private async Task PopulateSourceDefinitionAsync()

in src/Core/Services/MetadataProviders/SqlMetadataProvider.cs [1267:1346]
63 lines of code
14 McCabe index (conditional complexity)

        private async Task PopulateSourceDefinitionAsync(
            string entityName,
            string schemaName,
            string tableName,
            SourceDefinition sourceDefinition,
            string[]? runtimeConfigKeyFields)
        {
            DataTable dataTable = await GetTableWithSchemaFromDataSetAsync(entityName, schemaName, tableName);

            List<DataColumn> primaryKeys = new(dataTable.PrimaryKey);
            if (runtimeConfigKeyFields is null || runtimeConfigKeyFields.Length == 0)
            {
                sourceDefinition.PrimaryKey = new(primaryKeys.Select(primaryKey => primaryKey.ColumnName));
            }
            else
            {
                sourceDefinition.PrimaryKey = new(runtimeConfigKeyFields);
            }

            if (sourceDefinition.PrimaryKey.Count == 0)
            {
                throw new DataApiBuilderException(
                       message: $"Primary key not configured on the given database object {tableName}",
                       statusCode: HttpStatusCode.ServiceUnavailable,
                       subStatusCode: DataApiBuilderException.SubStatusCodes.ErrorInInitialization);
            }

            _entities.TryGetValue(entityName, out Entity? entity);
            if (GetDatabaseType() is DatabaseType.MSSQL && entity is not null && entity.Source.Type is EntitySourceType.Table)
            {
                await PopulateTriggerMetadataForTable(entityName, schemaName, tableName, sourceDefinition);
            }

            using DataTableReader reader = new(dataTable);
            DataTable schemaTable = reader.GetSchemaTable();
            RuntimeConfig runtimeConfig = _runtimeConfigProvider.GetConfig();
            foreach (DataRow columnInfoFromAdapter in schemaTable.Rows)
            {
                string columnName = columnInfoFromAdapter["ColumnName"].ToString()!;

                if (runtimeConfig.IsGraphQLEnabled
                    && entity is not null
                    && IsGraphQLReservedName(entity, columnName, graphQLEnabledGlobally: runtimeConfig.IsGraphQLEnabled))
                {
                    throw new DataApiBuilderException(
                       message: $"The column '{columnName}' violates GraphQL name restrictions.",
                       statusCode: HttpStatusCode.ServiceUnavailable,
                       subStatusCode: DataApiBuilderException.SubStatusCodes.ErrorInInitialization);
                }

                ColumnDefinition column = new()
                {
                    IsNullable = (bool)columnInfoFromAdapter["AllowDBNull"],
                    IsAutoGenerated = (bool)columnInfoFromAdapter["IsAutoIncrement"],
                    SystemType = (Type)columnInfoFromAdapter["DataType"],
                    // An auto-increment column is also considered as a read-only column. For other types of read-only columns,
                    // the flag is populated later via PopulateColumnDefinitionsWithReadOnlyFlag() method.
                    IsReadOnly = (bool)columnInfoFromAdapter["IsAutoIncrement"]
                };

                // Tests may try to add the same column simultaneously
                // hence we use TryAdd here.
                // If the addition fails, it is assumed the column definition
                // has already been added and need not error out.
                sourceDefinition.Columns.TryAdd(columnName, column);
            }

            DataTable columnsInTable = await GetColumnsAsync(schemaName, tableName);

            PopulateColumnDefinitionWithHasDefaultAndDbType(
                sourceDefinition,
                columnsInTable);

            if (entity is not null && entity.Source.Type is EntitySourceType.Table)
            {
                // For MySql, database name is equivalent to schema name.
                string schemaOrDatabaseName = GetDatabaseType() is DatabaseType.MySQL ? GetDatabaseName() : schemaName;
                await PopulateColumnDefinitionsWithReadOnlyFlag(tableName, schemaOrDatabaseName, sourceDefinition);
            }
        }