
	categories.Title.Set(convert.StringToText(txt)),
	pgtalk.NewTSVector(categories.TitleTokens, txt),
)

Using tsquery in a search condition

q := categories.
	Select(categories.Columns()...).
	Where(pgtalk.NewTSQuery(categories.TitleTokens, "quick"))

Union, Intersect, Except

QuerySets can be combined into one using any of UNION, INTERSECT or EXCEPT with nesting. Because you typically collect fields from different tables, which are mapped to different Go structs, you can only execute the query with Go maps are results.

In the example below, each set is extended with a custom SQL expression to have a type indicator.

left := categories.Select(categories.ID, pgtalk.SQLAs("'category'", "type"))
right := products.Select(products.ID, pgtalk.SQLAs("'product'", "type"))
q := left.Union(right)
list, err := q.ExecIntoMaps(context.Background(), testConnect)

supported Column Types

• bigint
• integer
• jsonb
• json
• uuid
• point
• interval
• timestamp with time zone
• date
• text
• character varying
• numeric
• boolean
• timestamp without time zone
• daterange
• bytea
• text[]
• citext
• double precision
• decimal
• money
• xml
• real
• smallint
• time without time zone
• character
• line
• lseg
• box
• path
• polygon
• circle
• cidr
• inet
• macaddr
• bit
• bit varying

Send me a PR for a missing type available from https://www.postgresql.org/docs/9.5/datatype.html by modifying mapping.go in the cmd/pgtalk-gen package.

custom datatype mappping

If your datatype can be aliased (use) to one of the supported types then you can define such mapping in a configuration file.

pgtalk-gen -mapping your-mapping.json

An example of such as mapping file your-mapping.json:

{
	"character(26)": {
		"use": "character varying"
	}
}

If your datatype cannot be aliased then you can write the missing logic for a datatype and an accessor type. See example test/types/real.go for such an implementation. The configuration for this mapping is:

{
	"real":{
		"nullableFieldType":"types.Real",
		"newAccessFuncName":"types.NewRealAccess",
		"imports": ["github.com/emicklei/pgtalk/test/types"]
	}
}

cache table definitions read from database

If you do not want to add generated sources to your SCM (source code management system e.g. git) then build systems and other developers need to re-generated them. The pgtalk-gen uses table definitions from an active database server to generate Go table types. With the -cache option, this tool can store those definitions in a JSON file which then can be used instead and you add that file to your SCM. It is the responsibility of the developer to update it (by deleting it) upon each table definition change in the database. See the test folder for an example; just run all the tasks in the Makefile.

(c) 2025, https://ernestmicklei.com. MIT License.