Working /transactions endpoint with DB connection

Adds the database abstraction layer (DAL) with a Transactions method
and a Connection object to encapsulate the DB open connection.
Includes a DAL unit test using the go-sqlmock library.

Connection to a PostgreSQL database using environment variables to
store the secrets.

Overall, with the /transactions endpoint requesting directly to the DB,
this patch finish the tracer bullet project.

Issues #1, #5, #6 and #7

cmd/api-server/main.go

@@ -0,0 +1,130 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+
+	"git.rosemyrtle.work/personal-finance/server/internal/dal"
+	"git.rosemyrtle.work/personal-finance/server/internal/entities"
+
+	"github.com/gin-gonic/gin"
+	"github.com/joho/godotenv"
+	"github.com/shopspring/decimal"
+)
+
+// Transaction struct represents a transaction
+type Transaction struct {
+	Id          int64   `json:"id"`
+	Date        string  `json:"date"`
+	Description string  `json:"description"`
+	Value       float64 `json:"value"`
+	Category    string  `json:"category,omitempty"`
+}
+
+// Bank struct represents a bank
+type Bank struct {
+	ID         string `json:"id"`
+	Name       string `json:"name"`
+	NordigenID string `json:"nordigenId,omitempty"`
+}
+
+type Env struct {
+	db *dal.Connection
+}
+
+func (e *Env) retrieveTransactions(c *gin.Context) {
+	// Handle the logic for retrieving transactions here
+	// limit := c.Query("limit")
+	// offset := c.Query("offset")
+	// bank := c.Query("bank")
+	// sort := c.Query("sort")
+
+	transactions := e.db.Transactions()
+	var ret []Transaction
+
+	for _, t := range transactions {
+		year, month, day := t.Date.Date()
+		var b strings.Builder
+		fmt.Fprintf(&b, "%d-%d-%d", year, month, day)
+		ret = append(ret, Transaction{t.Id, b.String(), t.Description, t.Value.InexactFloat64(), t.Category})
+	}
+
+	c.JSON(http.StatusOK, ret)
+}
+
+func (e *Env) retrieveTransactionByID(c *gin.Context) {
+	// Handle the logic for retrieving a transaction by ID here
+	// transactionID := c.Param("transactionId")
+
+	// Placeholder response
+	transaction := entities.Transaction{
+		Id:          1,
+		Date:        time.Date(2024, 01, 24, 0, 0, 0, 0, time.UTC),
+		Description: "Groceries",
+		Value:       decimal.NewFromFloat(-50.0),
+		Category:    "Food",
+	}
+
+	c.JSON(http.StatusOK, transaction)
+}
+
+func (e *Env) retrieveBanks(c *gin.Context) {
+	// Handle the logic for retrieving banks here
+
+	// Placeholder response
+	banks := []Bank{
+		{ID: "1", Name: "Bank A", NordigenID: "uuid1"},
+		{ID: "2", Name: "Bank B", NordigenID: "uuid2"},
+	}
+
+	c.JSON(http.StatusOK, banks)
+}
+
+func (e *Env) retrieveBankByID(c *gin.Context) {
+	// Handle the logic for retrieving a bank by ID here
+	bankID := c.Param("bankId")
+
+	// Placeholder response
+	bank := Bank{ID: bankID, Name: "Bank A", NordigenID: "uuid1"}
+
+	c.JSON(http.StatusOK, bank)
+}
+
+func main() {
+	if err := godotenv.Load(); err != nil {
+		log.Fatal("Error loading .env file")
+		return
+	}
+
+	user := os.Getenv("PG_USER")
+	pass := os.Getenv("PG_PASSWORD")
+	location := os.Getenv("PG_URL")
+	database := os.Getenv("PG_DB")
+
+	credentials := entities.Credentials{Database: "postgres://" + user + ":" + pass + "@" + location + "/" + database}
+	db, err := dal.Open(&credentials)
+	if err != nil {
+		log.Fatal(err)
+		return
+	}
+	defer db.Close()
+
+	router := gin.Default()
+
+	env := Env{db: db}
+
+	// Routes
+	router.GET("/transactions", env.retrieveTransactions)
+	router.GET("/transactions/:transactionId", env.retrieveTransactionByID)
+	router.GET("/banks", env.retrieveBanks)
+	router.GET("/banks/:bankId", env.retrieveBankByID)
+
+	// Start server
+	port := 8080
+	fmt.Printf("Server is running on :%d...\n", port)
+	router.Run(fmt.Sprintf(":%d", port))
+}

docs/openapi.yaml

@@ -0,0 +1,160 @@
+openapi: 3.0.3
+info:
+  title: Personal Finance - OpenAPI 3.0
+  description: |
+    Personal Finance Server
+  contact:
+    email: finance@murta.dev
+  license:
+    name: GNU General Public License v3.0 or later
+    url: https://www.gnu.org/licenses/gpl-3.0-standalone.html
+  version: 0.0.1
+
+paths:
+  /transactions:
+    get:
+      summary: Retrieve existing transactions
+      operationId: retrieveTransactions
+      parameters:
+        - name: limit
+          in: query
+          description: number of transactions to return
+          schema:
+            type: integer
+            format: int32
+            default: 100
+            minimum: 0
+        - name: offset
+          in: query
+          description: offset from where to retrieve transactions
+          schema:
+            type: integer
+            format: int32
+            default: -1
+        - name: bank
+          in: query
+          description: ID of the bank
+          schema:
+            type: string
+        - name: sort
+          in: query
+          description: field name by which to sort
+          schema:
+            type: string
+      responses:
+        "200":
+          description: Successful operation
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Transactions"
+        "404":
+          description: No transactions
+
+  /transactions/{transactionId}:
+    get:
+      summary: Find transaction by ID
+      operationId: retrieveTransactions
+      parameters:
+        - name: transactionId
+          in: path
+          description: ID of transaction to return
+          required: true
+          schema:
+            type: integer
+            format: int64
+      responses:
+        "200":
+          description: Successful operation
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Transaction"
+        "400":
+          description: Invalid ID supplied
+        "404":
+          description: Transaction not found
+
+  /banks:
+    get:
+      summary: Retrieve existing banks
+      operationId: retrieveBanks
+      responses:
+        "200":
+          description: Successful operation
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Banks"
+        "404":
+          description: No banks
+
+  /banks/{bankId}:
+    get:
+      summary: Find bank by ID
+      operationId: retrieveBank
+      parameters:
+        - name: bankId
+          in: path
+          description: ID of bank to return
+          required: true
+          schema:
+            type: integer
+            format: int64
+      responses:
+        "200":
+          description: Successful operation
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Bank"
+        "400":
+          description: Invalid ID supplied
+        "404":
+          description: Bank not found
+
+components:
+  schemas:
+    Transaction:
+      type: object
+      properties:
+        id:
+          type: integer
+          format: int64
+          minimum: 0
+        date:
+          type: string
+          format: date
+        description:
+          type: string
+        value:
+          type: number
+          format: float
+        category:
+          type: string
+      required:
+        - id
+        - date
+        - description
+        - value
+    Transactions:
+      type: array
+      items:
+        $ref: "#/components/schemas/Transaction"
+    Bank:
+      type: object
+      properties:
+        id:
+          type: string
+        name:
+          type: string
+        nordigenId:
+          type: string
+          format: uuid
+      required:
+        - id
+        - name
+    Banks:
+      type: array
+      items:
+        $ref: "#/components/schemas/Bank"

go.mod

@@ -1,3 +1,40 @@
 module git.rosemyrtle.work/personal-finance/server
 
 go 1.21.1
+
+require github.com/gin-gonic/gin v1.9.1
+
+require (
+	github.com/DATA-DOG/go-sqlmock v1.5.2 // indirect
+	github.com/bytedance/sonic v1.9.1 // indirect
+	github.com/chenzhuoyu/base64x v0.0.0-20221115062448-fe3a3abad311 // indirect
+	github.com/gabriel-vasile/mimetype v1.4.2 // indirect
+	github.com/gin-contrib/sse v0.1.0 // indirect
+	github.com/go-playground/locales v0.14.1 // indirect
+	github.com/go-playground/universal-translator v0.18.1 // indirect
+	github.com/go-playground/validator/v10 v10.14.0 // indirect
+	github.com/goccy/go-json v0.10.2 // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a // indirect
+	github.com/jackc/pgx/v5 v5.5.3 // indirect
+	github.com/jackc/puddle/v2 v2.2.1 // indirect
+	github.com/joho/godotenv v1.5.1 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/klauspost/cpuid/v2 v2.2.4 // indirect
+	github.com/leodido/go-urn v1.2.4 // indirect
+	github.com/mattn/go-isatty v0.0.19 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/pelletier/go-toml/v2 v2.0.8 // indirect
+	github.com/shopspring/decimal v1.3.1 // indirect
+	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
+	github.com/ugorji/go/codec v1.2.11 // indirect
+	golang.org/x/arch v0.3.0 // indirect
+	golang.org/x/crypto v0.17.0 // indirect
+	golang.org/x/net v0.10.0 // indirect
+	golang.org/x/sync v0.1.0 // indirect
+	golang.org/x/sys v0.15.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
+	google.golang.org/protobuf v1.30.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -0,0 +1,101 @@
+github.com/DATA-DOG/go-sqlmock v1.5.2 h1:OcvFkGmslmlZibjAjaHm3L//6LiuBgolP7OputlJIzU=
+github.com/DATA-DOG/go-sqlmock v1.5.2/go.mod h1:88MAG/4G7SMwSE3CeA0ZKzrT5CiOU3OJ+JlNzwDqpNU=
+github.com/bytedance/sonic v1.5.0/go.mod h1:ED5hyg4y6t3/9Ku1R6dU/4KyJ48DZ4jPhfY1O2AihPM=
+github.com/bytedance/sonic v1.9.1 h1:6iJ6NqdoxCDr6mbY8h18oSO+cShGSMRGCEo7F2h0x8s=
+github.com/bytedance/sonic v1.9.1/go.mod h1:i736AoUSYt75HyZLoJW9ERYxcy6eaN6h4BZXU064P/U=
+github.com/chenzhuoyu/base64x v0.0.0-20211019084208-fb5309c8db06/go.mod h1:DH46F32mSOjUmXrMHnKwZdA8wcEefY7UVqBKYGjpdQY=
+github.com/chenzhuoyu/base64x v0.0.0-20221115062448-fe3a3abad311 h1:qSGYFH7+jGhDF8vLC+iwCD4WpbV1EBDSzWkJODFLams=
+github.com/chenzhuoyu/base64x v0.0.0-20221115062448-fe3a3abad311/go.mod h1:b583jCggY9gE99b6G5LEC39OIiVsWj+R97kbl5odCEk=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/gabriel-vasile/mimetype v1.4.2 h1:w5qFW6JKBz9Y393Y4q372O9A7cUSequkh1Q7OhCmWKU=
+github.com/gabriel-vasile/mimetype v1.4.2/go.mod h1:zApsH/mKG4w07erKIaJPFiX0Tsq9BFQgN3qGY5GnNgA=
+github.com/gin-contrib/sse v0.1.0 h1:Y/yl/+YNO8GZSjAhjMsSuLt29uWRFHdHYUb5lYOV9qE=
+github.com/gin-contrib/sse v0.1.0/go.mod h1:RHrZQHXnP2xjPF+u1gW/2HnVO7nvIa9PG3Gm+fLHvGI=
+github.com/gin-gonic/gin v1.9.1 h1:4idEAncQnU5cB7BeOkPtxjfCSye0AAm1R0RVIqJ+Jmg=
+github.com/gin-gonic/gin v1.9.1/go.mod h1:hPrL7YrpYKXt5YId3A/Tnip5kqbEAP+KLuI3SUcPTeU=
+github.com/go-playground/locales v0.14.1 h1:EWaQ/wswjilfKLTECiXz7Rh+3BjFhfDFKv/oXslEjJA=
+github.com/go-playground/locales v0.14.1/go.mod h1:hxrqLVvrK65+Rwrd5Fc6F2O76J/NuW9t0sjnWqG1slY=
+github.com/go-playground/universal-translator v0.18.1 h1:Bcnm0ZwsGyWbCzImXv+pAJnYK9S473LQFuzCbDbfSFY=
+github.com/go-playground/universal-translator v0.18.1/go.mod h1:xekY+UJKNuX9WP91TpwSH2VMlDf28Uj24BCp08ZFTUY=
+github.com/go-playground/validator/v10 v10.14.0 h1:vgvQWe3XCz3gIeFDm/HnTIbj6UGmg/+t63MyGU2n5js=
+github.com/go-playground/validator/v10 v10.14.0/go.mod h1:9iXMNT7sEkjXb0I+enO7QXmzG6QCsPWY4zveKFVRSyU=
+github.com/goccy/go-json v0.10.2 h1:CrxCmQqYDkv1z7lO7Wbh2HN93uovUHgrECaO5ZrCXAU=
+github.com/goccy/go-json v0.10.2/go.mod h1:6MelG93GURQebXPDq3khkgXZkazVtN9CRI+MGFi0w8I=
+github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
+github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
+github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
+github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a h1:bbPeKD0xmW/Y25WS6cokEszi5g+S0QxI/d45PkRi7Nk=
+github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a/go.mod h1:5TJZWKEWniPve33vlWYSoGYefn3gLQRzjfDlhSJ9ZKM=
+github.com/jackc/pgx/v5 v5.5.3 h1:Ces6/M3wbDXYpM8JyyPD57ivTtJACFZJd885pdIaV2s=
+github.com/jackc/pgx/v5 v5.5.3/go.mod h1:ez9gk+OAat140fv9ErkZDYFWmXLfV+++K0uAOiwgm1A=
+github.com/jackc/puddle/v2 v2.2.1 h1:RhxXJtFG022u4ibrCSMSiu5aOq1i77R3OHKNJj77OAk=
+github.com/jackc/puddle/v2 v2.2.1/go.mod h1:vriiEXHvEE654aYKXXjOvZM39qJ0q+azkZFrfEOc3H4=
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
+github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=
+github.com/json-iterator/go v1.1.12/go.mod h1:e30LSqwooZae/UwlEbR2852Gd8hjQvJoHmT4TnhNGBo=
+github.com/kisielk/sqlstruct v0.0.0-20201105191214-5f3e10d3ab46/go.mod h1:yyMNCyc/Ib3bDTKd379tNMpB/7/H5TjM2Y9QJ5THLbE=
+github.com/klauspost/cpuid/v2 v2.0.9/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
+github.com/klauspost/cpuid/v2 v2.2.4 h1:acbojRNwl3o09bUq+yDCtZFc1aiwaAAxtcn8YkZXnvk=
+github.com/klauspost/cpuid/v2 v2.2.4/go.mod h1:RVVoqg1df56z8g3pUjL/3lE5UfnlrJX8tyFgg4nqhuY=
+github.com/leodido/go-urn v1.2.4 h1:XlAE/cm/ms7TE/VMVoduSpNBoyc2dOxHs5MZSwAN63Q=
+github.com/leodido/go-urn v1.2.4/go.mod h1:7ZrI8mTSeBSHl/UaRyKQW1qZeMgak41ANeCNaVckg+4=
+github.com/mattn/go-isatty v0.0.19 h1:JITubQf0MOLdlGRuRq+jtsDlekdYPia9ZFsB8h/APPA=
+github.com/mattn/go-isatty v0.0.19/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
+github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd h1:TRLaZ9cD/w8PVh93nsPXa1VrQ6jlwL5oN8l14QlcNfg=
+github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
+github.com/modern-go/reflect2 v1.0.2 h1:xBagoLtFs94CBntxluKeaWgTMpvLxC4ur3nMaC9Gz0M=
+github.com/modern-go/reflect2 v1.0.2/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjYzDa0/r8luk=
+github.com/pelletier/go-toml/v2 v2.0.8 h1:0ctb6s9mE31h0/lhu+J6OPmVeDxJn+kYnJc2jZR9tGQ=
+github.com/pelletier/go-toml/v2 v2.0.8/go.mod h1:vuYfssBdrU2XDZ9bYydBu6t+6a6PYNcZljzZR9VXg+4=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/shopspring/decimal v1.3.1 h1:2Usl1nmF/WZucqkFZhnfFYxxxu8LG21F6nPQBE5gKV8=
+github.com/shopspring/decimal v1.3.1/go.mod h1:DKyhrW/HYNuLGql+MJL6WCR6knT2jwCFRcu2hWCYk4o=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+github.com/stretchr/testify v1.8.3/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+github.com/twitchyliquid64/golang-asm v0.15.1 h1:SU5vSMR7hnwNxj24w34ZyCi/FmDZTkS4MhqMhdFk5YI=
+github.com/twitchyliquid64/golang-asm v0.15.1/go.mod h1:a1lVb/DtPvCB8fslRZhAngC2+aY1QWCk3Cedj/Gdt08=
+github.com/ugorji/go/codec v1.2.11 h1:BMaWp1Bb6fHwEtbplGBGJ498wD+LKlNSl25MjdZY4dU=
+github.com/ugorji/go/codec v1.2.11/go.mod h1:UNopzCgEMSXjBc6AOMqYvWC1ktqTAfzJZUZgYf6w6lg=
+golang.org/x/arch v0.0.0-20210923205945-b76863e36670/go.mod h1:5om86z9Hs0C8fWVUuoMHwpExlXzs5Tkyp9hOrfG7pp8=
+golang.org/x/arch v0.3.0 h1:02VY4/ZcO/gBOH6PUaoiptASxtXU10jazRCP865E97k=
+golang.org/x/arch v0.3.0/go.mod h1:5om86z9Hs0C8fWVUuoMHwpExlXzs5Tkyp9hOrfG7pp8=
+golang.org/x/crypto v0.9.0 h1:LF6fAI+IutBocDJ2OT0Q1g8plpYljMZ4+lty+dsqw3g=
+golang.org/x/crypto v0.9.0/go.mod h1:yrmDGqONDYtNj3tH8X9dzUun2m2lzPa9ngI6/RUPGR0=
+golang.org/x/crypto v0.17.0 h1:r8bRNjWL3GshPW3gkd+RpvzWrZAwPS49OmTGZ/uhM4k=
+golang.org/x/crypto v0.17.0/go.mod h1:gCAAfMLgwOJRpTjQ2zCCt2OcSfYMTeZVSRtQlPC7Nq4=
+golang.org/x/net v0.10.0 h1:X2//UzNDwYmtCLn7To6G58Wr6f5ahEAQgKNzv9Y951M=
+golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
+golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20220704084225-05e143d24a9e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.8.0 h1:EBmGv8NaZBZTWvrbjNoL6HVt+IVy3QDQpJs7VRIw3tU=
+golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.15.0 h1:h48lPFYpsTvQJZF4EKyI4aLHaev3CxivZmv7yZig9pc=
+golang.org/x/sys v0.15.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/text v0.9.0 h1:2sjJmO8cDvYveuX97RDLsxlyUxLl+GHoLxBiRdHllBE=
+golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
+golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
+golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
+google.golang.org/protobuf v1.30.0 h1:kPPoIgf3TsEvrm0PFe15JQ+570QVxYzEvvHqChK+cng=
+google.golang.org/protobuf v1.30.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+rsc.io/pdf v0.1.1/go.mod h1:n8OzWcQ6Sp37PL01nO98y4iUCRdTGarVfzxY20ICaU4=

internal/dal/dal.go

@@ -0,0 +1,60 @@
+package dal
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+	"log"
+	"os"
+
+	"git.rosemyrtle.work/personal-finance/server/internal/entities"
+
+	_ "github.com/jackc/pgx/v5/stdlib"
+)
+
+type Connection struct {
+	db *sql.DB
+}
+
+func Open(credentials *entities.Credentials) (*Connection, error) {
+	if credentials == nil {
+		return nil, errors.New("missing credentials")
+	}
+
+	db, err := sql.Open("pgx", credentials.Database)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Unable to connect to database: %v\n", err)
+		return nil, err
+	}
+
+	if err := db.Ping(); err != nil {
+		log.Fatal(err)
+	}
+
+	return &Connection{db}, nil
+}
+
+func (c *Connection) Close() {
+	c.db.Close()
+}
+
+func (conn *Connection) Transactions() []entities.Transaction {
+	q := "SELECT t.date, t.description, t.amount FROM transactions t;"
+
+	rows, err := conn.db.Query(q)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	var result []entities.Transaction
+
+	for rows.Next() {
+		var t entities.Transaction
+		if err := rows.Scan(&t.Date, &t.Description, &t.Value); err != nil {
+			log.Fatal(err)
+		}
+		result = append(result, t)
+	}
+
+	return result
+}

internal/dal/dal_test.go

@@ -0,0 +1,43 @@
+package dal
+
+import (
+	"database/sql/driver"
+	"testing"
+	"time"
+
+	"github.com/DATA-DOG/go-sqlmock"
+)
+
+type AnyTime struct{}
+
+func (t AnyTime) Match(v driver.Value) bool {
+	_, ok := v.(time.Time)
+	return ok
+}
+
+// type AnyDecimal struct{}
+
+func TestTransactions(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	if err != nil {
+		t.Fatalf("failed to create a mock DB: %s", err)
+	}
+	defer db.Close()
+
+	conn := Connection{db}
+
+	rows := sqlmock.NewRows([]string{"date", "description", "amount"}).
+		AddRow(time.Now(), "income", 1000).
+		AddRow(time.Now(), "expense", -500)
+
+	mock.ExpectQuery("SELECT t.date, t.description, t.amount").WithoutArgs().WillReturnRows(rows)
+
+	transactions := conn.Transactions()
+	if len(transactions) <= 0 {
+		t.Error("No transactions returned")
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("unfulfilled expectations: %s", err)
+	}
+}

internal/entities/credentials.go

@@ -0,0 +1,5 @@
+package entities
+
+type Credentials struct {
+	Database string
+}

internal/entities/entities.go

@@ -0,0 +1,15 @@
+package entities
+
+import (
+	"time"
+
+	"github.com/shopspring/decimal"
+)
+
+type Transaction struct {
+	Id          int64
+	Date        time.Time
+	Description string
+	Value       decimal.Decimal
+	Category    string
+}